# Routine Maintenance and Tune-up

## Introduction

Proper maintenance and tune-up is the key to long and trouble-free vehicle life, and the work can yield its own rewards. Studies have shown that a properly tuned and maintained vehicle can achieve better gas mileage than an out-of-tune vehicle. As a conscientious owner and driver, set aside a Saturday morning, say once a month, to check or replace items which could cause major problems later. Keep your own personal log to jot down which services you performed, how much the parts cost you, the date, and the exact odometer reading at the time. Keep all receipts for such items as engine oil and filters, so that they may be referred to in case of related problems or to determine operating expenses. As a do-it-yourselfer, these receipts are the only proof you have that the required maintenance was performed. In the event of a warranty problem, these receipts will be invaluable.

The literature provided with your vehicle when it was originally delivered includes the factory recommended maintenance schedule. If you no longer have this literature, replacement copies are usually available from the dealer. A maintenance schedule is provided later in this section, in case you do not have the factory literature.

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## Air Cleaner (Element)

### REMOVAL & INSTALLATION

#### Except 1997-98 Super Duty and All Diesel

Detach the outlet tube clamp and ...

... carefully pull the tube and lid from the air cleaner housing

Remove the air cleaner element from the air cleaner housing

Inspect the condition of the air cleaner element and replace as necessary

1. Disconnect the negative battery cable.
2. Remove the outlet tube clamp from around the air cleaner element housing and remove the tube from the air cleaner housing. Position the tube out of the way.
3. Remove the air cleaner element from the air cleaner housing.

To install:

4. Installation is the reverse of removal.

#### 1997-98 Super Duty

Typical air cleaner assembly for 1997-98 F-250HD, F-350 and F-Super Duty models

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1. Disconnect the negative battery cable.
2. Remove the outlet tube clamps from the air cleaner housing and remove the tubes from the housing and secure out of the way.
3. Remove the screws securing the air cleaner cover and remove the cover.
4. Remove the air cleaner element from the air cleaner housing.

To install:

5. Installation is the reverse of removal.

#### 7.3L Diesel Engine

the air cleaner assembly—7.3L diesel engine

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The 7.3L engine is equipped with a air restriction gauge also referred to as a "filter minder". This device alerts the operator, or person performing the maintenance, of the condition of the filter element. When the "filter minder" reaches the YELLOW band in the gauge, it is time to replace the filter. The gauge can be reset by pushing the button on the end of the gauge.

1. Disconnect the negative battery cable.
2. Remove the air cleaner outlet tube-to-radiator support retaining screw.
3. Remove the air cleaner outlet tube clamps and remove the outlet duct.
4. Loosen the clamp retaining the engine air cleaner-to-air cleaner outlet tube adapter.
5. Loosen the nuts retaining the upper air cleaner housing to the lower air cleaner housing and remove the upper housing.
6. Remove the air cleaner element from the housing.

To install:

7. Before installing a new element, inspect the following:
   1. The housing gasket surfaces must be clean and undamaged.
   2. The water drain tube should be free of obstructions.
   3. The housing should be free of dents, ruptures and holes.

WARNING
A special filtering element is used on the 7.3L diesel engine. Use only a specific Ford filter element for replacement. Use of other elements can result in serious engine damage. Do not attempt to clean the element, replace it only.

8. The balance of the installation is the reverse of removal.

## Fuel Filter

### REMOVAL & INSTALLATION

The fuel filter is typically located along the frame rail

Remove the safety retaining clip from the fuel lines

Spread the special release tool open and ...

... place the tool on the filter inlet/outlet tube and carefully press the tool inward to release the garter spring on the spring lock coupling and ...

... remove the fuel line from the filter

Remove the filter from the clamp by pulling it straight out, but be careful, as you can see fuel will most likely spill out of the filter

The fuel filter is located along the frame rail under the vehicle and is accessible only from underneath the vehicle.

CAUTION
Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well ventilated area. Do not allow fuel spray or vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.

1. Disconnect the negative battery cable.
2. Properly relieve the fuel system pressure.
3. Raise and safely support the vehicle securely on jackstands.
4. Remove the fitting safety clips by gently prying them off. Usually they are held to the fuel lines by small retaining straps, however take care not to lose them.
5. Insert fuel line disconnect tool T90T-9550-S into the quick-connect fittings on the fuel lines.
6. Push the tool into the spring lock coupling and release the garter spring and separate the fitting.

Twisting the line sometimes aid in releasing stubborn connections.

CAUTION
Fuel will most likely run out of the line after it is removed from the filter.

7. Repeat the procedure for the other fuel line.
8. Grasp the fuel filter and carefully pull it straight out of the retaining clamp.

To install:

9. Push the filter into the retaining clamp aligning the front lip on the filter into the groove.
10. Attach the fuel lines to the filter until an audible click is heard from the connection. Sometimes the click is very quiet, so test the fitting by gently pulling on the line to see if it comes loose.
11. Attach the fitting safety clips by snapping them into place over the fittings.
12. Lower the vehicle
13. Connect the negative battery cable.
14. Start the vehicle and check the filter and lines for leaks.

## Fuel/Water Separator

### DRAINING

The 7.3L diesel engine is equipped with a fuel/water separator in the fuel supply line. A "Water in Fuel" indicator light is provided on the instrument panel to alert the driver. The light should glow when the ignition switch is in the start position to indicate proper light and water sensor function. If the light glows continuously while the engine is running, the water must be drained from the separator as soon as possible to prevent damage to the fuel injection system.

1. Shut off the engine. Failure to shut the engine OFF before draining the separator will cause air to enter the system.
2. Place an appropriate container under the drain valve on the water separator.
3. Manually open the drain valve, and allow the valve to remain open for approximately 15 seconds, or until clear water-free diesel fuel flows out.
4. After the water is completely drained, close the water drain valve.
5. Start the engine and check the "Water in Fuel" indicator light; it should not be lit. If it is lit and continues to stay so, there is a problem somewhere else in the fuel system.

### REMOVAL & INSTALLATION

Disconnect the fuel supply and return lines from the separator assembly

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Disconnect the two cylinder head fuel supply lines from the separator assembly

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Disconnect the electrical connector from the fuel filter/water separator

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Remove the fuel filter/water separator retaining bolts

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1. Disconnect both battery ground cables.
2. Open the fuel filter/water separator drain valve to release the fuel pressure. Completely drain the fuel filter/water separator assembly.
3. Disconnect the fuel supply and fuel return lines.
4. Disconnect the two cylinder head fuel supply lines.
5. Disconnect the electrical connector from the fuel filter/water separator.
6. Remove the fuel filter/water separator from the vehicle.
7. Disconnect the exhaust back pressure sensor electrical connector.
8. Remove the fuel filter/water separator retaining bolts.

WARNING
Clean all the fuel residue from the engine compartment. Failure to do so can cause personal injury or damage to the vehicle.

To install:

9. Installation is the reverse of removal.

## PCV Valve

### REMOVAL & INSTALLATION

PCV valve location—7.5L EFI engine

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PCV valve location— 5.8L EFI engines

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The PCV valve is located in the passenger side valve cover—4.6L engine; 4.2L, 5.4L and 6.8L similar

Grasp the valve and gently remove it from the grommet in the valve cover

Remove the valve from the hose by carefully twisting it out

1. Disconnect the oil separator hose from the PCV valve.
2. Remove the PCV valve from the grommet in the crankcase.
3. Inspect the grommet for deterioration.

To install:

4. If necessary, replace the crankcase grommet.
5. Install the PCV valve.
6. Install the hose.

## Evaporative Canister

### SERVICING

The fuel evaporative emission control canister should be inspected for damage or leaks at the hose fittings every 24,000 miles. Repair or replace any old or cracked hoses. Replace the canister if it is damaged in any way. The canister is located in the engine compartment on all F250HD/SD, F350, and all Super Duty trucks. . The canister is located on the rear crossmember on all F150, F250, Expedition and Navigator models.

For more detailed canister service, see Section 4.

## Battery

### PRECAUTIONS

Always use caution when working on or near the battery. Never allow a tool to bridge the gap between the negative and positive battery terminals. Also, be careful not to allow a tool to provide a ground between the positive cable/terminal and any metal component on the vehicle. Either of these conditions will cause a short circuit, leading to sparks and possible personal injury.

Do not smoke, have an open flame or create sparks near a battery; the gases contained in the battery are very explosive and, if ignited, could cause severe injury or death.

All batteries, regardless of type, should be carefully secured by a battery hold-down device. If this is not done, the battery terminals or casing may crack from stress applied to the battery during vehicle operation. A battery which is not secured may allow acid to leak out, making it discharge faster; such leaking corrosive acid can also eat away at components under the hood.

Always visually inspect the battery case for cracks, leakage and corrosion. A white corrosive substance on the battery case or on nearby components would indicate a leaking or cracked battery. If the battery is cracked, it should be replaced immediately.

### GENERAL MAINTENANCE

A battery that is not sealed must be checked periodically for electrolyte level. You cannot add water to a sealed maintenance-free battery (though not all maintenance-free batteries are sealed); however, a sealed battery must also be checked for proper electrolyte level, as indicated by the color of the built-in hydrometer "eye."

A typical location for the built-in hydrometer on maintenance-free batteries

Always keep the battery cables and terminals free of corrosion. Check these components about once a year. Refer to the removal, installation and cleaning procedures outlined in this section.

Keep the top of the battery clean, as a film of dirt can help completely discharge a battery that is not used for long periods. A solution of baking soda and water may be used for cleaning, but be careful to flush this off with clear water. DO NOT let any of the solution into the filler holes. Baking soda neutralizes battery acid and will de-activate a battery cell.

Batteries in vehicles which are not operated on a regular basis can fall victim to parasitic loads (small current drains which are constantly drawing current from the battery). Normal parasitic loads may drain a battery on a vehicle that is in storage and not used for 6-8 weeks. Vehicles that have additional accessories such as a cellular phone, an alarm system or other devices that increase parasitic load may discharge a battery sooner. If the vehicle is to be stored for 6-8 weeks in a secure area and the alarm system, if present, is not necessary, the negative battery cable should be disconnected at the onset of storage to protect the battery charge.

Remember that constantly discharging and recharging will shorten battery life. Take care not to allow a battery to be needlessly discharged.

### BATTERY FLUID

Check the battery electrolyte level at least once a month, or more often in hot weather or during periods of extended vehicle operation. On non-sealed batteries, the level can be checked either through the case on translucent batteries or by removing the cell caps on opaque-cased types. The electrolyte level in each cell should be kept filled to the split ring inside each cell, or the line marked on the outside of the case.

If the level is low, add only distilled water through the opening until the level is correct. Each cell is separate from the others, so each must be checked and filled individually. Distilled water should be used, because the chemicals and minerals found in most drinking water are harmful to the battery and could significantly shorten its life.

If water is added in freezing weather, the vehicle should be driven several miles to allow the water to mix with the electrolyte. Otherwise, the battery could freeze.

Although some maintenance-free batteries have removable cell caps for access to the electrolyte, the electrolyte condition and level on all sealed maintenance-free batteries must be checked using the built-in hydrometer "eye." The exact type of eye varies between battery manufacturers, but most apply a sticker to the battery itself explaining the possible readings. When in doubt, refer to the battery manufacturer's instructions to interpret battery condition using the built-in hydrometer.

Although the readings from built-in hydrometers found in sealed batteries may vary, a green eye usually indicates a properly charged battery with sufficient fluid level. A dark eye is normally an indicator of a battery with sufficient fluid, but one which may be low in charge. And a light or yellow eye is usually an indication that electrolyte supply has dropped below the necessary level for battery (and hydrometer) operation. In this last case, sealed batteries with an insufficient electrolyte level must usually be discarded.

#### Checking the Specific Gravity

A hydrometer is required to check the specific gravity on all batteries that are not maintenance-free. On batteries that are maintenance-free, the specific gravity is checked by observing the built-in hydrometer "eye" on the top of the battery case. Check with your battery's manufacturer for proper interpretation of its built-in hydrometer readings.

On non-maintenance-free batteries, the fluid level can be checked through the case on translucent models; the cell caps must be removed on other models

If the fluid level is low, add only distilled water through the opening until the level is correct

Check the specific gravity of the battery's electrolyte with a hydrometer

CAUTION
Battery electrolyte contains sulfuric acid. If you should splash any on your skin or in your eyes, flush the affected area with plenty of clear water. If it lands in your eyes, get medical help immediately.

The fluid (sulfuric acid solution) contained in the battery cells will tell you many things about the condition of the battery. Because the cell plates must be kept submerged below the fluid level in order to operate, maintaining the fluid level is extremely important. And, because the specific gravity of the acid is an indication of electrical charge, testing the fluid can be an aid in determining if the battery must be replaced. A battery in a vehicle with a properly operating charging system should require little maintenance, but careful, periodic inspection should reveal problems before they leave you stranded.

As stated earlier, the specific gravity of a battery's electrolyte level can be used as an indication of battery charge. At least once a year, check the specific gravity of the battery. It should be between 1.20 and 1.26 on the gravity scale. Most auto supply stores carry a variety of inexpensive battery testing hydrometers. These can be used on any non-sealed battery to test the specific gravity in each cell.

The battery testing hydrometer has a squeeze bulb at one end and a nozzle at the other. Battery electrolyte is sucked into the hydrometer until the float is lifted from its seat. The specific gravity is then read by noting the position of the float. If gravity is low in one or more cells, the battery should be slowly charged and checked again to see if the gravity has come up. Generally, if after charging, the specific gravity between any two cells varies more than 50 points (0.50), the battery should be replaced, as it can no longer produce sufficient voltage to guarantee proper operation.

### CABLES

Once a year (or as necessary), the battery terminals and the cable clamps should be cleaned. Loosen the clamps and remove the cables, negative cable first. On batteries with posts on top, the use of a puller specially made for this purpose is recommended. These are inexpensive and available in most auto parts stores. Side terminal battery cables are secured with a small bolt.

Clean the cable clamps and the battery terminal with a wire brush, until all corrosion, grease, etc., is removed and the metal is shiny. It is especially important to clean the inside of the clamp thoroughly (an old knife is useful here), since a small deposit of foreign material or oxidation there will prevent a sound electrical connection and inhibit either starting or charging. Special tools are available for cleaning these parts, one type for conventional top post batteries and another type for side terminal batteries. It is also a good idea to apply some dielectric grease to the terminal, as this will aid in the prevention of corrosion.

After the clamps and terminals are clean, reinstall the cables, negative cable last; DO NOT hammer the clamps onto battery posts. Tighten the clamps securely, but do not distort them. Give the clamps and terminals a thin external coating of grease after installation, to retard corrosion.

Check the cables at the same time that the terminals are cleaned. If the cable insulation is cracked or broken, or if the ends are frayed, the cable should be replaced with a new cable of the same length and gauge.

Maintenance is performed with household items and with special tools like this post cleaner

The underside of this special battery tool has a wire brush to clean post terminals

Place the tool over the battery posts and twist to clean until the metal is shiny

A special tool is available to pull the clamp from the post

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The cable ends should be cleaned as well

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### CHARGING

CAUTION
The chemical reaction which takes place in all batteries generates explosive hydrogen gas. A spark can cause the battery to explode and splash acid. To avoid serious personal injury, be sure there is proper ventilation and take appropriate fire safety precautions when connecting, disconnecting, or charging a battery and when using jumper cables.

A battery should be charged at a slow rate to keep the plates inside from getting too hot. However, if some maintenance-free batteries are allowed to discharge until they are almost "dead," they may have to be charged at a high rate to bring them back to "life." Always follow the charger manufacturer's instructions on charging the battery.

### REPLACEMENT

When it becomes necessary to replace the battery, select one with an amperage rating equal to or greater than the battery originally installed. Deterioration and just plain aging of the battery cables, starter motor, and associated wires makes the battery's job harder in successive years. The slow increase in electrical resistance over time makes it prudent to install a new battery with a greater capacity than the old.

## Belts

### INSPECTION

Inspect the belts for signs of glazing or cracking. A glazed belt will be perfectly smooth from slippage, while a good belt will have a slight texture of fabric visible. Cracks will usually start at the inner edge of the belt and run outward. All worn or damaged drive belts should be replaced immediately. It is best to replace all drive belts at one time, as a preventive maintenance measure, during this service operation.

There are typically 3 types of accessory drive belts found on vehicles today

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An example of a healthy drive belt

Deep cracks in this belt will cause flex, building up heat that will eventually lead to belt failure

The cover of this belt is worn, exposing the critical reinforcing cords to excessive wear

Installing too wide a belt can result in serious belt wear and/or breakage

### ADJUSTMENT

All engines use an automatic drive belt tensioner. On the 7.5L engine, there are two belts, one uses the automatic tensioner, while the alternator belt requires periodic tensioning. On all belts using an automatic tensioner, no adjustment is necessary because the tensioner adjusts for belt wear. To adjust the tension on the 7.5L engine alternator belt, loosen the adjusting bolts and rotate the alternator until the proper tension is on the drive belt and tighten the adjusting bolts. It is recommended that the belt tension indicator mark be inspected with the engine OFF at 60,000 mile (96,000 km) intervals. If the wear indicator mark is out of specification, the drive belt is worn or an incorrect drive belt has been installed.

### REMOVAL & INSTALLATION

The drive belt routing can be found on a label under the hood or in the engine compartment. If the label is missing, there are diagrams of all the engines covered in this manual. However, be sure to verify the belt routing on your engine matches one of these before removing the belt. If the routing does not match one of our diagrams, the belt could possibly be routed wrong. A good idea is to draw your own diagram of the belt routing prior to removing the old belt from the engine.

Accessory serpentine belt routing—5.8L engine

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Accessory serpentine belt routing—7.5L engine

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Accessory serpentine belt routing—7.3L turbo diesel engine

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Accessory serpentine belt routing—7.5L F-super duty motorhome engine

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Accessory serpentine belt routing—4.6L, 5.4L, and 6.8L engines with A/C

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Accessory serpentine belt routing—4.6L, 5.4L, and 6.8L engines without A/C

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Accessory serpentine belt routing—4.2L engine with A/C

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Accessory serpentine belt routing—4.2L engine without A/C

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Usually a label is affixed in the engine compartment with the proper belt routing on it

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The tensioner on the 4.6L engine requires a 3/8 inch drive tool to rotate the tensioner

Rotate the tensioner and remove the drive belt from around one of the pulleys

#### Except 7.5L Engine Alternator Belt

1. Disconnect the negative battery cable.

The proper belt routing is included in this section, however, it is a good idea to make a simple drawing of the belt routing of your engine for installation reference before removing the belt.

2. Rotate the drive belt tensioner to relieve the belt tension. The procedure is as follows:
   1. On the 4.6L, 5.4L and 6.8L engines, use a 1/2 drive tool or a special belt removal tool to rotate the tensioner in the proper direction as directed by the rotation arrow on the tensioner.
   2. On the 4.2L, 5.8L, 7.5L and 7.3L engines, use a 16mm socket and drive tool or a special belt removal tool to rotate the tensioner in the proper direction as directed by the rotation arrow on the tensioner.
   3. While holding the tensioner back, remove the belt from around one pulley.
3. Remove the belt from around the remaining pulleys.

To install:

4. Position the belt around the pulleys in the proper routing with the exception of one pulley. It is easiest to keep the belt off of the easiest pulley to access. Hold the belt tight with your hands and using the proper tool for your engine, rotate the tensioner in the correct direction and place the belt around the final pulley.
5. Release the tensioner slowly until it sits firmly against the belt.

If the tensioner does not touch the belt or the wear indicator marks are not within specification, the belt is routed incorrectly or the wrong belt has been installed.

6. Connect the negative battery cable.

#### 7.5L Engine Alternator Belt

1. Disconnect the negative battery cable.
2. Loosen the adjusting bolts on the alternator.
3. Carefully rotate the alternator to relieve the tension on the drive belt.
4. Remove the drive belt from around the pulleys and remove.

To install:

5. Properly route the drive belt around the pulleys.
6. Rotate the alternator until the proper tension is achieved and tighten the adjusting bolts.
7. Connect the negative battery cable.

## Hoses

### INSPECTION

Upper and lower radiator hoses, along with the heater hoses, should be checked for deterioration, leaks and loose hose clamps at least every 15,000 miles (24,000 km). It is also wise to check the hoses periodically in early spring and at the beginning of the fall or winter when you are performing other maintenance. A quick visual inspection could discover a weakened hose which might have left you stranded if it had remained unrepaired.

Whenever you are checking the hoses, make sure the engine and cooling system are cold. Visually inspect for cracking, rotting or collapsed hoses, and replace as necessary. Run your hand along the length of the hose. If a weak or swollen spot is noted when squeezing the hose wall, the hose should be replaced.

The cracks developing along this hose are a result of age-related hardening

A hose clamp that is too tight can cause older hoses to separate and tear on either side of the clamp

A soft spongy hose (identifiable by the swollen section) will eventually burst and should be replaced

Hoses are likely to deteriorate from the inside if the cooling system is not periodically flushed

### REMOVAL & INSTALLATION

1. Remove the radiator pressure cap.

CAUTION
Never remove the pressure cap while the engine is running, or personal injury from scalding hot coolant or steam may result. If possible, wait until the engine has cooled to remove the pressure cap. If this is not possible, wrap a thick cloth around the pressure cap and turn it slowly to the stop. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, use the cloth to turn and remove the cap.

2. Position a clean container under the radiator and/or engine draincock or plug, then open the drain and allow the cooling system to drain to an appropriate level. For some upper hoses, only a little coolant must be drained. To remove hoses positioned lower on the engine, such as a lower radiator hose, the entire cooling system must be emptied.

CAUTION
When draining coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant may be reused unless it is contaminated or several years old.

3. Loosen the hose clamps at each end of the hose requiring replacement. Clamps are usually either of the spring tension type (which require pliers to squeeze the tabs and loosen) or of the screw tension type (which require screw or hex drivers to loosen). Pull the clamps back on the hose away from the connection.
4. Twist, pull and slide the hose off the fitting, taking care not to damage the neck of the component from which the hose is being removed.

If the hose is stuck at the connection, do not try to insert a screwdriver or other sharp tool under the hose end in an effort to free it, as the connection and/or hose may become damaged. Heater connections especially may be easily damaged by such a procedure. If the hose is to be replaced, use a single-edged razor blade to make a slice along the portion of the hose which is stuck on the connection, perpendicular to the end of the hose. Do not cut deep so as to prevent damaging the connection. The hose can then be peeled from the connection and discarded.

5. Clean both hose mounting connections. Inspect the condition of the hose clamps and replace them, if necessary.

To install:

6. Dip the ends of the new hose into clean engine coolant to ease installation.
7. Slide the clamps over the replacement hose, then slide the hose ends over the connections into position.
8. Position and secure the clamps at least 1/4 in. (6.35mm) from the ends of the hose. Make sure they are located beyond the raised bead of the connector.
9. Close the radiator or engine drains and properly refill the cooling system with the clean drained engine coolant or a suitable mixture of ethylene glycol coolant and water.
10. If available, install a pressure tester and check for leaks. If a pressure tester is not available, run the engine until normal operating temperature is reached (allowing the system to naturally pressurize), then check for leaks.

CAUTION
If you are checking for leaks with the system at normal operating temperature, BE EXTREMELY CAREFUL not to touch any moving or hot engine parts. Once temperature has been reached, shut the engine OFF, and check for leaks around the hose fittings and connections which were removed earlier.

## CV-Boots

### INSPECTION

The CV (Constant Velocity) boots should be checked for damage each time the oil is changed and any other time the vehicle is raised for service. These boots keep water, grime, dirt and other damaging matter from entering the CV-joints. Any of these could cause early CV-joint failure which can be expensive to repair. Heavy grease thrown around the inside of the front wheel(s) and on the brake caliper/drum can be an indication of a torn boot. Thoroughly check the boots for missing clamps and tears. If the boot is damaged, it should be replaced immediately. Please refer to Section 7 for procedures.

CV-boots must be inspected periodically for damage

A torn boot should be replaced immediately

## Spark Plugs

A typical spark plug consists of a metal shell surrounding a ceramic insulator. A metal electrode extends downward through the center of the insulator and protrudes a small distance. Located at the end of the plug and attached to the side of the outer metal shell is the side electrode. The side electrode bends in at a 90° angle so that its tip is just past and parallel to the tip of the center electrode. The distance between these two electrodes (measured in thousandths of an inch or hundredths of a millimeter) is called the spark plug gap.

The spark plug does not produce a spark, but instead provides a gap across which the current can arc. The coil produces anywhere from 20,000 to 50,000 volts (depending on the type and application) which travels through the wires to the spark plugs. The current passes along the center electrode and jumps the gap to the side electrode, and in doing so, ignites the air/fuel mixture in the combustion chamber.

Cross-section of a spark plug

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### SPARK PLUG HEAT RANGE

Spark plug heat range is the ability of the plug to dissipate heat. The longer the insulator (or the farther it extends into the engine), the hotter the plug will operate; the shorter the insulator (the closer the electrode is to the block's cooling passages) the cooler it will operate. A plug that absorbs little heat and remains too cool will quickly accumulate deposits of oil and carbon since it is not hot enough to burn them off. This leads to plug fouling and consequently to misfiring. A plug that absorbs too much heat will have no deposits but, due to the excessive heat, the electrodes will burn away quickly and might possibly lead to preignition or other ignition problems. Preignition takes place when plug tips get so hot that they glow sufficiently to ignite the air/fuel mixture before the actual spark occurs. This early ignition will usually cause a pinging during low speeds and heavy loads.

Spark plug heat range

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The general rule of thumb for choosing the correct heat range when picking a spark plug is: if most of your driving is long distance, high speed travel, use a colder plug; if most of your driving is stop and go, use a hotter plug. Original equipment plugs are generally a good compromise between the 2 styles and most people never have the need to change their plugs from the factory-recommended heat range.

### REMOVAL & INSTALLATION

Grasp the plug wire and carefully twist the wire to release the retainer from the spark plug

If the plug wire is stubborn, a pair of special removal pliers is recommended to remove the wires from the plugs

Carefully remove the plug wire from the cylinder head

A special spark plug socket with a rubber insert is needed to remove the spark plugs. Typically the spark plugs on engines covered by this manual require a 5/8 socket

Using a suitable drive tool and the special socket, loosen the spark plug and ...

... remove the spark plug from the engine

Clean out the spark plug bore and threads before installing the new spark plug

An inspection of the old spark plugs will give a general idea of the condition of the motor, compare the spark plugs to the chart in this section

A piece of fuel line or a small hose is useful in installing the spark plugs to avoid stripping the threads

A set of spark plugs usually requires replacement after about 20,000-30,000 miles (32,000-48,000 km), depending on your style of driving. In normal operation plug gap increases about 0.001 in. (0.025mm) for every 2500 miles (4000 km). As the gap increases, the plug's voltage requirement also increases. It requires a greater voltage to jump the wider gap and about two to three times as much voltage to fire the plug at high speeds than at idle. The improved air/fuel ratio control of modern fuel injection combined with the higher voltage output of modern ignition systems will often allow an engine to run significantly longer on a set of standard spark plugs, but keep in mind that efficiency will drop as the gap widens (along with fuel economy and power).

When you're removing spark plugs, work on one at a time. Don't start by removing the plug wires all at once, because, unless you number them, they may become mixed up. Take a minute before you begin and number the wires with tape.

1. Disconnect the negative battery cable, and if the vehicle has been run recently, allow the engine to thoroughly cool.
2. Except on the 5.4L and 6.8L engines, carefully twist the spark plug wire boot to loosen it, then pull upward and remove the boot from the spark plug. Be sure to pull on the boot and not on the wire, otherwise the connector located inside the boot may become separated.
3. On the 5.4L and 6.8L engines, unplug the electrical connector on the individual cylinder ignition coil and remove the retaining screw. Remove the coil from the cylinder head, taking care in removing it from the spark plug.
4. Using compressed air, blow any water or debris from the spark plug well to assure that no harmful contaminants are allowed to enter the combustion chamber when the spark plug is removed. If compressed air is not available, use a rag or a brush to clean the area.

Remove the spark plugs when the engine is cold, if possible, to prevent damage to the threads. If removal of the plugs is difficult, apply a few drops of penetrating oil or silicone spray to the area around the base of the plug, and allow it a few minutes to work.

5. Using a spark plug socket that is equipped with a rubber insert to properly hold the plug, turn the spark plug counterclockwise to loosen and remove the spark plug from the bore.

WARNING
Be sure not to use a flexible extension on the socket. Use of a flexible extension may allow a shear force to be applied to the plug. A shear force could break the plug off in the cylinder head, leading to costly and frustrating repairs.

To install:

6. Inspect the spark plug boot for tears or damage. If a damaged boot is found, the spark plug wire must be replaced.
7. Using a wire feeler gauge, check and adjust the spark plug gap. When using a gauge, the proper size should pass between the electrodes with a slight drag. The next larger size should not be able to pass while the next smaller size should pass freely.
8. Carefully thread the plug into the bore by hand. If resistance is felt before the plug is almost completely threaded, back the plug out and begin threading again. In small, hard to reach areas, an old spark plug wire and boot could be used as a threading tool. The boot will hold the plug while you twist the end of the wire and the wire is supple enough to twist before it would allow the plug to crossthread.

WARNING
Do not use the spark plug socket to thread the plugs. Always carefully thread the plug by hand or using an old plug wire to prevent the possibility of crossthreading and damaging the cylinder head bore.

9. Carefully tighten the spark plug. If the plug you are installing is equipped with a crush washer, seat the plug, then tighten about 1/4 turn to crush the washer. If you are installing a tapered seat plug, tighten the plug to specifications provided by the vehicle or plug manufacturer.
10. Except for the 5.4L and 6.8L engines, apply a small amount of silicone dielectric compound to the end of the spark plug lead or inside the spark plug boot to prevent sticking, then install the boot to the spark plug and push until it clicks into place. The click may be felt or heard, then gently pull back on the boot to assure proper contact.
11. On the 5.4L and 6.8L engines, slide the coil into the cylinder head and engage the coil onto the spark plug. Tighten the retaining screw and attach the electrical connector.
12. Connect the negative battery cable.

### INSPECTION & GAPPING

Check the plugs for deposits and wear. If they are not going to be replaced, clean the plugs thoroughly. Remember that any kind of deposit will decrease the efficiency of the plug. Plugs can be cleaned on a spark plug cleaning machine, which can sometimes be found in service stations, or you can do an acceptable job of cleaning with a stiff brush. If the plugs are cleaned, the electrodes must be filed flat. Use an ignition points file, not an emery board or the like, which will leave deposits. The electrodes must be filed perfectly flat with sharp edges; rounded edges reduce the spark plug voltage by as much as 50%.

Check spark plug gap before installation. The ground electrode (the L-shaped one connected to the body of the plug) must be parallel to the center electrode and the specified size wire gauge (please refer to the Tune-Up Specifications chart for details) must pass between the electrodes with a slight drag.

NEVER adjust the gap on a used platinum type spark plug.

Always check the gap on new plugs as they are not always set correctly at the factory. Do not use a flat feeler gauge when measuring the gap on a used plug, because the reading may be inaccurate. A round-wire type gapping tool is the best way to check the gap. The correct gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller and one larger. The smaller gauge should go through easily, while the larger one shouldn't go through at all. Wire gapping tools usually have a bending tool attached. Use that to adjust the side electrode until the proper distance is obtained. Absolutely never attempt to bend the center electrode. Also, be careful not to bend the side electrode too far or too often as it may weaken and break off within the engine, requiring removal of the cylinder head to retrieve it.

Inspect the spark plug to determine engine running conditions

Click to enlarge

A variety of tools and gauges are needed for spark plug service

Checking the spark plug gap with a feeler gauge

Adjusting the spark plug gap

If the standard plug is in good condition, the electrode may be filed flat—WARNING: do not file platinum plugs

## Spark Plug Wires

### TESTING

Checking plug wire resistance through the distributor cap with an ohmmeter

Click to enlarge

Checking individual plug wire resistance with a digital ohmmeter

The 5.4L, 6.8L and 7.3L engines do not utilize spark plug wires. The 5.4L and 6.8L engines use a direct ignition or "coil over plug" type ignition in which each individual cylinder has it's own coil attached to a boot that fits on the spark plug. The 7.3L engine is a diesel, and as anyone familiar with diesels is aware, diesel engines do not utilize an ignition system, instead rely on high compression ratios and the extreme cylinder temperatures, as well as a glow plug system used on cold starts to fire the fuel/air mixture.

At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring.

Every 50,000 miles (80,000 km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

To check resistance, an ohmmeter should be used on each wire to test resistance between the end connectors. Remove and install/replace the wires in order, one-by-one.

Resistance on these wires should be 4,000-6,000 ohms per foot. To properly measure this, remove the wires from the plugs and the coil pack. Do not pierce any ignition wire for any reason. Measure only from the two ends. Take the length and multiply it by 6,000 to achieve the maximum resistance allowable in each wire, resistance should not exceed this value. If resistance does exceed this value, replace the wire.

Whenever the high tension wires are removed from the plugs, coil, or distributor, silicone grease must be applied to the boot before reconnection. Coat the entire interior surface with Ford silicone grease D7AZ-19A331-A or its equivalent.

### REMOVAL & INSTALLATION

Grasp the plug wire and carefully twist the wire to release the retainer from the spark plug

If the plug wire is stubborn, a pair of special removal pliers is recommended to remove the wires from the plugs

Carefully remove the plug wire from the cylinder head

Remove the plug wires from the ignition coil by squeezing the retaining tabs and carefully lifting the wires up

Disconnect the plug wire retaining clips from the wires and ...

... remove the plug wires from the engine

The 5.4L, 6.8L and 7.3L engines do not utilize spark plug wires. The 5.4L and 6.8L engines use a direct ignition or "coil over plug" type ignition in which each individual cylinder has it's own coil attached to a boot that fits on the spark plug. The 7.3L engine is a diesel, and as anyone familiar with diesels is aware, diesel engines do not utilize an ignition system, instead rely on high compression ratios and the extreme cylinder temperatures, as well as a glow plug system used on cold starts to fire the fuel/air mixture.

1. Label each spark plug wire and make a note of its routing.

Don't rely on wiring diagrams or sketches for spark plug wire routing. Improper arrangement of spark plug wires will induce voltage between wires, causing misfiring and surging. Be careful to arrange spark plug wires properly.

2. Starting with the longest wire, disconnect the spark plug wire from the spark plug and then from the coil pack or the distributor cap.
3. Disconnect the ignition wire from the coil pack, if equipped, by squeezing the locking tabs and twisting while pulling upward.
4. Disconnect the ignition wire from the distributor cap, if equipped, by gently twisting and pulling upward on the wire.

To install:

5. If replacing the spark plug wires, match the old wire with an appropriately sized wire in the new set.
6. Lubricate the boots and terminals with dielectric grease and install the wire on the coil pack or distributor cap. Make sure the wire snaps into place.
7. Route the wire in the exact path as the original and connect the wire to the spark plug.
8. Repeat the process for each remaining wire, working from the longest wire to the shortest.

## Distributor Cap and Rotor

### REMOVAL & INSTALLATION

The distributor cap is held to the distributor by retaining clips

Click to enlarge

The rotor has a locating boss which must be aligned on the distributor

Click to enlarge

1. Disconnect the negative battery cable.
2. Label and disconnect the spark plug wires from the distributor cap.

Depending on the reason for removing the distributor cap, it may make more sense to leave the spark plug wires attached. This is handy if you are testing spark plug wires, or if removal is necessary to access other components, and wire length allows you to reposition the cap out of the way.

3. Detach the two spring clips that secure the cap to the distributor.
4. Remove the cap from the distributor.

The rotor is press fit onto the distributor shaft.

5. Pull the rotor straight up to remove.

To install:

6. Inspect the cap and rotor as described below.
7. Align the rotor locating boss on the distributor shaft and install by pressing into place.
8. Align the distributor cap on the distributor and secure the spring clips.
9. Connect the spark plug wires to their proper terminals.
10. Connect the negative battery cable.

### INSPECTION

After removing the distributor cap and rotor, clean the components (both inside and outside of the cap) using soap and water. If compressed air is available, carefully dry the components (wearing safety goggles) or allow the parts to air dry. You can dry them with a clean, soft cloth, but don't leave any lint or moisture behind.

Once the cap and rotor have been thoroughly cleaned, check for cracks, carbon tracks, burns or other physical damage. Make sure the distributor cap's center button is free of damage. Check the cap terminals for dirt or corrosion. Always check the rotor blade and spring closely for damage. Replace any components where damage is found.

Inspection points for the distributor cap

Click to enlarge

Inspection points for the distributor rotor

Click to enlarge

## Ignition Timing

### GENERAL INFORMATION

Periodic adjustment of the ignition timing is not necessary for any engine covered by this manual. If ignition timing is not within specification, there is a fault in the engine control system. Diagnose and repair the problem as necessary.

Ignition timing is the measurement, in degrees of crankshaft rotation, of the point at which the spark plugs fire in each of the cylinders. It is measured in degrees before or after Top Dead Center (TDC) of the compression stroke.

Ideally, the air/fuel mixture in the cylinder will be ignited by the spark plug just as the piston passes TDC of the compression stroke. If this happens, the piston will be at the beginning of the power stroke just as the compressed and ignited air/fuel mixture forces the piston down and turns the crankshaft. Because it takes a fraction of a second for the spark plug to ignite the mixture in the cylinder, the spark plug must fire a little before the piston reaches TDC. Otherwise, the mixture will not be completely ignited as the piston passes TDC and the full power of the explosion will not be used by the engine.

The timing measurement is given in degrees of crankshaft rotation before the piston reaches TDC (BTDC). If the setting for the ignition timing is 10 BTDC, each spark plug must fire 10 degrees before each piston reaches TDC. This only holds true, however, when the engine is at idle speed. The combustion process must be complete by 23° ATDC to maintain proper engine performance, fuel mileage, and low emissions.

As the engine speed increases, the pistons go faster. The spark plugs have to ignite the fuel even sooner if it is to be completely ignited when the piston reaches TDC. On all engines covered in this manual, spark timing changes are accomplished electronically by the Powertrain Control Module (PCM), based on input from engine sensors.

If the ignition is set too far advanced (BTDC), the ignition and expansion of the fuel in the cylinder will occur too soon and tend to force the piston down while it is still traveling up. This causes pre ignition or "knocking and pinging". If the ignition spark is set too far retarded, or after TDC (ATDC), the piston will have already started on its way down when the fuel is ignited. The piston will be forced down for only a portion of its travel, resulting in poor engine performance and lack of power.

Timing marks or scales can be found on the rim of the crankshaft pulley and the timing cover. The marks on the pulley correspond to the position of the piston in the No. 1 cylinder. A stroboscopic (dynamic) timing light is hooked onto the No. 1 cylinder spark plug wire. Every time the spark plug fires, the timing light flashes. By aiming the light at the timing marks while the engine is running, the exact position of the piston within the cylinder can be easily read (the flash of light makes the mark on the pulley appear to be standing still). Proper timing is indicated when the mark and scale are in specified alignment.

WARNING
When checking timing with the engine running, take care not to get the timing light wires tangled in the fan blades and/or drive belts.

### INSPECTION

1. Place the vehicle in P or N with the parking brake applied and the drive wheels blocked.
2. Connect a suitable tachometer and timing light to the engine, as per the manufacturer's instructions.
3. Remove the SPOUT (Spark Output) connector.
4. Start the engine and allow it reach normal operating temperature. Make sure all accessories are off.
5. Check that the idle speed is within the specified rpm range.
6. Following the timing light manufacturer's instructions, aim the timing light and check the ignition timing. As the light flashes, note the position of the mark on the crankshaft pulley against the scale on the timing cover. Timing should be 8-12 degrees BTDC.
7. If the ignition timing is not within specification, refer to ADJUSTMENT, in this Section.
8. Install the SPOUT connector.
9. Stop the engine and remove the tachometer and timing light.

### ADJUSTMENT

#### 5.8L and 7.5L Engines

If the ignition timing is not within specification, loosen the distributor hold-down bolt and carefully rotate the distributor in the correct direction to achieve the desired advance/retard required to correct the timing. Recheck the timing as you rotate the distributor and when the desired timing is reached, tighten the hold-down bolt.

#### Except For 5.8L, 6.8L And 7.3L Engines

If the ignition timing is not within specification, there is a fault in the engine control system. Diagnose and repair the problem as necessary.

## Valve Lash

### ADJUSTMENT

The only engines requiring a valve lash adjustment are the 5.8L and 7.5L engines. All other engines are contain hydraulic self-adjusting lifters or other devices.

#### 5.8L Engine

Mark the damper on the 5.8L engine

Click to enlarge

Click to enlarge

1. Rotate the crankshaft by hand so that No. 1 piston is at TDC of the compression stroke. Make a chalk mark on the damper at that point, then, make 2 more chalk marks about 90° apart in a clockwise direction.
2. With No. 1 at TDC, slowly apply pressure, using Lifter Bleed-down wrench T70P-6513-A, or equivalent, to completely bottom the lifter, on the following valves:

- No. 1 intake and exhaust
- No. 4 intake
- No. 3 exhaust
- No. 8 intake
- No. 7 exhaust

Take care to avoid excessive pressure that might bend the pushrod. Hold the lifter in this position and check the clearance between the rocker arm and the valve stem tip. Allowable clearance is 2.5-5.0mm (0.098-0.198 in.) with a desired clearance of 3.1-4.4mm (0.123-0.173 in.).

3. If the clearance is less than specified, install a shorter pushrod. If the clearance is greater than specified, install a longer pushrod.
4. Rotate the crankshaft clockwise—viewed from the front—180°, until the next chalk mark is aligned with the timing pointer. Repeat the procedure for:

- No. 3 intake
- No. 2 exhaust
- No. 7 intake
- No. 6 exhaust

5. Rotate the crankshaft to the next chalk mark—90°—and repeat the procedure for:

- No. 2 intake
- No. 4 exhaust
- No. 5 intake and exhaust
- No. 6 intake
- No. 8 exhaust

### 7.5L ENGINE

1. Rotate the crankshaft by hand so that No. 1 piston is at TDC of the compression stroke. Make a chalk mark on the damper at that point.
2. With No. 1 at TDC, slowly apply pressure, using Lifter Bleed-down wrench T70P-6513-A, or equivalent, to completely bottom the lifter, on the following valves:

- No. 1 intake and exhaust
- No. 3 intake
- No. 4 exhaust
- No. 7 intake
- No. 5 exhaust
- No. 8 intake and exhaust

Take care to avoid excessive pressure that might bend the pushrod. Hold the lifter in this position and check the clearance between the rocker arm and the valve stem tip. Allowable clearance is 1.9-4.4mm (0.075-0.175 in.) with a desired clearance of 2.5-3.8mm (0.100-0.150 in.).

3. If the clearance is less than specified, install a shorter pushrod. If the clearance is greater than specified, install a longer pushrod.
4. Rotate the crankshaft clockwise—viewed from the front—360°, until the chalk mark is once again aligned with the timing pointer. Repeat the procedure for:

- No. 2 intake and exhaust
- No. 4 intake
- No. 3 exhaust
- No. 5 intake
- No. 7 exhaust
- No. 6 intake and exhaust

## Idle Speed and Mixture Adjustments

The engines covered by this manual utilize sophisticated fuel injection systems in which an engine control computer utilizes information from various sensors to control idle speed and air/fuel mixtures. No periodic adjustments are either necessary or possible on these systems. If a problem is suspected, please refer to Sections 4 of this manual for more information on electronic engine controls and fuel injection.

## Air Conditioning System

### SYSTEM SERVICE & REPAIR

It is recommended that the A/C system be serviced by an EPA 609 certified automotive technician utilizing a refrigerant recovery/recycling machine.

The do-it-yourselfer should not service his/her own vehicle's A/C system for many reasons, including legal concerns, personal injury, environmental damage and cost. The following are some of the reasons why you may decide not to service your own vehicle's A/C system.

According to the U.S. Clean Air Act, it is a federal crime to service or repair (involving the refrigerant) a Motor Vehicle Air Conditioning (MVAC) system for money without being EPA certified. It is also illegal to vent R-134a refrigerant into the atmosphere.

State and/or local laws may be more strict than the federal regulations, so be sure to check with your state and/or local authorities for further information. For further federal information on the legality of servicing your A/C system, call the EPA Stratospheric Ozone Hotline.

Federal law dictates that a fine of up to $25,000 may be levied on people convicted of venting refrigerant into the atmosphere. Additionally, the EPA may pay up to $10,000 for information or services leading to a criminal conviction of the violation of these laws.

When servicing an A/C system you run the risk of handling or coming in contact with refrigerant, which may result in skin or eye irritation or frostbite. Although low in toxicity (due to chemical stability), inhalation of concentrated refrigerant fumes is dangerous and can result in death; cases of fatal cardiac arrhythmia have been reported in people accidentally subjected to high levels of refrigerant. Some early symptoms include loss of concentration and drowsiness.

Also, refrigerants can decompose at high temperatures (near gas heaters or open flame), which may result in hydrofluoric acid, hydrochloric acid and phosgene (a fatal nerve gas).

R-134a refrigerant is a greenhouse gas which, if allowed to vent into the atmosphere, will contribute to global warming (the Greenhouse Effect).

It is usually more economically feasible to have a certified MVAC automotive technician perform A/C system service to your vehicle. While it is illegal to service an A/C system without the proper equipment, the home mechanic would have to purchase an expensive refrigerant recovery/recycling machine to service his/her own vehicle.

### PREVENTIVE MAINTENANCE

Although the A/C system should not be serviced by the do-it-yourselfer, preventive maintenance can be practiced and A/C system inspections can be performed to help maintain the efficiency of the vehicle's A/C system. For preventive maintenance, perform the following:

- The easiest and most important preventive maintenance for your A/C system is to be sure that it is used on a regular basis. Running the system for five minutes each month (no matter what the season) will help ensure that the seals and all internal components remain lubricated.

Some newer vehicles automatically operate the A/C system compressor whenever the windshield defroster is activated. When running, the compressor lubricates the A/C system components; therefore, the A/C system would not need to be operated each month.

- In order to prevent heater core freeze-up during A/C operation, it is necessary to maintain a proper antifreeze protection. Use a hand-held coolant tester (hydrometer) to periodically check the condition of the antifreeze in your engine's cooling system.

Antifreeze should not be used longer than the manufacturer specifies.

- For efficient operation of an air conditioned vehicle's cooling system, the radiator cap should have a holding pressure which meets manufacturer's specifications. A cap which fails to hold these pressures should be replaced.
- Any obstruction of or damage to the condenser configuration will restrict air flow which is essential to its efficient operation. It is, therefore, a good rule to keep this unit clean and in proper physical shape.

Bug screens which are mounted in front of the condenser (unless they are original equipment) are regarded as obstructions.

- The condensation drain tube expels any water, which accumulates on the bottom of the evaporator housing, into the engine compartment. If this tube is obstructed, the air conditioning performance can be restricted and condensation buildup can spill over onto the vehicle's floor.

### SYSTEM INSPECTION

Although the A/C system should not be serviced by the do-it-yourselfer, preventive maintenance can be practiced and A/C system inspections can be performed to help maintain the efficiency of the vehicle's A/C system. For A/C system inspection, perform the following:

The easiest and often most important check for the air conditioning system consists of a visual inspection of the system components. Visually inspect the air conditioning system for refrigerant leaks, damaged compressor clutch, abnormal compressor drive belt tension and/or condition, plugged evaporator drain tube, blocked condenser fins, disconnected or broken wires, blown fuses, corroded connections and poor insulation.

A refrigerant leak will usually appear as an oily residue at the leakage point in the system. The oily residue soon picks up dust or dirt particles from the surrounding air and appears greasy. Through time, this will build up and appear to be a heavy dirt impregnated grease.

For a thorough visual and operational inspection, check the following:

- Check the surface of the radiator and condenser for dirt, leaves or other material which might block air flow.
- Check for kinks in hoses and lines. Check the system for leaks.
- Make sure the drive belt is properly tensioned. When the air conditioning is operating, make sure the drive belt is free of noise or slippage.
- Make sure the blower motor operates at all appropriate positions, then check for distribution of the air from all outlets with the blower on HIGH or MAX.

Keep in mind that under conditions of high humidity, air discharged from the A/C vents may not feel as cold as expected, even if the system is working properly. This is because vaporized moisture in humid air retains heat more effectively than dry air, thereby making humid air more difficult to cool.

- Make sure the air passage selection lever is operating correctly. Start the engine and warm it to normal operating temperature, then make sure the temperature selection lever is operating correctly.

## Windshield Wipers

### ELEMENT (REFILL) CARE & REPLACEMENT

For maximum effectiveness and longest element life, the windshield and wiper blades should be kept clean. Dirt, tree sap, road tar and so on will cause streaking, smearing and blade deterioration if left on the glass. It is advisable to wash the windshield carefully with a commercial glass cleaner at least once a month. Wipe off the rubber blades with the wet rag afterwards. Do not attempt to move wipers across the windshield by hand; damage to the motor and drive mechanism will result.

To inspect and/or replace the wiper blade elements, place the wiper switch in the LOW speed position and the ignition switch in the ACC position. When the wiper blades are approximately vertical on the windshield, turn the ignition switch to OFF.

Examine the wiper blade elements. If they are found to be cracked, broken or torn, they should be replaced immediately. Replacement intervals will vary with usage, although ozone deterioration usually limits element life to about one year. If the wiper pattern is smeared or streaked, or if the blade chatters across the glass, the elements should be replaced. It is easiest and most sensible to replace the elements in pairs.

If your vehicle is equipped with aftermarket blades, there are several different types of refills and your vehicle might have any kind. Aftermarket blades and arms rarely use the exact same type blade or refill as the original equipment. Here are some typical aftermarket blades; not all may be available for your vehicle:

The Anco® type uses a release button that is pushed down to allow the refill to slide out of the yoke jaws. The new refill slides back into the frame and locks in place.

Some Trico® refills are removed by locating where the metal backing strip or the refill is wider. Insert a small screwdriver blade between the frame and metal backing strip. Press down to release the refill from the retaining tab.

Other types of Trico® refills have two metal tabs which are unlocked by squeezing them together. The rubber filler can then be withdrawn from the frame jaws. A new refill is installed by inserting the refill into the front frame jaws and sliding it rearward to engage the remaining frame jaws. There are usually four jaws; be certain when installing that the refill is engaged in all of them. At the end of its travel, the tabs will lock into place on the front jaws of the wiper blade frame.

Another type of refill is made from polycarbonate. The refill has a simple locking device at one end which flexes downward out of the groove into which the jaws of the holder fit, allowing easy release. By sliding the new refill through all the jaws and pushing through the slight resistance when it reaches the end of its travel, the refill will lock into position.

To replace the Tridon® refill, it is necessary to remove the wiper blade. This refill has a plastic backing strip with a notch about 1 in. (25mm) from the end. Hold the blade (frame) on a hard surface so that the frame is tightly bowed. Grip the tip of the backing strip and pull up while twisting counterclockwise. The backing strip will snap out of the retaining tab. Do this for the remaining tabs until the refill is free of the blade. The length of these refills is molded into the end and they should be replaced with identical types.

Regardless of the type of refill used, be sure to follow the part manufacturer's instructions closely. Make sure that all of the frame jaws are engaged as the refill is pushed into place and locked. If the metal blade holder and frame are allowed to touch the glass during wiper operation, the glass will be scratched.

Bosch® wiper blade and fit kit

Lexor® wiper blade and fit kit

Pylon® wiper blade and adapter

Trico® wiper blade and fit kit

Tripledge® wiper blade and fit kit

To remove and install a Lexor® wiper blade refill, slip out the old insert and slide in a new one

On Pylon® inserts, the clip at the end has to be removed prior to sliding the insert off

On Trico® wiper blades, the tab at the end of the blade must be turned up ...

... then the insert can be removed. After installing the replacement insert, bend the tab back

The Tripledge® wiper blade insert is removed and installed using a securing clip

## Tires and Wheels

Common sense and good driving habits will afford maximum tire life. Fast starts, sudden stops and hard cornering are hard on tires and will shorten their useful life span. Make sure that you don't overload the vehicle or run with incorrect pressure in the tires. Both of these practices will increase tread wear.

For optimum tire life, keep the tires properly inflated, rotate them often and have the wheel alignment checked periodically.

Inspect your tires frequently. Be especially careful to watch for bubbles in the tread or sidewall, deep cuts or underinflation. Replace any tires with bubbles in the sidewall. If cuts are so deep that they penetrate to the cords, discard the tire. Any cut in the sidewall of a radial tire renders it unsafe. Also look for uneven tread wear patterns that may indicate the front end is out of alignment or that the tires are out of balance.

### TIRE ROTATION

Tires must be rotated periodically to equalize wear patterns that vary with a tire's position on the vehicle. Tires will also wear in an uneven way as the front steering/suspension system wears to the point where the alignment should be reset.

Rotating the tires will ensure maximum life for the tires as a set, so you will not have to discard a tire early due to wear on only part of the tread. Regular rotation is required to equalize wear.

When rotating "unidirectional tires," make sure that they always roll in the same direction. This means that a tire used on the left side of the vehicle must not be switched to the right side and vice-versa. Such tires should only be rotated front-to-rear or rear-to-front, while always remaining on the same side of the vehicle. These tires are marked on the sidewall as to the direction of rotation; observe the marks when reinstalling the tire(s).

Common tire rotation patterns for 4 and 5-wheel rotations

Click to enlarge

Unidirectional tires are identifiable by sidewall arrows and/or the word "rotation"

Some styled or "mag" wheels may have different offsets front to rear. In these cases, the rear wheels must not be used up front and vice-versa. Furthermore, if these wheels are equipped with unidirectional tires, they cannot be rotated unless the tire is remounted for the proper direction of rotation.

The compact or space-saver spare is strictly for emergency use. It must never be included in the tire rotation or placed on the vehicle for everyday use.

### TIRE DESIGN

For maximum satisfaction, tires should be used in sets of four. Mixing of different types (radial, bias-belted, fiberglass belted) must be avoided. In most cases, the vehicle manufacturer has designated a type of tire on which the vehicle will perform best. Your first choice when replacing tires should be to use the same type of tire that the manufacturer recommends.

When radial tires are used, tire sizes and wheel diameters should be selected to maintain ground clearance and tire load capacity equivalent to the original specified tire. Radial tires should always be used in sets of four.

P-Metric tire coding

Click to enlarge

CAUTION
Radial tires should never be used on only the front axle.

When selecting tires, pay attention to the original size as marked on the tire. Most tires are described using an industry size code sometimes referred to as P-Metric. This allows the exact identification of the tire specifications, regardless of the manufacturer. If selecting a different tire size or brand, remember to check the installed tire for any sign of interference with the body or suspension while the vehicle is stopping, turning sharply or heavily loaded.

#### Snow Tires

Good radial tires can produce a big advantage in slippery weather, but in snow, a street radial tire does not have sufficient tread to provide traction and control. The small grooves of a street tire quickly pack with snow and the tire behaves like a billiard ball on a marble floor. The more open, chunky tread of a snow tire will self-clean as the tire turns, providing much better grip on snowy surfaces.

To satisfy municipalities requiring snow tires during weather emergencies, most snow tires carry either an M + S designation after the tire size stamped on the sidewall, or the designation "all-season." In general, no change in tire size is necessary when buying snow tires.

Most manufacturers strongly recommend the use of 4 snow tires on their vehicles for reasons of stability. If snow tires are fitted only to the drive wheels, the opposite end of the vehicle may become very unstable when braking or turning on slippery surfaces. This instability can lead to unpleasant endings if the driver can't counteract the slide in time.

Note that snow tires, whether 2 or 4, will affect vehicle handling in all non-snow situations. The stiffer, heavier snow tires will noticeably change the turning and braking characteristics of the vehicle. Once the snow tires are installed, you must re-learn the behavior of the vehicle and drive accordingly.

Consider buying extra wheels on which to mount the snow tires. Once done, the "snow wheels" can be installed and removed as needed. This eliminates the potential damage to tires or wheels from seasonal removal and installation. Even if your vehicle has styled wheels, see if inexpensive steel wheels are available. Although the look of the vehicle will change, the expensive wheels will be protected from salt, curb hits and pothole damage.

### TIRE STORAGE

If they are mounted on wheels, store the tires at proper inflation pressure. All tires should be kept in a cool, dry place. If they are stored in the garage or basement, do not let them stand on a concrete floor; set them on strips of wood, a mat or a large stack of newspaper. Keeping them away from direct moisture is of paramount importance. Tires should not be stored upright, but in a flat position.

### INFLATION & INSPECTION

The importance of proper tire inflation cannot be overemphasized. A tire employs air as part of its structure. It is designed around the supporting strength of the air at a specified pressure. For this reason, improper inflation drastically reduces the tire's ability to perform as intended. A tire will lose some air in day-to-day use; having to add a few pounds of air periodically is not necessarily a sign of a leaking tire.

Two items should be a permanent fixture in every glove compartment: an accurate tire pressure gauge and a tread depth gauge. Check the tire pressure (including the spare) regularly with a pocket type gauge. Too often, the gauge on the end of the air hose at your corner garage is not accurate because it suffers too much abuse. Always check tire pressure when the tires are cold, as pressure increases with temperature. If you must move the vehicle to check the tire inflation, do not drive more than a mile before checking. A cold tire is generally one that has not been driven for more than three hours.

Tires should be checked frequently for any sign of puncture or damage

Tires with deep cuts, or cuts which bulge, should be replaced immediately

Examples of inflation-related tire wear patterns

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Radial tires have a characteristic sidewall bulge; don't try to measure pressure by looking at the tire. Use a quality air pressure gauge

Common tire wear patterns and causes

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A plate or sticker is normally provided somewhere in the vehicle (door post, hood, tailgate or trunk lid) which shows the proper pressure for the tires. Never counteract excessive pressure build-up by bleeding off air pressure (letting some air out). This will cause the tire to run hotter and wear quicker.

CAUTION
Never exceed the maximum tire pressure embossed on the tire! This is the pressure to be used when the tire is at maximum loading, but it is rarely the correct pressure for everyday driving. Consult the owner's manual or the tire pressure sticker for the correct tire pressure.

Once you've maintained the correct tire pressures for several weeks, you'll be familiar with the vehicle's braking and handling personality. Slight adjustments in tire pressures can fine-tune these characteristics, but never change the cold pressure specification by more than 2 psi. A slightly softer tire pressure will give a softer ride but also yield lower fuel mileage. A slightly harder tire will give crisper dry road handling but can cause skidding on wet surfaces. Unless you're fully attuned to the vehicle, stick to the recommended inflation pressures.

All tires made since 1968 have built-in tread wear indicator bars that show up as 1/2 in. (13mm) wide smooth bands across the tire when 1/16 in. (1.5mm) of tread remains. The appearance of tread wear indicators means that the tires should be replaced. In fact, many states have laws prohibiting the use of tires with less than this amount of tread.

Tread wear indicators will appear when the tire is worn

Accurate tread depth indicators are inexpensive and handy

You can check your own tread depth with an inexpensive gauge or by using a Lincoln head penny. Slip the Lincoln penny (with Lincoln's head upside-down) into several tread grooves. If you can see the top of Lincoln's head in 2 adjacent grooves, the tire has less than 1/16 in. (1.5mm) tread left and should be replaced. You can measure snow tires in the same manner by using the "tails" side of the Lincoln penny. If you can see the top of the Lincoln memorial, it's time to replace the snow tire(s).

A penny works well for a quick check of tread depth

### CARE OF SPECIAL WHEELS

If you have invested money in magnesium, aluminum alloy or sport wheels, special precautions should be taken to make sure your investment is not wasted and that your special wheels look good for the life of the vehicle.

Special wheels are easily damaged and/or scratched. Occasionally check the rims for cracking, impact damage or air leaks. If any of these are found, replace the wheel. But in order to prevent this type of damage and the costly replacement of a special wheel, observe the following precautions:

- Use extra care not to damage the wheels during removal, installation, balancing, etc. After removal of the wheels from the vehicle, place them on a mat or other protective surface. If they are to be stored for any length of time, support them on strips of wood. Never store tires and wheels upright; the tread may develop flat spots.
- When driving, watch for hazards; it doesn't take much to crack a wheel.
- When washing, use a mild soap or non-abrasive dish detergent (keeping in mind that detergent tends to remove wax). Avoid cleansers with abrasives or the use of hard brushes. There are many cleaners and polishes for special wheels.
- If possible, remove the wheels during the winter. Salt and sand used for snow removal can severely damage the finish of a wheel.
- Make certain the recommended lug nut torque is never exceeded or the wheel may crack. Never use snow chains on special wheels; severe scratching will occur.