Liberty, Wrangler, 1997-2005

Accessory Drive Belts

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Adjustment



Periodic drive belt tensioning is not necessary, because an automatic spring-loaded tensioner is used with these belts to maintain proper adjustment at all times. The tensioner is also useful as a wear indicator. When the belt is properly installed, the arrow on the tensioner housing must point within the acceptable range lines on the tensioner's face. If the arrow falls outside the range, either an improper belt has been installed or the belt is worn beyond its useful life span. In either case, a new belt must be installed immediately to assure proper engine operation and to prevent possible accessory damage.

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Fig. Typical drive belt automatic tensioner wear indicator

Serpentine Belt
2.5L And 4.0L Engines With Power Steering

This type of drive belt is tensioned by a tensioner, which makes precise tension adjustment easy.

  1. Loosen the idelr and lockbolt which is in the center of the idler.
  2.  
  3. Turn the tensioner adjusting bolt or threaded coupling to increase or decrease the amount of tension on the drive belt, as necessary.
  4.  
  5. When the belt tension is correct, tighten the lockbolt.
  6.  


CAUTION
Disconnect the negative battery cable.

Tension is maintained using an automatic tensioner pulley assembly. The drive belt is tensioned by adjusting the position of the idler pulley, accomplished by moving the adjuster bolt on the idler mechanism.

Belt Tension Inspection



Although different maintenance intervals are given by each manufacturer, it is a good rule of thumb to inspect the drive belts every 15,000 miles (24,000 km) or 12 months (whichever occurs first). Determine the belt tension at a point half-way between the pulleys by pressing on the belt with moderate thumb pressure. The belt should deflect about 1 / 4 - 1 / 2 in. (6-13mm) at this point. Note that -deflection- is not play, but the ability of the belt, under actual tension, to stretch slightly and give.

Inspect the belts for the following signs of damage or wear: glazing, cracking, fraying, crumbling or missing chunks. 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. A belt that is fraying will have the fabric backing de-laminating its self from the belt. A belt that is crumbling or missing chunks will have voids in the cross-section of the belt, some times the section missing chunks will be in the pulley groove and not easily seen. 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.

Although it is generally easier on the component to have the belt too loose than too tight, a very loose belt may place a high impact load on a bearing due to the whipping or snapping action of the belt. A belt that is slightly loose may slip, especially when component loads are high. This slippage may be hard to identify. For example, the generator belt may run okay during the day, and then slip at night when headlights are turned on. Slipping belts wear quickly not only due to the direct effect of slippage but also because of the heat the slippage generates. Extreme slippage may even cause a belt to burn. A very smooth, glazed appearance on the belt's sides, as opposed to the obvious pattern of a fabric cover, indicates that the belt has been slipping.

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Fig. An example of a healthy drive belt



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



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



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

Although many manufacturers recommend that the drive belt(s) be inspected every 30,000 miles (48,000 km) or more, it is really a good idea to check them at least once a year, or at every major fluid change. Whichever interval you choose, the belts should be checked for wear or damage. Obviously, a damaged drive belt can cause problems should it give way while the vehicle is in operation. But, improper length belts (too short or long), as well as excessively worn belts, can also cause problems. Loose accessory drive belts can lead to poor engine cooling and diminished output from the alternator, air conditioning compressor or power steering pump. A belt that is too tight places a severe strain on the driven unit and can wear out bearings quickly.

Serpentine drive belts should be inspected for rib chunking (pieces of the ribs breaking off), severe glazing, frayed cords or other visible damage. Any belt which is missing sections of 2 or more adjacent ribs which are 1 / 2 inches. (13mm) or longer must be replaced. You might want to note that serpentine belts do tend to form small cracks across the backing. If the only wear you find is in the form of one or more cracks are across the backing and NOT parallel to the ribs, the belt is still good and does not need to be replaced.

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Fig. Typical wear patterns for a serpentine drive belt

Drive Belt Routings





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Fig. Often the underhood label will display the serpentine drive belt routing



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Fig. Accessory serpentine belt routing-Jeep 3.7L engine.



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Fig. Often the underhood label will display the serpentine drive belt routing



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Fig. Verifying serpentine belt alignment in the pulley



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Fig. Accessory serpentine belt routing-Jeep Wrangler 1999-02 2.5L and 4.0L engine without A/C

Removal & Installation



If a belt must be replaced, the driven unit or idler pulley must be loosened and moved to its extreme loosest position, generally by moving it toward the center of the motor. After removing the old belt, check the pulleys for dirt or built-up material which could affect belt contact. Carefully install the new belt, remembering that it is new and unused; it may appear to be just a little too small to fit over the pulley flanges. Fit the belt over the largest pulley (usually the crankshaft pulley at the bottom center of the motor) first, then work on the smaller one(s). Gentle pressure in the direction of rotation is helpful. Some belts run around a third, or idler pulley, which acts as an additional pivot in the belt's path. It may be possible to loosen the idler pulley as well as the main component, making your job much easier. Depending on which belt(s) you are changing, it may be necessary to loosen or remove other interfering belts to get at the one(s) you want.

When buying replacement belts, remember that the fit is critical according to the length of the belt (-diameter-), the width of the belt, the depth of the belt and the angle or profile of the V shape or the ribs. The belt shape should match the shape of the pulley exactly; belts that are not an exact match can cause noise, slippage and premature failure.

After the new belt is installed, draw tension on it by moving the driven unit or idler pulley away from the motor and tighten its mounting bolts. This is sometimes a three or four-handed job; you may find an assistant helpful. Make sure that all the bolts you loosened are tightened and that any other loosened belts also have the correct tension. A new belt can be expected to stretch a bit after installation so, be prepared to readjust your new belt, if needed, within the first two hundred miles of use.

2.4L Engine

NOTE
The belt routing schematics are published from the latest information available at the time of publication. If anything differs between these schematics and the Belt Routing Label, use the schematics on Belt Routing Label. This label is located in the engine compartment.


CAUTION
Do not let tensioner arm snap back to the free arm position, as severe damage may occur to the tensioner.


NOTE
Belt tension is not adjustable. Belt adjustment is maintained by an automatic (spring load) belt tensioner

  1. Disconnect negative battery cable from battery.
  2.  
  3. Rotate belt tensioner until it contacts its stop Remove belt, then slowly rotate the tensioner into the free-arm position
  4.  

To install:

  1. Check condition of all pulleys
    CAUTION
    When installing the serpentine accessory drive belt, the belt MUST be routed correctly. If not, the engine may overheat due to the water pump rotating in the wrong direction.

  2.  
  3. Install new belt or . Route the belt around all pulleys except the idler pulley. Rotate the tensioner arm until it contacts its stop position Route the belt around the idler and slowly let the tensioner rotate into the belt. Make sure the belt is seated onto all pulleys.
  4.  
  5. With the drive belt installed, inspect the belt wear indicator. On 2.4L Engines the gap between the tang and the housing stop (measurement A) must not exceed 24 mm (.94 inches).
  6.  


NOTE
The belt routing schematics are published from the latest information available at the time of publication. If anything differs between these schematics and the Belt Routing Label, use the schematics on Belt Routing Label. This label is located in the engine compartment.


CAUTION
Do not let tensioner arm snap back to the free arm position, as severe damage may occur to the tensioner.


NOTE
Belt tension is not adjustable. Belt adjustment is maintained by an automatic (spring load) belt tensioner

  1. Disconnect negative battery cable from battery.
  2.  
  3. Rotate belt tensioner until it contacts its stop Remove belt, then slowly rotate the tensioner into the free-arm position
  4.  

To install:

  1. Check condition of all pulleys
    CAUTION
    When installing the serpentine accessory drive belt, the belt MUST be routed correctly. If not, the engine may overheat due to the water pump rotating in the wrong direction.

  2.  
  3. Install new belt or . Route the belt around all pulleys except the idler pulley. Rotate the tensioner arm until it contacts its stop position Route the belt around the idler and slowly let the tensioner rotate into the belt. Make sure the belt is seated onto all pulleys.
  4.  
  5. With the drive belt installed, inspect the belt wear indicator. The gap between the tang and the housing stop (measurement A) must not exceed 24 mm (.94 inches).
  6.  

2.5L & 4.0L Engine

Because serpentine belts use a spring loaded tensioner for adjustment, belt replacement tends to be somewhat easier than it used to be on engines where accessories were pivoted and bolted in place for tension adjustment. Basically, all belt replacement involves is to pivot the tensioner to loosen the belt, then slide the belt off of the pulleys. The two most important points are to pay CLOSE attention to the proper belt routing (since serpentine belts tend to be -snaked'' all different ways through the pulleys) and to make sure the V-ribs are properly seated in all the pulleys.

Although belt routing diagrams have been included in this section, the first places you should check for proper belt routing are the labels in your engine compartment. These should include a belt routing diagram which may reflect changes made during a production run.

  1. Disconnect the negative battery cable for safety. This will help assure that no one mistakenly cranks the engine over with your hands between the pulleys, and that the cooling fan cannot activate while servicing the belt(s).
    NOTE
    Take a good look at the installed belt and make a note of the routing. Before removing the belt, make sure the routing matches that of the belt routing diagram. If for some reason a diagram does not match (you may not have the original engine or it may have been modified), carefully note the changes on a piece of paper.

  2.  
  3. For tensioners equipped with a 1 / 2 in. (13mm) square hole, insert the drive end of a large breaker bar into the hole. Use the breaker bar to pivot the tensioner away from the drive belt. For tensioners not equipped with this hole, use the proper-sized socket and breaker bar (or a large handled wrench) on the tensioner idler pulley center bolt to pivot the tensioner away from the belt. This will loosen the belt sufficiently that it can be pulled off of one or more of the pulleys. It is usually easiest to carefully pull the belt out from underneath the tensioner pulley itself.
  4.  
  5. Once the belt is off one of the pulleys, gently pivot the tensioner back into position. DO NOT allow the tensioner to snap back, as this could damage the tensioner's internal parts.
  6.  
  7. Now finish removing the belt from the other pulleys and remove it from the engine.
  8.  

To install:

  1. While referring to the proper routing diagram (which you identified earlier), begin to route the belt over the pulleys, leaving whichever pulley you first released it from for last.
  2.  
  3. Once the belt is mostly in place, carefully pivot the tensioner and position the belt over the final pulley. As you begin to allow the tensioner back into contact with the belt, run your hand around the pulleys and make sure the belt is properly seated in the ribs. If not, release the tension and seat the belt.
  4.  
  5. Once the belt is installed, take another look at all the pulleys to double check your installation.
  6.  
  7. Connect the negative battery cable, then start and run the engine to check belt operation.
  8.  
  9. Once the engine has reached normal operating temperature, turn the ignition OFF and check that the belt tensioner arrow is within the proper adjustment range.
  10.  

2.8L Diesel
  1. Disconnect negative battery cable.
  2.  
  3. Rotate belt tensioner until it contacts its stop. Remove belt, then slowly rotate the tensioner into the free arm position.
  4.  

To install:

  1. Check condition of all pulleys.
    CAUTION
    When installing the serpentine accessory drive belt, the belt MUST be routed correctly. If not, the engine may overheat due to the water pump rotating in the wrong direction.

  2.  
  3. Install new belt. Route the belt around all pulleys except the idler pulley . Rotate the tensioner arm until it contacts its stop position. Route the belt around the idler and slowly let the tensioner rotate into the belt. Make sure the belt is seated onto all pulleys.
  4.  

3.7L Engine
  1. Disconnect negative battery cable from battery.
  2.  
  3. Rotate belt tensioner until it contacts its stop. Remove belt, then slowly rotate the tensioner into the free arm position.
  4.  

To install:

  1. Check condition of all pulleys.
    CAUTION
    When installing the serpentine accessory drive belt, the belt MUST be routed correctly. If not, the engine may overheat due to the water pump rotating in the wrong direction .

  2.  
  3. Install new belt . Route the belt around all pulleys except the idler pulley. Rotate the tensioner arm until it contacts its stop position. Route the belt around the idler and slowly let the tensioner rotate into the belt. Make sure the belt is seated onto all pulleys.
  4.  
  5. With the drive belt installed, inspect the belt wear indicator . On 3.7L Engines the gap between the tang and the housing stop ( measurement A ) must not exceed 24 mm (.94 inches).
  6.  

Pivoting Type

CAUTION
On vehicles with an electric cooling fan, disable the power to the fan by disengaging the fan motor wiring connector or removing the negative battery cable before replacing or adjusting the drive belts. Otherwise, the fan may engage even though the ignition is OFF .

 
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