Volkswagen Golf/Jetta/Cabriole 1990-1999

Belts

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INSPECTION





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Fig. Some tensioners may be of the gear type such as the one shown here



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Fig. Simply turn the gear type with a wrench to adjust



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Fig. Once the belt is loosened, slide it off the pulleys to remove it

As drive belts wear, they tend to stretch, or lengthen. As a belt stretches over time, the tension decreases, which causes the belt to slip on the pulleys. This slippage not only causes operating problems (erratic steering, high engine temperatures, and charging system problems), but can greatly accelerate wear and damage to the belts themselves. Excessive slippage can cause a drive belt to glaze, overheat, and eventually break. Regular inspection and adjustment of the accessory drive belts will prolong their life, and ensure proper operation of belt-driven components.

To thoroughly inspect accessory drive belts, it's advisable to remove the lower engine cover, and view the condition of the belts through the right front wheel housing. If necessary, raise and safely support the vehicle to allow access. Viewing the belts from the engine compartment is sometimes possible, but belt-driven components such as the power steering pump and air conditioner compressor are often out of view from the engine compartment.

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 always best to replace all drive belts at one time, as a preventive maintenance measure, during this service operation.

Checking tension and adjustment





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Fig. Adjust tension by loosening both the pivot bolt and the upper adjustment bolt

To check belt tension on V-belts, push in on the drive belt about midway between the crankshaft pulley and the driven component. If the belt is less than 39.4 in. (1m) long, it should deflect between 0.80-0.120 in. (2-5mm). For longer belts, it should deflect between 0.40-0.060 in. (10-15mm). Belt size is usually printed on the back side of the belt. If it can't be read, it's probably time to replace it.

To compensate for the natural stretching of the accessory drive belts, a means of adjustment is necessary to change the distance between the crankshaft pulley and the driven component. Volkswagen employs several methods to accomplish this task. The first, which is most common on late-model vehicles, is with the use of an automatic belt tensioner. Most engines with poly-ribbed belts, or serpentine belts, are fitted with automatic belt tensioners. These tensioners can be either arm-type or rotary type. The second method (most common with V-belts) involves the driven component being rotated on a pivot. A slotted bracket and or arm(s) are used to hold the component in place once the belt tension is set. Within this method, there are four variations. The most basic variation is a simple slotted bracket with a bolt. This requires pulling or pushing on the driven component to achieve the desired belt tension. Some diesel and Mono-motronic engines use a spring-loaded alternator bracket that sets the belt tension after the slotted bolt is loosened. Other models use a rack and pinion design on the slotted adjustment bracket. This allows for effortless belt adjustment, since the pinion gear can be turned with a wrench to make adjustments. The final variation of the slotted style adjustment design uses a long adjuster bolt that pushes or pulls the driven component once the slotted bolt is loosened.

Poly-Ribbed Belts

Most all Volkswagen engines equipped with poly-ribbed belts are equipped with automatic adjusters, and do not require adjustment. The spring action of the tensioner compensates for the stretching of the belt. However, on some 1.8L Mono-motronic (ACC) and 1.9L diesel (AAZ, AHU) engines, A "semi-automatic" belt tensioning system is employed. This procedure is for belt adjustment of these engines only.

  1. Disconnect the negative battery cable.
  2.  
  3. Loosen the alternator pivot bolt, but do not remove it from the bracket.
  4.  
  5. Loosen, but do not remove the lower alternator bolt.
  6.  
  7. Push down on the alternator, and let it spring back up several times. If it does not spring freely, it may be necessary to further loosen the mounting bolts.
  8.  
  9. Reconnect the negative battery cable.
  10.  
  11. Start the engine, and allow it to idle for around 15 seconds.
  12.  
  13. Without leaning on the alternator, or touching the belt, tighten the alternator mounting bolts to 18 ft. lbs. (25 Nm).
  14.  


NOTE
When adjusting the driven components to set the drive belt tension, make absolutely sure all of the slotted bracket bolts are loosened before attempting to move the driven component. Attempting to rotate the pinion gear or push bolt without the slotted bolts loosened can cause damage to the fasteners, and in some cases, the component itself.

V-belts
Plain Slotted Brackets


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Fig. Alternator mounting with slotted brackets

  1. As a safety precaution, disconnect the negative battery cable.
  2.  
  3. Loosen the adjustment nut/bolt in the slotted bracket. Slightly loosen the pivot bolt.
  4.  
  5. Pull (don't pry) the component outward to increase tension. Push inward to reduce tension. Tighten the adjusting nut/bolt and the pivot bolt.
  6.  
  7. Recheck the drive belt tension, readjust if necessary.
  8.  
  9. Reconnect the negative battery cable.
  10.  

Slotted Brackets With adjustment Bolt


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Fig. Some components, like this air conditioner compressor, use a slotted bracket with an adjustment bolt. To adjust the tension, loosen the slotted bracket bolt . . .



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Fig. . . . and turn the adjustment bolt as necessary to achieve the proper belt tension

  1. As a safety precaution, disconnect the negative battery cable.
  2.  
  3. Loosen the slotted bracket bolt(s), and slightly loosen the pivot bolt(s).
  4.  
  5. If equipped, loosen the locknut(s) on the adjustment bolt(s).
  6.  
  7. Turn the threaded adjustment bolt(s) as necessary to achieve the correct tension.
  8.  
  9. Tighten the pivot bolt(s) and the slotted bracket bolt(s) securely.
  10.  
  11. While holding adjustment bolt(s) in position, tighten the lock nut(s) if equipped.
  12.  
  13. Recheck the drive belt tension and readjust if necessary.
  14.  
  15. Reconnect the negative battery cable.
  16.  

Rack And Pinion-type Slotted brackets


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Fig. Loosen the tension bolt (shown) and the alternator pivot bolt until the alternator swings freely under its own weight



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Fig. Adjust the V-belt by turning the nut on the tension bolt

  1. As a safety precaution, disconnect the negative battery cable.
  2.  
  3. Loosen the alternator pivot bolt, and the slotted bracket bolt, and the bracket mounting bolt.
  4.  
  5. Adjust the V-belt by turning the large nut (the pinion) nut while checking the belt deflection.
  6.  
  7. While holding the pinion nut steady, tighten the slotted bracket bolt to hold the adjustment setting.
  8.  
  9. Tighten the alternator pivot bolt, and the slotted bracket mounting bolt.
  10.  
  11. Recheck the drive belt tension and readjust if necessary.
  12.  
  13. Reconnect the negative battery cable.
  14.  

Split Pulley (Fox only)


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Fig. Belt adjusting shims on Fox models. Extra shims are stored behind the tensioner plate

On Fox models, the air conditioner compressor drive belts are adjusted by varying the number of discs (shims) between the halves of the crankshaft pulley.

  1. Remove the nuts/bolts securing the tensioner plate and crankshaft pulley halves.
  2.  
  3. Add or remove the amount of spacer discs between the pulley halves until the belt tension is correct.
  4.  


NOTE
If there are any shims left over, do not throw them away. Store the extra shims in front of the split pulley (behind the tensioner plate).

  1. Secure the pulley halves. Torque the pulley nuts or bolts to 15 ft. lbs. (20 Nm).
  2.  

REMOVAL & INSTALLATION





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Fig. On VR6 engines, an M8 bolt can be temporarily installed in the belt tensioning mechanism to relieve belt tension



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Fig. When removing ribbed belts, it's a good idea to mark the direction of the belt if it is to be reused



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Fig. Ribbed style serpentine belt

If a belt must be replaced, the driven component must be loosened and moved to its extreme loosest position (usually by moving it toward the center of the motor). On models with automatic belt adjusters, refer to the illustrations for information on relieving belt tension. After removing the old belt, check the pulleys for dirt or built-up material which could affect belt contact. Carefully install the new belt, 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, the width of the belt, the depth of the belt and the angle or profile of the V shape (always match up old belt with new belt if possible). The belt shape should exactly match the shape of the pulley; belts that are not an exact match can cause noise, slippage and premature failure.

After the new belt is installed, adjust it for proper tension. This is sometimes a three or four-handed job; you may find an assistant helpful. Make sure that all the bolts you loosened are retightened and that any other loosened belts have the correct tension. A new belt can be expected to stretch a bit after installation so be prepared to re-adjust your new belt.


NOTE
After installing a new belt, run the engine for about 5 minutes and then recheck the belt tension.

 
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