Volkswagen Cars 2000-05

Accessory Drive Belts 1

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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.  

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.  

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.  

 
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