GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Accessory Drive Belts

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INSPECTION



Check the drive belt(s) every 15,000 miles/12 months (heavy usage) or 30,000 miles/24 months (light usage) for evidence of wear such as cracking, fraying and incorrect tension. Determine the belt tension at a point halfway between the pulleys by pressing on the belt with moderate thumb pressure. The belt should deflect about 1 / 4 in. (6mm) over a 7-10 in. (178-254mm) span, or 1 / 2 in. (12.7mm) over a 13-16 in. (330-406mm) span. If the deflection is found to be too much or too little, refer to the tension adjustments.

ADJUSTING TENSION



When adjusting belt tension note the following:

  1. A used belt is one that has been rotated at least one complete revolution on the pulleys. This begins the belt seating process and it must never be tensioned to the new belt specifications again.
  2.  
  3. It is better to have belts too loose than too tight, because overly tight belts will lead to bearing failure, particularly in the water pump and alternator. However, loose belts can also cause problems, as they place an extremely high impact load on the driven components due to the whipping action of the belt.
  4.  
  5. A GM Belt Tension Gauge No. BT-33-95-ACBN (regular V-belts), BT-33-97M (poly V-belts) or an equivalent tool is required for tensioning accessory drive belts on most 1982-86 trucks.
  6.  

V-Belt Tensioning (1983-86)

See Figures 1 and 2

  1. If the belt is cold, operate the engine (at idle speed) for 15 minutes; the belt will seat itself in the pulleys allowing the belt fibers to relax or stretch. If the belt is hot, allow it to cool, until it is warm to the touch.
  2.  
  3. Loosen the component-to-mounting bracket and pivot bolts.
  4.  
  5. Place GM Belt Tension Gauge No. BT-33-95-ACBN (standard V-belts), BT-33-97M (poly V-belts) or equivalent at the center of the belt between the longest span.
  6.  
  7. Pivot the component in order to apply more/less belt tension, as needed. Adjust the drive belt tension to the correct specifications.
  8.  
  9. While holding the component in a position resulting in the correct tension, tighten the component-to-mounting bracket and pivot bolts.
  10.  
  11. Double check that tension was not lost during tightening, then remove the tension gauge.
  12.  



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Fig. Fig. 1: A wooden tool handle or length of plastic pipe can be used to pivot the alternator outward while adjusting belt tension



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Fig. Fig. 2: A prybar can be used on some brackets (a power steering pump bracket in this case) to pivot the assembly outward

Serpentine Belt Tensioning (1987-93)

Most 1987-93 trucks are equipped with a single serpentine drive belt and an automatic tensioner. No belt adjustment is necessary as the tensioner adjusts by spring action. If a problem with the belt is suspected (it squeals often during operation or appears too loose), check the belt length scale on the tensioner. If outside the acceptable range, check for improper belt routing, belt damage or wear. Most multiple ribbed belts stretch very little. If you are still unsure, compare the belt to a new one at your local parts store. If the belt length is the same, the tensioner may need to be replaced.

On multiple ribbed serpentine drive belts, cracks across the rib material are a normal part of belt aging process. These cracks do not affect belt operation and do not indicate a need to replace it.

REMOVAL & INSTALLATION



V-Belt

See Figures 3, 4, 5, 6 and 7

  1. Loosen the component-to-mounting bracket and pivot bolts.
  2.  
  3. Rotate the component to relieve the tension on the drive belt.
  4.  
  5. Slip the drive belt from the component pulley and remove it from the engine.
  6.  

If the engine uses more than one belt, it may be necessary to remove other belts that are in front of the one being removed.

To install:
  1. Slip the belt into position over the pulleys.
  2.  
  3. Pivot the component to properly adjust the belt tension, then secure the mounting and pivot bolts. For details, please refer to the tension adjustment procedure earlier in this section.
  4.  



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Fig. Fig. 3: V-belt routing - 1.9L engine



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Fig. Fig. 4: V-belt routing - 2.0L engine



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Fig. Fig. 5: V-belt routing - 2.2L diesel engine



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Fig. Fig. 6: V-belt routing - 2.5L engine



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Fig. Fig. 7: V-belt routing - 2.8L engine

Serpentine Belt

See Figures 8 and 9

  1. Place a large box wrench or 1 / 2 in. breaker bar and socket over the tensioner pulley axis bolt, then rotate the tensioner counterclockwise loosen the belt.
  2.  
  3. While holding the tensioner in this position, remove the accessory drive belt and gently release the tensioner.
  4.  

Never allow the tensioner to snap back into position with or without the belt installed. Allowing the sudden release of tension could result in damage to the tensioner assembly.

To install:
  1. Begin to position the belt over the pulleys making sure the routing is correct.
  2.  
  3. Use the box wrench or breaker bar to pivot and hold the tensioner, then slip the belt fully into position.
  4.  
  5. Slowly ease the tensioner into contact with the belt.
  6.  
  7. No belt tensioning is necessary as the automatic tensioner is spring loaded.
  8.  



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Fig. Fig. 8: Serpentine belt routing - 2.5L and 2.8L engines



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Fig. Fig. 9: Serpentine belt routing - 4.3L engine

 
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