Jeep CJ/Scrambler 1971-1986 Repair Guide

Belts

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See Figures 1, 2, 3, 4, 5 and 6

Once a year or at 12,000 mile intervals, the tension (and condition) of the alternator, power steering (if so equipped), air conditioning (if so equipped), and Thermactor air pump drive belts should be checked, and, if necessary, adjusted. Loose accessory drive belts can lead to poor engine cooling and diminish alternator, power steering pump, air conditioning compressor or air pump output. A belt that is too tight places a severe strain on the water pump, alternator, power steering pump, compressor or air pump bearings.

Replace any belt that is so glazed, worn or stretched that it cannot be tightened sufficiently.

The material used in late model drive belts is such that the belts do not show wear. Replace belts at least every three years.

On vehicles with matched belts, replace both belts. New 1 / 2 inch, 3 / 8 inch and 15 / 32 inch wide belts are to be adjusted to a tension of 140 lbs.; 1 / 4 inch wide belts are adjusted to 80 lbs., measured on a belt tension gauge. Any belt that has been operating for a minimum of 10 minutes is considered a used belt. In the first 10 minutes, the belt should stretch to its maximum extent. After 10 minutes, stop the engine and recheck the belt tension. Belt tension for a used belt should be maintained at 110 lbs. (all except 1 / 4 inch wide belts) or 60 lbs. ( 1 / 4 inch wide belts). If a belt tension gauge is not available, the following procedures may be used.

ADJUSTMENTS FOR ALL V-BELTS




CAUTION
On models equipped with an electric cooling fan, disconnect the negative battery cable or fan motor wiring harness connector before replacing or adjusting drive belts. The fan may come on, under certain circumstances, even though the ignition is off.



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Fig. Fig. 1: To adjust the belt tension or to replace the belts, first loosen the components mounting and adjusting bolts



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Fig. Fig. 2: Move the component toward the engine to remove the belt or away from the engine to tighten the belt



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Fig. Fig. 3: With the component moved towards the engine, you can install the new belt



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Fig. Fig. 4: Pull the component outward and tighten the bolts to adjust the tension



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Fig. Fig. 5: Measure the belts deflection in this manner



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Fig. Fig. 6: Some pulleys have a slot in them to aid in correctly adjusting the belt tension, you could use a breaker bar or large ratchet to hold tension on the belt with these types of pulleys

Alternator (Fan Drive) Belt
  1. Position the ruler perpendicular to the drive belt at its longest straight run. Test the tightness of the belt by pressing it firmly with your thumb. The deflection should not exceed 1 / 4 inch.
  2.  
  3. If the deflection exceeds 1 / 4 inch, loosen the alternator mounting and adjusting arm bolts.
  4.  
  5. Place a 1 inch open-end or adjustable wrench on the adjusting ridge cast on the body, and pull on the wrench until the proper tension is achieved.
  6.  
  7. Holding the alternator in place to maintain tension, tighten the adjusting arm bolt. Recheck the belt tension. When the belt is properly tensioned, tighten the alternator mounting bolt.
  8.  

Power Steering Drive Belt
  1. Hold a ruler perpendicularly to the drive belt at its longest run, test the tightness of the belt by pressing it firmly with your thumb. The deflection should not exceed 1 / 4 inches.
  2.  
  3. To adjust the belt tension, loosen the adjusting and mounting bolts on the front face of the steering pump cover plate (hub side).
  4.  
  5. Using a pry bar or broom handle on the pump hub, move the power steering pump toward or away from the engine until the proper tension is reached. Do not pry against the reservoir as it is relatively soft and easily deformed.
  6.  
  7. Holding the pump in place, tighten the adjusting arm bolt and then recheck the belt tension. When the belt is properly tensioned tighten the mounting bolts.
  8.  

Air Conditioning Compressor Drive Belt
  1. Position a ruler perpendicular to the drive belt at its longest run. Test the tightness of the belt by pressing it firmly with your thumb. The deflection should not exceed 1 / 4 inches.
  2.  
  3. If the engine is equipped with an idler pulley, loosen the idler pulley adjusting bolt, insert a pry bar between the pulley and the engine (or in the idler pulley adjusting slot), and adjust the tension accordingly. If the engine is not equipped with an idler pulley, the alternator must be moved to accomplish this adjustment, as outlined under Alternator (Fan Drive) Belt.
  4.  
  5. When the proper tension is reached, tighten the idler pulley adjusting bolt (if so equipped) or the alternator adjusting and mounting bolts.
  6.  

Air Pump Drive Belt
  1. Position a ruler perpendicular to the drive belt at its longest run. Test the tightness of the belt by pressing it firmly with your thumb. The deflection should be about 1 / 4 inches.
  2.  
  3. To adjust the belt tension, loosen the adjusting arm bolt slightly. If necessary, also loosen the mounting belt slightly.
  4.  
  5. Using a pry bar or broom handle, pry against the pump rear cover to move the pump toward or away from the engine as necessary.
  6.  


CAUTION
Do not pry against the pump housing itself, as damage to the housing may result.

  1. Holding the pump in place, tighten the adjusting arm bolt and recheck the tension. When the belt is properly tensioned, tighten the mounting bolt.
  2.  

SERPENTINE (SINGLE) DRIVE BELT MODELS



Some models feature a single, wide, ribbed V-belt that drives the water pump, alternator, and (on some models) the air conditioner compressor. To install a new belt, loosen the bracket lock bolt, retract the belt tensioner with a pry bar and slide the old belt off of the pulleys. Slip on a new belt and release the tensioner and tighten the lock bolt. The spring powered tensioner eliminates the need for periodic adjustments.


WARNING
Check to make sure that the V-ribbed belt is located properly in all drive pulleys before applying tensioner pressure.

 
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