See Figures 1 and 2
Once a year or at 12,000 mile (19,000 km) intervals, the tension (and condition) of the alternator, power steering, air conditioning, and Thermactor air pump drive belts (as equipped) should be checked. If necessary, the belts should be replaced or 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 components it is driving which will lead to early component failure.
Replace any belt that is so glazed, worn or stretched that it cannot be tightened sufficiently. There are two different types of belts that may be found on your truck, v-belts (single ribbed) and serpentine type (multi-ribbed). Both of these types may drive one or more accessories.
The material used in late model drive belts is such that the belts do not show wear as readily. Replace belts at least every three years.
On vehicles with matched belts, replace both belts. New 1 / 2 , 3 / 8 and 1 /5 33 in. wide belts are to be adjusted to a tension of 140 lbs. and 1 / 4 in. wide belts are adjusted to 7 lbs. (as 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. for all except 1 / 4 in. wide belts or at 60 lbs. for 1 / 4 in. wide belts. If a belt tension gauge is not available, the following procedures may be used.
See Figures 3 through 8
- Position a 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 be between 1 / 4 - 5 / 16 in. (6-8mm).
- If the deflection exceeds these limits, loosen the alternator mounting and adjusting arm bolts.
- Place a 1 in. (25mm) open-end or adjustable wrench on the adjusting ridge cast on the body, and pull on the wrench until the proper tension is achieved.
- 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.
INLINE 6-CYLINDER ENGINES
- Hold 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 within 1 / 4 in. (6mm), and 5 / 16 in. (8mm).
- To adjust the belt tension, loosen the adjusting and mounting bolts on the front face of the steering pump cover plate (hub side).
- Using a large wooden dowel or a pry bar wrapped with a rag to protect the pump hub from damage, carefully pry on the hub in order to 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.
- Holding the pump in place, tighten the adjusting arm bolt and then recheck the belt tension. When the belt is properly tensioned tighten the moun