Procedure A - Engine Accessories, Belts, Pulleys

1. After confirming vibration RPM and proper engine tune, stop engine.

2. Carefully inspect engine accessory drive belts and pulleys for damage, misalignment, and wear. Correct as necessary.

Drive Belt:

3. Check and adjust drive belt tension and accessory mounting tightness.

Idle:

4. Start engine and allow it to idle. Observe operation of belts and pulleys and listen for abnormal noise. Watch carefully for irregular motion of belts. If belts are found to be shaking, wavering or jumping, replace belt and recheck. If irregular motion continues, check for pulley runout, flange width uniformity and for proper accessory operation. Correct as necessary and recheck vibration.

Increase Engine Speed:

5. Increase engine speed to vibration RPM. Again, observe belts for proper operation. Listen carefully to each component to locate cause of vibration. Remove suspected accessory belt to verify.

Drive Belts:

6. If vibration persists, stop engine and remove drive belts one at a time. Recheck vibration after each belt is removed. When vibration is eliminated, repair accessory system last disconnected.
CAUTION: Be careful to avoid engine overheating when operating with water pump and/or fan disconnected.

7. To repair accessory system, install new belt and check mounting. If still bad, repair/replace accessory unit as necessary.