TM 10-3930-641-34-1
ENGINE TROUBLESHOOTING (CONT)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
8. UNUSUAL ENGINE VIBRATION
Step 1. Inspect engine supports.
a. Tighten all loose capscrews or nuts.
b. Replace defective engine supports. (See page 3-3.)
Step 2. Test fan assembly for fan blade out of balance.
Test procedure:
Remove fan belts and operate engine at speed that had vibration. If there is no vibration, repair
or replace fan assembly. (See TM 10-3930-641-20.)
Step 3. Check pulley or vibration damper for loose bolts.
Tighten bolts on pulley or vibration damper. (See TM 10-3930-641-20.)
Step 4. Check for defects in pulley or vibration damper.
a. Tighten capscrews or replace pulley. (See TM 10-3930-641-20.)
b. Repair/replace vibration damper. (See TM 10-3930-641-20.)
Step 1. See if fuel quality is bad.
a. Replace fuel.
b. Replace fuel filter elements.
Step 2. Inspect fuel injection nozzles for defects.
Step 3. Inspect fuel injection pumps for defects.
Step 4. Check fuel ratio control.
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