Table 2-1, Mechanical Troubleshooting (Cont)
TEST OR INSPECTION
23. KNOCKS AT IDLE WHEN HOT
Inspect torsional damper for looseness.
If torsional damper is loose,
TM 9-2320-289-20) Insert tool through slot in torsional damper, against front
lip of engine oil pan, to keep crankshaft from turning. Tighten bolt to 200 Ib.-ft.
(271 Nom). Install crankshaft pulley.
Perform Mechanical Troubleshooting malfunction #34.
If pistons are not defective, retarding fuel injector pump timing will quiet
down combustion knock.
Loosen fuel injector pump nuts. Rotate fuel injector pump to retard timing as far as it
will go. Start engine. If knocking is not reduced, loosen any fuel injector line fitting at
fuel fuel injector. Knocking tone will change at fuel line feeding defective piston.
Tighten fitting to 20 Ib.-ft, (27 N.m) with crowfoot attachment J-29698-A and repeat
check until all defective pistons are located. Reset fuel injector pump timing. (See
Remove and inspect any defective pistons, connecting rods, and connecting
rod bearings. (See paragraph 3-1 3)
Remove engine oil pan. (See TM 9-2320-289-20) Check clearance between
connecting rod bearing caps. (See paragraph 3-1 3)
24, EXCESSIVE OIL LOSS
Test compression of each cylinder. (See paragraph 3-2)
Remove, clean, and inspect valves. (See paragraph 3-8)
Repair valves if necessary.
25. OIL PRESSURE LIGHT ON AT IDLE
Remove, disassemble, and inspect engine oil pump and oil filter valve. (See
Check main bearing clearance. (See paragraph 3-1 4)
Remove hydraulic valve lifter clamps and guide plates. (See paragraph 3-9)
Measure hydraulic valve lifter clearance where it contacts its bore, parallel with roller
and 90 degrees to roller. Clearance should not be more than 0,005 in. (O. 130 mm).
Repeat for each hydraulic valve lifter.
Replace hydraulic valve lifters that have excessive clearance.