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TM 5-4320-305-24
Table 4-1. General Support Maintenance Troubleshooting
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1. ENGINE IS HARD TO START
Step 1. Check for sticking or burned exhaust valves. Inspect valves.
Repair or replace faulty valves (para 4-7).
Step 2. Check for broken or worn piston rings. Inspect pistons and rings. Inspect cylinder
head assembly.
Repair or replace pistons (para 4-10) and cylinder head assembly (para 4-6 or
3-19). Replace piston rings (para 4-10).
Step 3. Check for improper exhaust valve clearance.
Check and adjust exhaust valve clearance (para 4-7).
2. ENGINE CONSUMES EXCESSIVE LUBE OIL (MAY PRODUCE BLUE SMOKE)
Step 1. Check for worn or broken double-chamfered rings. Inspect pistons and rings. Inspect
cylinder head assembly.
Repair or replace faulty pistons (para 4-10) and cylinder head assembly (para
4-6 or 3-19). Replace piston rings (para 4-10).
Step 2. Check for scored cylinders or pistons. Inspect cylinders and pistons.
Repair or replace faulty cylinder head assembly (para 4-6 or 3-19) and piston
(para 4-10).
Step 3. Check for loose piston pin circlips. Inspect piston pin circlips.
Replace a loose piston pin circlip (para 4-10).
Step 4. Check for piston and connecting rod alinement. Inspect pistons and connecting rods.
Check crankshaft thrust surfaces for wear or grooving.
Replace a faulty piston (para 4-10) or connecting rod (para 4-11). If necessary,
replace crankshaft (4-12).
3. ENGINE PRODUCES EXCESSIVE CRANKCASE PRESSURE
Step 1. Check for worn piston rings, a hole or crack in a piston crown, or excessive exhaust
back pressure.
Replace worn or damaged parts (para 4-10).
4. ENGINE HAS LOW OIL PRESSURE
Step 1. Check for excessive wear on crankshaft bearing journals or main bearings. Inspect
crankshaft and main bearings.
Replace faulty crankshaft or main bearings, if necessary (para 4-12 and 4-13).
4-3
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