TM 5-3805-262-34
2-4. ENGINE TROUBLESHOOTING (CONT)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
5. ENGINE NOISY (Cont).
Step 4. (Cont).
b.
c.
d.
e.
Double check by disconnecting fuel injector line connected to
fuel injector installed in suspected faulty cylinder. Noise will
decrease or stop but engine vibration will continue. Reconnect
fuel injector line and repeat this check for remaining cylin-
ders.
Remove engine oil pan (page 3-88) and notify general support
maintenance to check main bearings (page 4-16).
If noise is heard, tell assistant to increase engine speed.
If noise gets louder as engine rpm increases and engine vibra-
tion does not increase as engine rpm increases, connecting rod
insert is worn.
Noise in bad cylinder will decrease or stop when fuel injector
line that goes to bad cylinder is disconnected.
When bad cylinder is located, remove engine oil pan (page 3-88)
and notify general support maintenance to check connecting rod
insert (page 4-42).
If noise is heard, tell assistant to increase engine speed.
If noise does not get louder as engine rpm increases, a camshaft
bushing is worn.
Noise will decrease if fuel injector lines are disconnected at
two or more cylinders and engine is run at high rpm.
Notify general support maintenance to replace camshaft bushings
(page 4-54).
If noise is heard when increasing and decreasing engine speed,
there may be too much lateral movement in crankshaft. A change
in engine rpm will push crankshaft in one direction then in op-
posite direction. Go to step 5 below.
If noise is not heard at cylinder block in line with crankshaft,
go to step 6 below.
Step 5. Remove timing gear cover (page 4-67).
Position dial indicator against crankshaft gear as shown.
Check crankshaft end play using a pry bar between crank throw and
number 2 or 4 main bearing cap.
End play must be 0.003 to 0.015 inch.
2-22
