TM 5-3810-288-12
7-49. Engine Compression Test
Test the engine compression as follows:
a. Blow all foreign material from around the spark
plugs with compressed air. Loosen all spark plugs one
turn. Start the engine and run at a fast idle for a few
minutes.
b. Stop the engine and remove all the spark plugs.
Refer to figure 7-15 and disconnect the air cleaner hose
from the carburetor intake. Refer to figure 6-1 and pull
the throttle control out fully.
c. Insert a compression gage firmly in a spark plug
opening and crank the engine through four or five
compression strokes with the starter. Read the amount
of compression on the gage.
d. Repeat the above step for the remaining cylinder.
The compression gage reading for all the cylinders
should be between 125 and 145 psi (pounds per square
inch). If the compression of any cylinder does not fall
within this range, re-port the deficiency to General
Support Maintenance.
7-50. Engine Rocker Arm-Tappet Adjustment
a. General. The tappets on this engine are to be
adjusted when the engine has set idle for a period of
time so that it has cooled to the temperature of the
surrounding air. They can not be accurately set if the
rocker arms are hollowed out by contact with the valve
pushrods. If inspection reveals hollowed out rocker
arms, report the condition to proper authority.
b. Adjustment. Adjust as follows:
(1) Remove the spark plugs from the engine so
that it can be turned to the required crankshaft positions.
Figure 7-49. Windshield wiper motor, removal and
(2) Refer to figure 7-53 and remove the valve
replacement. (Sheet 2 of 2)
tappet cover. Note that the eye bolts shown are for
removing cylinder heads only. The eye bolt shown in
b. Exhaust Manifold.
(1) Inspection. Inspect the exhaust manifold for
the engine from the machine.
loose nuts, leaks, cracks, or other physical damage.
(3) Insert a suitable rachet extension into the
and replace the exhaust manifold.
socket in the front of the vibration damper and turn the
(3) Repair.
Repair the exhaust manifold by
engine over until the mark on the engine flywheel
replacing any damaged exhaust manifold components.
indicates that number one piston is on top dead center
Refer to figure 7-51 and replace any damaged exhaust
on the compression stroke.
manifold components.
Refer to figure 3-29 for vibration damper location
7-48. Exhaust Pipe and Muffler
Refer to figure 7-52 and remove and replace the
exhaust pipes and muffler.
7-57
