TM 5-6115-400-12
Figure 3-10 (3). Continued.
Section VII. ENGINE VALVE MECHANISM
Caution: After any mechanical work has been done
3-22. General
Insufficient valve clearance can cause loss of
which would disturb the valve adjustment, make
compression, misfiring, and will eventually cause
certain that the adjusting screws in the rocker arms
burning of the valves and valve seats. Excessive valve
are turned upward (counterclockwise) high enough
clearance will result in faulty engine operation, valve
so that the rocker arms and push rods will not open
lifter noise, and rapid wear of the valve operating
the valves too far and thus allow the pistons to
mechanism.
strike the valves when the engine is cranked.
With the engine at normal operating
3-23. Valve Clearance Adjustment
temperature (180F. minimum), the specified valve
clearance is .015 inch for the intake valves and .020
The valve lash must be adjusted when piston is
inches for the exhaust valves. After any mechanical
near top dead center on its compression stroke and the
work has been done which would disturb the valve
intake and exhaust valves closed. No. 1 and No. 6
clearance, the intake valves may be set cold at .018
pistons move up and down in their respective cylinders
inches and the exhaust valves at .023 inches so the
simultaneously and when one piston is on its
engine may be run and allowed to warm up. After
compression stroke, the other piston is on its exhaust
engine has reached normal operating temperature the
stroke, and vice versa. Observe valves for No. 6
valve clearance should again be checked. Refer to
cylinder; when exhaust valves are nearly closed and
figure 3-11 for valve location.
intake valves start to open, the
3-18
