ENGINE REPAIR INSTRUCTIONS
Section I. CYLINDER HEAD AND VALVES
heavy engine oil through spark plug hold to seal pistons
and repeat test.
a. The cylinder head is an alloy cast iron unit
(1) To check piston blow-by, remove engine oil filler
secured to the engine block with special hardened studs
cap. Crank engine, and as the piston is slowly brought
and screws. The head seals the top end of the cylinders
to compression listen at the oil filler tube. If piston is
to form the combustion chambers, and has passages for
allowing air to leak past, it can be heard.
the intake of the air-fuel mixture, and the expulsion of
(2) Mark cylinder for piston repair.
exhaust gases, as well as cored passages through which
the coolant flows to prevent overheating.
b. The cylinder head as well as the valve tappet
cover must be removed to gain access to the valves
and valve springs. The end of each valve stem is fitted
with a shallow steel retainer that surrounds the end of
the valve spring, and is held to the stem by a pair of
wedge keepers or locks.
a. Refer to TM 10-3930-630-12 and remove the
11-2. Cylinder Compression Check
a. Refer to TM 10-3930-630-12 and remove spark
b. Remove the valve locks, valve springs,
plugs and check compression in each cylinder using a
retainers, valves and valve springs as illustrated in
compression tester and gage. Crank engine to check
Figure 11-1. Checking cylinder compression.
b. Note reading on each cylinder. Pressure of
cylinders must be within 10 psi (0.703 kg/cm2) of each
c. Note cylinders that vary from tolerance. These
cylinders will have to be repaired.
d. If it is suspected that compression may be
Figure 11-2. Values, removed and installation .
leaking past piston rings, inject small amount of
c. After valves are removed, remove tappets (9),