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 TM 55-1905-220-14-5
3-89. CYLINDER HEAD - MAINTENANCE INSTRUCTIONS.
LOCATION
ITEM
ACTION
REMARKS
a. The cylinder head, one on each cylinder bank, is a one-piece casting securely held to the cylinder block by
special bolts. The exhaust valves, fuel injectors and the valve and injector operating mechanism are located in the
cylinder head.
b. Four exhaust valves are provided for each cylinder. Exhaust valve seat inserts, pressed into the cylinder head,
permit accurate seating of valves under varying conditions of temperature and prolong the life of the cylinder head.
c. To ensure efficient cooling, each fuel injector is inserted into a thin-walled tube, which passes through the water
space in the cylinder head. The lower end of the injector tube is pressed into the cylinder head and flared over; the upper
end is flanged and sealed with a neoprene seal. The sealed upper end and flared lower end of the injector tube prevent
water and compression leaks.
d. The exhaust passages from the exhaust valves of each cylinder lead through a single port to the exhaust
manifold. The exhaust passages and the injector tubes are surrounded by engine coolant. Cooling is further ensured by
the use of water nozzles pressed into the water inlet ports in the cylinder head. The nozzles direct the comparatively cool
engine coolant at high velocity toward the sections of the cylinder head which are subjected to the greatest heat.
e. The fuel inlet and outlet manifolds are cast as an integral part of the cylinder heads. Tapped holes are provided
for connection of the fuel lines at various points along each manifold.
f. To seal compressions between the cylinder head and the cylinder liner, separate laminated metal gaskets are
provided at each cylinder. Water and oil passages between the cylinder head and cylinder block are sealed with
synthetic rubber seal rings which fit into counter-bored holes in the block. A synthetic rubber seal fits into a milled groove
near the perimeter of the block. When the cylinder head is drawn down, a positive leakproof metal-to-metal contact is
assured between the head and the block.
g. Cylinder Head Maintenance
(1) The engine operating temperature should be maintained between 160 - 185F (71 to 85C), and the
cooling system should be inspected daily and kept full at all times. The cylinder head fire deck will overheat and crack in
a short time if the coolant does not cover the fire deck surface. When necessary, add water very slowly to a hot engine
to avoid rapid cooling which can result in distortion and cracking of the cylinder head and block.
3-1448
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