TM 5-3810-300-24 & P3
1.1
CYLINDER BLOCK
Since the cylinder block is the main structural part of the
The cylinder block (Figs. 1 and 2) serves as the main
engine, the various sub-assemblies must be removed from the
structural part of the engine. Transverse members, cast
cylinder block when an engine is overhauled.
integrally, provide rigidity and strength and ensure alignment
of the block bores and bearings under load. The two ends of
The hydraulically operated overhaul stand (Fig. 5) provides a
the block are similar, so the flywheel housing and gear train
convenient support when stripping a cylinder block. The
can be assembled to either end.
engine is mounted in an upright position. It may then be
tipped on its side, rotated in either direction 90 or 180 where it
The block is bored to receive replaceable cylinder liners.
is locked in place and then, if desired, tipped back with either
Water jackets, which extend the full length of the bores, are
end or the oil pan side up.
divided into upper and lower sections which are connected by
hollow struts (Fig. 2). Coolant from the pump enters at the
bottom of each water jacket and leaves at the top of the block
Remove and Disassemble Engine
through holes which register with corresponding openings in
the cylinder head.
Before mounting an engine on an overhaul stand, it must be
removed from the vehicle and disconnected from the
An air box (Fig. 2) surrounding the water jackets conducts the
transmission. Details of this procedure will vary from one
air from the blower to the air inlet ports in the cylinder liners.
application to another. However, the following steps will be
Air box openings (Fig. 3) on the side of the block opposite to
necessary.
the blower provide access to the air box and permit inspection
of the pistons and compression rings through the air inlet ports
1. Drain the cooling system.
in the cylinder walls. The six-cylinder block has two additional
air box openings on the blower side.
2. Drain the lubricating oil.
The camshaft and balance shaft bores are located on opposite
sides near the top of the block.
The upper halves of the main bearing supports are cast
integral with the block. The main bearing bores are line-bored
with the bearing caps in place to ensure longitudinal
alignment. Drilled passages in the block carry the lubricating
oil to all moving parts of the engine, eliminating the need for
external piping.
The perimeter of the top surface of the cylinder block is
grooved, outside of the cam pockets, to accommodate a
block-to-head oil seal ring. The top surface of the block is also
counterbored at each water or oil passage to accommodate
individual seal rings (Fig. 4).
Each cylinder liner is retained in the block by a flange at its
upper end. The liner flange rests on a cast iron insert located
in the counterbore in the block bore.
An individual
compression gasket is used at each cylinder.
When the cylinder head is installed, the gaskets and seal rings
compress sufficiently to form a tight metal to-metal contact
between the head and block.
New service replacement cylinder block assemblies include
the main bearing caps and bolts, dowels and the necessary
plugs.
Fig. 1 - Typical Cylinder Block
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