TM 5-3895-383-24
Aftercooler Coolant Connections
(2) Water temperature regulator housing. (6) Water pump.
(17) Outlet hose. (18) Aftercooler. (19) Inlet hose.
The aftercooler equipped on some engines is tied into the
jacket water coolant system. Inlet hose (19) delivers coolant to
aftercooler (18) from a separate outlet of water pump (6). After
the coolant has circulated through the aftercooler core, it goes
through aftercooler outlet hose (17) and enters regulator
housing (2).
Basic Block
Cylinder Block And Head
The cylinder block has five main bearings for the four cylinder
engine and seven main bearings for the six cylinder engine.
Two bolts hold each bearing cap to the block.
Removal of the oil pan allows access to the crankshaft, main
bearings caps, piston cooling jets, and oil pump.
The camshaft compartment is accessible through covers on
the left side of the cylinder block. These side covers also
support the pushrod lifters. The camshaft is supported by
bearings pressed into the cylinder block. There are five
camshaft bearings for the four cylinder engine and seven
camshaft bearings for the six cylinder engine.
The cylinder head is separated from the block by a steel and
non-asbestos fiber gasket. Coolant flows out of the block
through gasket openings and into the head. This gasket also
seals the oil supply and drain passages between the block and
the head. The air inlet ports are on the top of the head, while
the exhaust ports are located on the right side of the head.
There is one intake and one exhaust valve for each cylinder.
Valve guides are pressed into the cylinder head. The fuel
injector is located between the two valves. Fuel is injected
directly into the cylinders at very high pressure. A pushrod and
rocker arm system controls the valves and fuel injectors.
Pistons, Rings And Connecting Rods
One piece aluminum pistons are used in most applications.
Engines with higher cylinder pressures require two piece
pistons. Refer to the parts book to obtain information about the
type of pistons used in a specific engine.
The aluminum one piece pistons have an iron band for the top
two rings. This helps reduce wear on the compression ring
grooves. Oil from the piston cooling jets spray the underside of
the pistons. This cools the pistons and improves piston and
ring life. The pistons have three rings, two compression rings
and one oil ring. All the rings are located above the piston pin
bore. The oil ring is a standard (conventional) type. Oil returns
to the crankcase through holes in the oil ring groove. The top
two rings are the KEYSTONE type, which are tapered. The
action of the ring in the piston groove, which is also tapered,
helps prevent seizure of the rings caused by too much carbon
deposit.
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