Cooling System -807640122

TM 9-2320-312-24-2

Systems Operation Section

Crankshaft main bearings

The bypass valves (22) and (18) will open when

the engine is cold (starting conditions). Opening

Turbocharger cartridge

the bypass valves achieves immediate lubrication

of all components. Immediate lubrication is critical

when cold oil with high viscosity causes a restriction

An oil cooling chamber is formed by the lip that is

to the oil flow through engine oil cooler (23) and

forged at the top of the skirt of the piston and the

engine oil filter (21). The engine oil pump (24) sends

cavity that is behind the ring grooves in the crown.

the cold oil through the bypass valves around the

Oil flow for the piston cooling jet enters the cooling

engine oil cooler (23) and engine oil filter (21) to the

chamber through a drilled passage in the skirt. Oil

turbocharger oil supply line (15) and the main oil

flow from the piston cooling jet returns to the engine

gallery (14) in the cylinder block.

oil pan (27) through the clearance gap between the

crown and the skirt. Four holes that are drilled from

When the oil gets warm, the pressure difference

the piston oil ring groove to the interior of the piston

in the bypass valves decreases and the bypass

drain excess oil from the oil ring.

valves close. After the bypass valves close, there

is a normal flow of oil through the engine oil cooler

and the engine oil filter.

The bypass valves will also open when there is a

restriction in the engine oil cooler (23) or engine

oil filter (21). This design allows the engine to be

lubricated even though engine oil cooler (23) or

engine oil filter (21) are restricted.

The engine oil cooler bypass valve is also activated

by pressure. If the oil pressure differential across

the engine oil cooler reaches 125 30 kPa

(18 4.5 psi), the valve will open. Opening the valve

allows the oil flow to bypass the engine oil cooler

g00292663

(23).

Illustration 34

Front Left Side View Of Engine

The main oil flow now reaches the main engine oil

(29) Breather. (30) Hose. (31) Valve cover.

filter (21). When the oil pressure differential across

the oil filter bypass valve (18) reaches 125 30 kPa

Breather (29) allows engine blowby to escape from

(18 4.5 psi), the valve opens in order to allow

the crankcase. The engine blowby is discharged

the oil flow to go around the oil filter (21). The

through hose (30) into the atmosphere. This

oil flow continues in order to lubricate the engine

prevents pressure from building up that could cause

components. When the oil is cold, an oil pressure

seals or gaskets to leak.

difference in the bypass valve also causes the valve

to open. This bypass valve then provides immediate

lubrication to all the engine components when cold

i00665400

oil with high viscosity causes a restriction to the oil

Cooling System

flow through the engine oil filter (21). The bypass

valve will also open when there is a restriction in the

SMCS Code: 1350

engine oil filter (21). This design allows the engine

to be lubricated even though engine oil filter (21)

This engine has a pressure type cooling system that

is restricted.

is equipped with a shunt line.

Note: Refer to Specifications, "Engine Oil Filter

A pressure type cooling system offers two

Base".

advantages:

Filtered oil flows through the main oil gallery (14) in

The cooling system can operate safely at a

the cylinder block. Oil is supplied from the main oil

temperature that is higher than the normal boiling

gallery (14) to the following components:

point of water.

Piston cooling jets (8)

The cooling system prevents cavitation in the

water pump.

Valve mechanism

Camshaft bearing (12)