User Manual

20 RENR9968-02
Systems Operation Section
i02414165
Cooling System
SMCS C ode: 1350
This engine has a pressure type cooling system that
is equipped with a shunt line.
A pressure type cooling sys tem offers two
advantages:
•
The cooling system can operate safely at a
temperature th at is hig h er than the norma l boiling
point of water.
•
The cooling system prevents cavitation in the water
pump.
Cavitation is the sudden formation of low pressure
bubbles in liquids by mechanical forces. The
formation of air or steam pockets is more difficult
within a pressure type cooling system.
The shunt line prevents cavitation by the water pump.
The shunt line provides a constant head pressure
at the water pump inlet.
Note: The coolant mixture must be a minimum
of 30 percent ethylene glycol base a ntifreeze for
efficient water pump performance for air to air after
cooled engines. The mixture keeps the cavitation
temperature range of the coolant high enough for
efficient performance.
g01155880
Illustration 16
(1) Cylinder head
(2) Water temperature regulator housing
(3) Expansion tank
(4) Bypass hose
(5) Radiator
(6)Cylinderblock
(7) Engine oil cooler
(8) Transmission oil cooler (if equipped)
(9) Water pump
Waterpump(9)islocatedontherightsideofthe
cylinder block. The water pump is gear-driven from
the front gear group. Coolant can enter the water
pump in two places:
•
Inlet at the bottom of the water pump
•
Bypass hose (4) at the top of the water pump
Coolant from the bottom of the radiator (5) is pulled
into the bottom inlet of the water pump (9) by impeller
rotation. The coolant exits the back of the pump
directly into engine oil cooler (7). Some of the coolant
is also diverted to transmission oil cooler (8) (if
equipped).
Some of the c oolant passes through the core of
engine oil cooler (7) and some of the coolant passes
through the core of transmission oil cooler (8) (if
equipped). The coolant the n enters the inte r nal water
manifold of the cylinder block. The manifold disperses
the coolant to water jackets around the cylinder walls.
From the cylinder block, the coolant flows into
passages in the cylinder heads. The passages send
the flow around the unit injector sleeves and the inlet
and the exhaust passages. T he coolant now enters
water temperature regulator housing (2) at the front
of the cylinder head.