TM 5-1940-322-10
0003 00
THEORY OF OPERATION (Contd)
FUNCTION OF ENGINE COOLING SYSTEM
The engine cooling system is identical on both port and starboard engines. Coolant is
pumped through the primary cooling systems using a water pump. The water pump
draws coolant from three locations: water pump supply hose attached to keel cooler,
exhaust manifold cooler return hose, and reservoir tank draw hose.
Coolant is pumped through the engine block and routed to the following locations:
a. Through thermostat housing, keel cooler supply hose, and back to keel cooler
b. Through exhaust manifold, exhaust manifold cooler return hose, and back to
water pump
c. Through engine block air bleed return line and back to coolant reservoir
tank
d. Through exhaust manifold air bleed return line and back to coolant
reservoir tank
e. Through turbocharger supply line, turbocharger, turbocharger air bleed
return hose, and back to coolant reservoir tank
f. Through keel cooler supply hose, thermostat air bleed return hose, and back
to coolant reservoir tank
FUNCTION OF RAW WATER COOLING SYSTEM
The port and starboard engines have their own separate raw water cooling systems.
The raw water cooling system cools the transmission oil and exhaust pipes and
allows for raw water to flush the keel cooler area.
High-pressure raw water supplied from the hydrojets circulates using two paths:
1. Path One: High pressure raw water from hydrojet is circulated through raw
water strainer supply hose, into raw water strainer, raw water
transmission oil cooler supply hose, transmission oil cooler, wet
exhaust supply hose, and wet exhaust pipe elbow, and overboard
through exhaust port.
2. Path Two: Raw water supplied from hydrojet is circulated through keel cooler
raw water flush hose, into keel cooler connection, and out to raw
water underneath hull. This prevents still water heat-up near keel
cooler.
0003 00-2
