Cooling System (External) - Westerbeke WPDS-20 Technical Manual

SECTIONR
COOLING SYSTEM (EXTERNAL)
1. DESCRIPTION
The 4 and 6 cylinder marine diesel engines are equipped with a fresh water
cooling system. Transfer of heat from the fresh water (closed system) circuit to
the sea (raw) water is accomplished by a heat exchanger, similar to an automobile
radiator. It differs because raw water, not air, cools the engine's fresh
water. An unrestricted fast-flowing stream of sea water flows through the
tubes of the heat exchanger while the fresh water flows rapidly under low pressure
around the tubes of the heat exchanger. The raw water and fresh water never mix
so the water cooling passages in the engine stay clean.
20
FRESH WATER SYSTEM
Heat rejected in combustion, as well as heat developed by friction is
absorbed by the fresh water. The fresh water flows from the expansion tank to the
heat exchanger; here it is cooled and discharged into the lower part of the
cylinder block, where it is circulated through the block and cylinder head by
means of a centrifugal fresh water pump. Openings in the water jacket around
the cylinder bores connect with corresponding openings in the cylinder head, where
the fresh water ci rcul ates around the val ves and Juel injectors. When the
engine reaches its operating temperature, the fresh water then passes out
through the thermostat into the expansion tank and the circuit repeats.
SURGE
TANK
FRESH
WATER
PUMP
RAW
WATER
PUMP
FROM SEA
COCK
EXHAUST
MANIFOLD
I - . . .
- - ¥ ...... ,
OIL
0
FILTER
-~-
lOVER
--lBOARD
HEAT
EXCHANGER
-, FROM
r
)=<P
Cl Cl
<J::!
SE A
~~--~~
COCK
~ ~
RAW WATER
> >
FRESH WATER
~- - . -
ENGINE OIL
r-~
IUSED
ON HYD-
HYDRAULIC GEAR/1:J.'/CXSJ
t::l
RAU L IC GEAR
OIL COOLER
If
ONLY