Pleasurecraft Marine Pleasurecraft 302/2A Owner's Manual - Cooling Systems
COOLING SYSTEMS
The cooling system of each PCM Marine Engine
incorporates a full circulation bypass system, permitting a
ful flow of water through the engine, even during warmup.
Two heavy-duty marine-type pumps are used to accomplish
this. A flexible impeller supply pump is used to keep the
system full, and cool the exhaust system; a high volume
circulating pump maintains full water circulation to prevent
steam pockets and hot spots, and assure longer valve and
piston ring life. A heavy-duty thermostat is used to control
the amount of water which is discharged from the engine
after temperature is reached. The discharged water is
automatically replaced by cool water from the supply pump,
maintaining an unusually stable engine temperature through
an exceptionally simple system. The hot water is discharged
into the exhaust manifold water jackets, pre-heating the
manifold to reduce condensation.
Should overheating occur, stop the engine immediately.
Check the water intake for obstruction by weeds, etc.
(Plastic sandwich bags and similar containers effectively
close off a water intake - don't litter.) Check water pump
drive belts for tension and slippage. Inspect water intake
hoses for kinks and bends.
On inboard and vee-drive models, check the transmission oil
cooler for obstruction of the water tubes.
On all 255 H.P. models equipped with engine oil cooler,
check the engine oil cooler for obstruction of the water
tubes.
A partial inspection of the flexible impeller of the supply
pump can be made by removing the top hose from the
supply pump, and looking into the pump chamber while
slowly turning the pump pulley. A badly damaged impeller
should be readily detected in most cases.
If a problem is found and corrected, do not attempt to restart
until the engine has cooled to normal limits.
See lay-up instructions for inspection and/or replacement of
the supply pump impeller.
In freezing weather, the cooling system must be drained of
all water to prevent damage. Drains are located on both sides
of the engine block, exhaust manifolds, oil coolers, (if so
equipped) and the elbow beneath the circulating water pump.
On inboard and vee-drive models, the drain on the
transmission oil cooler should be opened or the lower hose
removed.
On all 255 H.P. models equipped with the engine oil cooler
it should be drained.
On all fresh water cooled models, with closed cooling
systems, an anti-freeze solution of 50% permanent type
antifreze, such as Zerex or Prestone should be used. This
solution should be left in the system, and replaced once a
year as an annual maintenance item. It is not necessary to
drain these systems during freezing weather or lay-up,
except for the following items:
A. Exhaust Manifolds.
B. Engine Oil Cooler - if so equipped.
C. Transmission Oil Cooler - if so equipped.
D. Raw Water Pump.
E. Heat Exchanger - sea water portion only.
F. All Hoses Which Carry Raw Water.
See Lay-up Instructions, Page 31 for full details.
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