COOLING
SYSTEM HOSES
Leakage is the most common cooling system trouble.
Besides losing coolant, leaks may also admit air. This
can result in premature failure of the water pump
impeller.
Test all hoses by squeezing and replace any that have
become cracked and brittle or overly
soft.
Verify that
all clamps and connections are tight and check for
leakage. White, rusty, or colored stains indicate
points of previous leakage.
With the generator set running, observe the water
that is discharged from
the
exhaust outlet.* The
presence of air bubbles indicates that air is being
admitted into the sea water system. Tighten all hose
connections as required.
'Cannot
be
observed
if
Aqualifl
muffler
is
used.
EXHAUST
SYSTEM HOSES
Inspect all exhaust system hoses for leaks and
replace any hoses that are cracked and brittle or
overly soft. Rubber hose should be used only in the
water cooled sections of theexhaust. When replacing,
use only rubber hose designed and approved for
marine exhaust use. Provide adequate support for
rubber hose to prevent sagging, bending, and form-
ation of water pockets. Automotive type tail pipe
hangers should be used to prevent vibration from
being transmitted to the hull. Use two hose clamps,
having a minimum width of 1/2 inch (12.7 mm), at
each end of the hose.
inhalation
of
exhaust gases might
result in serious personal
injury
or
death.
Do
not make any sharp bends
in
rubber
exhaust hose when instaiiing as It might cause hose
failure and gas leakage.
The exhaust line should be at least as large as the
engine exhaust outlet and increased one pipe size for
each ten feet of length.
Inhalation
of
exhaust gases might
result in serious personal injury or
death. Pipe exhaust oufside the hull and do
NOT
terminate exhaust pipe nearany window
or
bulkhead
door openings.
ENGINE WATER
JACKET
AND
CYLINDER
HEAD
External coolant leakage may occur at any of the
joints in the engine water jacket such as the drain
plugs, core hole plugs, or cylinder head joints. Since
expansion or contraction can aggravate leakage, the
block should be inspected both hot and cold while
the engine is running.
Internal leakage occurs when coolant passes into the
engin'e oil through a loose cylinder head joint, worn
water pump shaft seal, or a cracked or porous cast-
ing. The leakage is not visible but can causeextensive
damage to the engine. The coolant mixes with the oil
to form sludge which causes lubrication failure.
Heavy sludge accumulations followed by sticking
piston rings, valves, and valve lifters are symptomsof
internal leakage.
Sometimes internal leaks aretight enough to prevent
coolant leakage but permit exhaust gases to enter the
cooling system. The exhaust gases dissolve in the
coolant, depleting the rust inhibitors and forming
acid which causes corrosion.
A
leaking water pump shaft seal can allow water to
enter
the
crankcase on J-series engines with water
pump #132-0147. Refer to
WATER
PUMP
REPAIR
section for pump repair procedure.
DRIVE BELTS
A V-belt
is
used to drive all captive water system
pumps. Belt tension is adjusted by changing the posi-
tion
of
the pump.
inspect the belt periodically and replace if worn or
glazed. Also check to see if the pulleys are properly
aligned and if the belt tension is sufficient.
To adjust the belt, remove the belt guard and loosen
the water pump mounting bolts.Slide the pump back
and forth in the mounting base slots until the correct
belt tension is obtained. There should be a 1/2 inch
(12.7 mm) deflection when a
15
Ib
(67
N)
force
is
applied at the midpoint of the belt. Tighten the mount-
ing bolts when the correct tension is reached and
reinstall the belt guard.
EXPANSION TANK
An expansion tank
is
required with heat exchanger
and keel cooler cooling to allow for coolant expan-
sion and to provide for separation of air from the
coolant. With front-mount heat exchangers and keel
coolers a separate expansion tank is required. With
side mount heat exchangers the expansion tank is an
integral part of
the
heat exchanger. A pressure cap is
fitted to the top of the tank to maintain system
pressure.
32
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by any means, is strictly prohibited.
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