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ENGINE MAINTENANCE - 11
COOLING SYSTEM SACRIFICIAL ANODES
Located in the raw water side of the cooling system
are sacraficial anodes which are marked by a decal.
To check, remove the anode and visually check the
condition of the rod. The length of the anode rod when
new is approximately 1.5 inches. If more than one half
of the anode is gone, replace with a new sacraficial
anode.
Different geographic locations and water make-up can
result in either high or low sacrificial requirements. A
high rate of sacrificial anode consumption should also
alert the owner to a possibility of an improperly wired
boat accessory, which would require complete checking
by qualified service personnel.
Figure 11-8 Sacrificial Anode
SACRIFICIAL ANODE LOCATIONS
PCM Raw Water Applications
• One anode is in the rear of each exhaust
manifold.
PCM Fresh Water Applications
• One anode is in the rear of each exhaust
manifold.
• One anode is in the heat exchanger raw water
drain location.
• One anode is in the rear of the Vdrive Housing
for a drain.
• One anode is in each of the exhaust corners for
raw water drain.
28
CHECKING COOLANT LEVEL
Do not remove cooling system filler cap when the
engine is hot. Allow the engine to cool and then
remove the pressure cap slowly, allowing the
pressure to vent. Hot coolant, under pressure, may
discharge violently and cause severe burns.
Degas Bottle
The "see-through" degas bottle is connected to the
heat exchanger by a small hose. The degas bottle
collects coolant that expands with rising temperature,
and would otherwise overflow from the system. Coolant
level should be at or slightly above the "ADD" mark on
the bottle when the system is cold. Coolant should be
added ONLY to the bottle when the system cools. Add
specified coolant as required.
PRESSURE
CAP
Figure 11-9 Checking Coolant Level
TESTING COOLANT FOR ALKALINITY
It is recommended that the coolant in the fresh-water
section be tested each year for alkalinity. Coolant
that is not alkaline has lost the effectiveness of its rust
inhibitors, which can lead to internal corrosion and
cooling system problems. These engines may be
equipped with Sierra propylene glycol based coolant.
The propylene glycol coolant is more environmentally
friendly than ethylene glycol. DO NOT mix ethylene
glycol coolant with propylene glycol coolant. It is
recommended to replace standard propylene glycol
coolant in the system every two years to prevent a
build-up of harmful chemicals within the fresh-water
system.
L510010D-17
WARNING
DEGAS
BOTTLE
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