Westerbeke 3.5 MCGA 60 Hz Operator's Manual page 35

Operator Manual for Gasoline Generators
5.3.4 Cooling System Zinc Anode
A zinc anode (or pencil) in the raw water cooling circuit in the heat exchanger sacrifices itself to
electrolysis action taking place in the raw-water cooling circuit, reducing the effects of
electrolysis on other components of the system. The condition of the zinc anode should be
checked monthly to determine a change interval and the anode cleaned or replaced as
required. Spare anodes should be carried on board.
If the zinc anode needs replacement, hold the hex boss into which the zinc anode is threaded
with a wrench while loosening it with another wrench to avoid potential exchanger damage.
After removing the zinc anode, note its condition. If the zinc is in poor condition, there are
probably zinc flakes within the exchanger. Remove the end of the heat exchanger and clean
the inside of all zinc debris.
Always have a spare heat exchanger end gasket in case the present one becomes damaged
when removing the end cover. Replace the gasket (refer to the heat exchanger end gasket part
number for your engine model). Also replace the O-ring and cover and install a new zinc
anode.
NOTE: The threads of the zinc anodes are pipe threads and do not require sealant. Sealant should not
be used because it may electrically insulate the zinc from the metal of the heat exchanger housing
preventing electrolysis action on the zinc.
5.3.5 Cooling System Thermostat
The thermostat controls the coolant temperature as the coolant continuously flows through
the closed fresh water cooling circuit. When the engine is first started, the closed thermostat
prevents coolant from flowing (some coolant is by-passed around the thermostat to prevent
the exhaust manifold from overheating). As the engine warms up, the thermostat gradually
opens. The thermostat is accessible and can be checked, cleaned, or replaced easily. Carry a
spare thermostat and gasket.
5.3.6 How to Clean the Cooling System Raw Water Intake Strainer
A clean raw water intake strainer is a vital component of the engine cooling system. Include a
visual inspection of this strainer when making your periodic engine check. The water in the
glass should be clear.
NOTE: A properly installed strainer is at or below the waterline so the strainer will always be self-
priming.
Perform the following maintenance after every 100 hours of operation:
1. Close the raw water seacock.
2. Remove and clean the strainer filter.
3. Clean the glass.
4. Replace the washer if necessary.
5. Reassemble and install the strainer.
6. Open the seacock.
7. Run the engine and check for leaks.
NOTE: If you ever run hard aground, follow the above procedure before resuming normal operation.
5.3.7 Raw Water Pump
The raw water pump is a self-priming, non-ferrous housing with a Neoprene impeller. The
impeller has flexible blades which wipe against a curved cam plate within the impeller housing,
5 Maintenance
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