Operator Manual for Gasoline Generators 5 Maintenance
page 27
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.
If you suspect a faulty thermostat, place it in a pan of water and bring to a boil. A working thermostat should
open about half an inch.
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: Always install the strainer 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, producing the pumping action.
There should always be a spare impeller and impeller cover gasket aboard (an impeller kit).
Raw water pump impeller failures occur when raw water is not present during engine operation. Such failures
are not covered by warranty, and operators are cautioned to make sure raw water flow is present at start-up.
CAUTION: Never allow the pump to run dry. Even a short period of dry running can destroy the impeller.
The raw water pump should be inspected periodically for broken or torn impeller blades. For details, see the
maintenance schedule.
TIP: If the pump internal parts, seals, or bearings fail, it may be more cost-effective to purchase a new pump and rebuild
the original pump to keep as a spare.
If silt, leaves, or grass are caught in the strainer, the flow of raw water through the cooling system may be
restricted and the engine temperature warning light LED might illuminate.
NOTE: The external intake thru-hull opening should be of the flush type with a clear opening with no perforated or slot
type external opening. Allow the filtering to occur on the inside of the hull where there is easy access to the strainer.
5.3.8 How to Change the Cooling System Raw Water Pump Impeller
1.
Close the raw-water intake valve.
2.
Remove the pump cover and, using an impeller puller, screw drivers, or pliers, carefully pry the impeller out of
the pump.
3.
Install the new impeller and gasket.
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