Heat Exchanger; Raw Water Pump; Zinc Electrodes - Northern Lights OM944W3 Operator's Manual

SP-15. HEAT EXCHANGER
1. Clean the heat exchanger core once a year or after
2000 hours of operation.
2. Drain the expansion tank and heat exchanger.
3. Remove the heat exchanger end covers.
4. Clean the inside of the exchanger core tubes using
a metal rod. Flush, inspect, and clean again if
necessary.
5. Reassemble the heat exchanger. Fill the cooling
system. Start the engine and check for leaks.
SP-16. RAW WATER PUMP
1. Change the raw water pump impeller every 500
hours, or as needed.
2. Remove the pump cover. Pry out the impeller using
needle-nose pliers or two screwdrivers. Be sure to
remove all pieces of the failed impeller.
NOTE: Place some kind of protection under the
screwdrivers in order to not damage the
pump housing.
3. Clean the inside of the housing.
4. Press in the new impeller and place the sealing plug
in the outer end of the impeller center if this has not
already been done.
NOTE: Make sure that there is always an extra
impeller and cover gasket in reserve on
board.
Updated 1-6-23
Servicing
SP-17. SIPHON BREAKS
1. If generator set is equipped with a siphon break,
service or clean the siphon break every six months
at minimum, or with every oil change, which ever
comes first. Full details on siphon breaks, and the
requirements for installations below the water line
can be found in Installation Manual IM-1000.
SP-18. ZINC ELECTRODES
1. A zinc electrode is installed in the heat exchanger
cooling system to protect the engine from
electrolysis. Check it faithfully every 250 hours. If
you are in warm saltwater, or where electrolysis is a
known problem, check it more often.
2. Remove the zinc holder from the bottom of the
exchanger. This will drain raw water from the
exchanger.
3. Scrape or steel brush the zinc electrode clean. If
more than 50% of the electrode is corroded away,
replace it with a new zinc. The electrode screws out
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