Servicing the systems
- Cooling: change the raw-water impeller, check the anodes, inspect the heat exchanger, and check the coolant strength and level.
- Lubrication: change the oil and filter with the engine warm, check for emulsified (milky) oil that signals water ingress, and use the correct grade.
- Transmission: check the gearbox oil, the coupling and the stern gland or shaft seal, and grease or adjust as required.
- Belts and pulleys: check alignment, tension and wear, and carry spares.
Changing the raw-water impeller
Renewing a raw-water impeller
- Shut the raw-water seacock so the sea cannot flood in.
- Remove the pump cover, note the impeller's orientation, and ease the old impeller out.
- Fit the new impeller the correct way round, lightly lubricated, with a new gasket or O-ring.
- Refit the cover, open the seacock, start the engine and confirm cooling water at the exhaust; account for any vanes lost from the old impeller.
WARNING — Account for every vane If the old impeller has lost vanes, find them — they lodge in the heat exchanger and cause overheating if left behind. Never refit the cover until you know where every piece went.
NOTE — Milky oil means water has got in Emulsified, milky oil on the dipstick means water has entered the lubrication system, from a leak or a cooling fault. Investigate the cause before running the engine on.