Replacing the Sea Water Pump Impeller
The sea water pump impeller has to be replaced from time to time due to wear. Unscrew the lid, lift out the impeller by hand, or use a screwdriver to help it out. Install the new impeller and close the lid. The wings must be in the same direction!
THE ENGINE ZINC ANODE CAN BE CHECKED AND CHANGED when the system is drained.
Secondary Circuit: Fresh Water System
The fresh water engine coolant circulates through the water jackets around the cylinder block, cylinder head, exhaust manifold, and through the heat exchanger. The rotary pump, driven by the fan belt, is located at the front of the engine. In the tubular heat exchanger (on the starboard side of the engine), the engine coolant is cooled by the sea water.
A thermostat under the expansion tank (marked “Ford Lehman” at the front end of the engine) controls the engine temperature by regulating the rotary speed of the engine coolant.
The total capacity of the fresh water system is 15 liters (14.1 US quarts). The amount of anti-freeze is 50%. Always use anti-freeze, even in the summer, because it contains substances that prevent corrosion. Fill through the expansion tank twist cap.
Overheating Due to a Clogged Sea Water System
If, for some reason, the sea water stops circulating, it will not appear immediately. The engine coolant does not start boiling at once. However, the rubber exhaust hose will soon get overheated.
If you smell burnt rubber or see black smoke coming out of the exhaust pipe, immediately stop the engine and check the exhaust pipe rubber hose and the water strainer of the sea water pump. The cause may be a plastic bag or built-up weed in the strainer, or the sea water pump rubber impeller may have broken down.
The strainer can easily be cleaned by unscrewing the wing nut on top of the vessel and lifting the strainer out. Do not forget to shut the seacock under the strainer. If leaks have occurred in the hose, they can be temporarily mended with cloth, tape, or silicone. But remember to renew the hose, aided by a qualified person, as soon as possible. This applies also to situations when the hose seems “stiff” and has lost its flexibility due to aging. If there is a leak in the exhaust pipe, dangerous exhaust gas will enter into the cabin.
Engine Zinc Anode (Engines Marinized by Lehman)
To prevent electrolysis and corrosion in the seawater system, the engine has been earthed with a zinc anode, placed in the heat exchanger, fastened with a brass bolt.
Fresh Water Cooling Pump Driven by Fan Belt
Important: The fresh water cooling pump is driven by the fan belt. Thus, the system will boil in case of a fan belt failure.
Sea Water Cooling Pump Connected by Engine Shaft
The sea water pump is driven by a pinion connected to an engine shaft cog wheel and is not affected by a broken fan belt.
Buzzer
A buzzer on the instrument panel warns of overheating in the fresh water cooling system.