Sea Water Pump, Heat Exchanger

CAUTION

Before working on the sea water system ensure that the sea cock is in the off position. (1)It is very important that the correct sea water flow is maintained to cool the closed circuit system of the engine. The key component in this system is the sea water pump impeller.

This should be checked every year by removing the circular plate (see fig. 2h) (2) Withdraw the rubber impeller from its drive shaft as shown.

See diagram 2i. (3)Check impeller for cracks in the rubber, excessive wear or lost vanes. Replace with a new impeller as necessary. Note: If any pieces of rubber impeller are missing then they must be found as they are most likely to be trapped in the entrance to the heat exchanger cooling stack. See ‘Cleaning Tube Stack’.

Fig. 2h

Fig. 2i

CLEANING THE HEAT EXCHANGER TUBE STACK AND REPLACING WASTING ZINC ANODE

(1) The wasting zinc anode should be checked every six months and replaced every year or as necessary. The anode is attached to the bolt inserted in the aft end cap of the heat exchanger. See fig. 2j. (2)Unscrew the bolt and replace the complete unit with a new one. (3)Check for leaks. (4) It is possible for fine sea weed and other debris to get past the inlet filter and into the tube stack.

This should be removed and cleaned. See fig. 2k. (5)Drain off coolant into a bucket. (6) Unscrew the 2 end cap retaining bolts (one each end of the tube stack). Remove the ‘O’ rings and pull out tube stack. Clean tube stack and end caps. (7) Re-assemble using new ‘O’ rings.

Do not overtighten end cap bolts and make sure the tube stack is the right way round. (8) Re-fill engine with water/antifreeze solution and run engine up to temperature to check for leaks.

Zinc Anode Fig. 2j

Fig. 2k