Sea Water Pump, Heat Exchanger - Beta Marine Beta 43 Operator's Maintenance Manual

Yachts and launches with heat exchanger cooling
It is essential that a 33% to 50% anti-freeze/water mixture is
used. This not only stops 'freezing up' in winter, but it
prevents overheating and corrosion.
The warranty is invalid unless the correct ratio is used.
Concentration of ethylene should not exceed 50%.
Sea water pump and cooling system
(Heat exchanger-cooled engines)
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 photo 25.
(2) Withdraw the rubber impeller from its drive shaft as
shown. See photo 25.
25
Cleaning the heat exchanger tube stack and replacing 'wasting zinc anode'
(1) The wasting zinc anode should be checked regularly at
least every six months and replaced every year or as
necessary. The anode is attached to the bolt inserted in
the end cap of the heat exchanger. See photo 26. On
most engines this is on the aft end.
(2) Unscrew the bolt and replace the complete unit with a
new one.
The anti-freeze in the fresh water system enables the boiling
point of water to rise to 124°C with a 13 psi pressure cap
fitted.
The water temperature alarm switch will however be
activated at 95° to 100°C. If no anti-freeze or a very weak
solution is used, then the water temperature switch may not
be activated before coolant is lost.
(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'.
26
(3) 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 photo 27.
(4) Drain off coolant into a bucket.
(5) 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.
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