Beta Marine Beta 10 Operator's Maintenance Manual page 25

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Heat Exchanger Cooled
Fresh water 'coolant' circulates through the engine and then the heat exchanger body where the engine heat is transferred to
the sea water that is pumped through the heat exchanger cooling tubes (tube stack). The heated sea water is then injected into
the exhaust system (see diagram).
Yachts and Launches with Heat Exchanger Cooling
It is essential that a solution of fresh water and anti-freeze is
used as engine coolant. The amount of anti-freeze must be
between 33% to 50%. This not only stops 'freezing up' in
winter, but it prevents overheating and corrosion.
The warranty is invalid unless the correct ratio is used.
The concentration of ethylene must NOT exceed 50%.
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 sooner,
as necessary. The anode is attached to the bolt inserted
in the end cap of the heat exchanger. See photo 31. On
most engines this is on the aft end.
(2) Unscrew the bolt and replace the complete unit with a
new one, 209-61840. Check for leaks.
(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 32 .
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°C 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.
31
Zinc anode
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