21
Cooling System
Capacity 32 pints (Imp.) 38 pints (U.S.) 18.2 litres.
The coolant is circulated by a centrifugal pump driven off the engine, by the same belt as the alternator.
A thermostat is fitted, immediately above the water pump, to assist in rapid warming up of the engine.
WARNING
The cooling system is pressurised to 14 p.s.i. and therefore operates at a higher
temperature than normal. Scalding could result if radiator filler cap is removed when the engine is
hot. All checks should therefore be made when the engine is cool or cold.
Topping up
Coolant level should be checked daily. When necessary clean water should be added to bring the
level in the radiator up to the indicator bar in the header tank. The radiator should not be over-filled,
as the pressurised system requires room for expansion.
Cold water
MUST NOT
be added when the engine is hot, other-wise serious damage may be caused
to the engine. It must either be allowed to cool down, or hot water added to the radiator.
Draining Cooling System
There are 3 draining points; one at the bottom of the radiator, and one at each side of the crankcase,
at the base of each cylinder block. It is essential that all three be opened when draining the engine.
The radiator drain tap may become clogged with sediment, and should therefore be cleaned
occasionally with a piece of stiff wire.
Frost Precautions
In cold weather there is a risk of the water freezing and cracking the cylinder block or radiator.
Therefore, an anti-freeze solution should be used under these conditions. It is essential that only an
Ethylene Glycol-based product be used. For the correct quantities to add, for full protection under
different weather conditions, reference should be made to the anti-freeze makers’ charts.
Flushing
To reduce the formation of deposits, which impair efficiency, the cooling system should be flushed
out with clean water every 5,000 miles. This is particularly important before adding anti-freeze.
Thermostat
The thermostat restricts flow between the cylinder block and radiator to assist rapid warming up. It is
of the copper-impregnated wax type, and should start to open at approximately 57°C. It should be
fully open at approximately 75°C. Failure of the thermostat is indicated by slow warming up, and poor
heater performance.
Electric Fans
There is no engine driven cooling fan, but in its place two electric fans which operate only when
required to maintain optimum engine operating temperature. These fans are mounted on the cross
tube behind the radiator and are controlled by a thermostatic switch in the bottom of the radiator.
They are not wired through the ignition circuit and will therefore continue running, if necessary, even
after the engine has been switched off. (This is because the water temperature actually rises during
the last few seconds of a journey, owing to the car being stopped and there being no air flow through
the radiator. The fans will only run for a very short time, and then switch themselves off).
The fans are protected by a fuse in the Relay Box at the rear of the engine compartment.
