Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual

Page: 32 / 413

2nd re-Issue
Pa1e 2
WSM.124
Section A (Cooling System)
COOLING SYSTEM
All threads are of the Unified series and the appropriate spanners must be used
GENERAL DESCRIPTION
Water Is circulated by an · lmpellor type pump
mounted on the front of the cylinder block. It Is
driven by a vee belt which also drives the generator.
The radiator cooling fan Is bolted to the pump­
driving pulley.
Alpine
Service I and II
A cross flow radiator is used on these cars.
Water Is drawn from the bottom end of the
right-hand (offside) vertical tank of the radiator
and delivered Into the cylinder block where it
passes around the cylinder barrels. From the
cylinder block the water flows into the cylinder
head through one brass water jet and several
water holes. The brass jet Is used to direct the
clrculatlon of water in the cylinder head.
Water passes from the cylinder head into the
thermostat housing, and when the thermostat
valve Is open, Into an aluminium header tank
that Is bolted to the thermostat housing
Immediately above the thermostat. The header
tank Is coupled to the top end of the left-hand
(nearside) vertical tank of the radiator by the
top water hose.
Rapier models and Alpine
Serles
Ill
A vertical type of radiator Is used on these cars.
Water Is drawn from the bottom tank of the
radiator through the bottom water hose by
the water pump, and passes through the engine
to the thermostat housing In exactly the same
way as described above. It then flows through
the top water hose to the radiator top tank.
Whenever possible clean rainwater, or so�ened water
should be
used, In preference to tap water.
The cooling system Is not required to come Into full
operation until the engine has attained Its normal
working temperature, and It Is desirable that this
should be brought about as quickly as possible
after starting the engine from cold.
To accomplish this, a thermostatically operated
valve Is located In a cast-iron body bolted to the
front end of the cylinder head.
The thermostat valve remains closed when the
engine Is cold, and when the engine Is started from
cold, water returns to the pump intake through a
small by-pass pipe which connects the pump Intake
pipe with the engine side of the thermostat valve.
Water also flows through a pipe from the rear end of
the cylinder head to the water-heated Induction
manifold jacket and from here to the suction side
of the water pump.
After starting the engine, the water temperature
will rapidly rise, but circulation of the water
through the radiator does not commence until a
suitable temperature has been reached In the
cylinder head, cylinder block water jackets, and
induction manifold Jacket.
At this temperature the thermostat begins to open
and water commences to flow through the radiator.
The ther.mostat becomes fully open at the normal
operating temperature.
The thermostat operating temperatures are given
In the Data Section under "Cooling System".
Radiator Relief Val.,e (See Fig. 1)
Incorporated In the filler cap is a spring­
loaded relief valve which prevents water loss
through the overflow pipe when the water Is at
normal level.
In addition, this valve allows a small pressure to
build up In the cooling system. This raises the
boiling point of the water which Is a great advantage
in high altitudes and In tropical conditions.
As the cooling system temperature falls partial
vacuum Is formed. This is relieved by entry of air
through the overflow pipe and the facuum release
valve which Is built Into the pressure relief valve.
Details of the relief valve release pressures are
given In the General Data Section under "Cooling
System".
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