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6 Avoid unscrewing the expansion tank cap
when the engine is hot, but if this must be
done, cover the cap with a cloth to avoid
scalding by escaping steam.
7 Periodically, check the condition of all
coolant hoses and tighten the clips.
2 Cooling system - draining,
flushing and refilling
1
1 Set the heater temperature lever to
maximum.
2 Unscrew the cap from the expansion tank.
3 Disconnect the radiator bottom hose and
unscrew the cylinder block drain plug (1116
cc and 1301 cc engines) and allow the coolant
to drain. Refer to photo 29.21B, page 64.
4 If the system is in good condition with no
sign of rust or dirt in the drained coolant, then
it may be refilled immediately. If the system
has been neglected and the antifreeze has not
been regularly renewed and there is evidence
of rust and sediment in the drained liquid then
flush the system through with a cold water
hose.
5 If the radiator should appear to be clogged,
it may be necessary to remove it (Section 7)
invert it and reverse flush it using a cold water
hose. If, after a reasonable period the water
still does not run clear, the radiator should be
flushed with a good proprietary cleaning
system. Extensive damage should be repaired
by a specialist or the unit exchanged for a
new or reconditioned radiator.
6 Reconnect the bottom hose and screw in
the drain plug.
7 Remove the plug (B) (Fig. 2.2) from the
bleed hole in the heater hose.
8 Remove the plug (D) (Fig. 2.3) from the
bleed hole in the expansion tank.
9 Pour antifreeze mixture slowly into the filler
neck of the expansion tank until it is seen to
come out of the expansion tank plug hole.
Screw in the plug.
10 Add further coolant until it is seen to
dribble out of the hole in the heater hose.
Screw in the plug.
11 Top up the expansion tank to the
specified level and screw on the tank cap.
12 Start the engine and run it until the cooling
fan cuts in. Switch off, allow to cool and top
up if necessary to the specified mark on the
expansion tank.
3 Coolant mixtures
1 In cold climates, antifreeze is needed for
two reasons. In extreme cases, if the coolant
in the engine freezes solid it could crack the
cylinder block or head. But also in cold
weather, with the circulation restricted by the
thermostat, and any warm water that is
getting to the radiator being at the top, the
bottom of the radiator could freeze, and so
block circulation completely, making the
coolant trapped in the engine boil.
2 The antifreeze should be mixed in the
proportions advocated by the makers,
according to the climate. There are two levels
of protection. The first cuts risk of damage, as
the antifreeze goes mushy before freezing.
The second, valid all year round, is the
corrosion protection it offers - see below. The
normal proportion in a temperate climate to
provide maximum protection against freezing
and corrosion is 50% antifreeze and
50% water.
3 Use only ethylene glycol based antifreeze
and preferably soft water.
4 Antifreeze should be left in through the
summer. It has an important secondary
function, to act as an inhibitor against
corrosion. In the cooling system are many
different metals, in particular the aluminium of
the cylinder head. In contact with the coolant
this sets up electrolytic corrosion,
accentuated by any dirt in the system. This
corrosion can be catastrophically fast.
5 After about two years, the effectiveness of
the antifreeze’s inhibitor is used up. It must
then be discarded, and the system refilled
with new coolant.
6 In warm climates free from frost, an
2•2 Cooling and heating systems
Fig. 2.3 Plug (D) in expansion tank (Sec 2)Fig. 2.2 Plug (B) in heater hose (Sec 2)
1.5 Expansion tank cap
Fig. 2.1 Cooling system on 903 cc engine (Sec 1)