Perkins 4.99 - SECTION M Cooling System; Fan Belt Procedures; Water Pump Overview and Removal

The engine is cooled by water circulation through
passages in the
cylinder block and cylinder head. Cir-
culation is by thermo-syphon action, assisted by an
impeller type water pump, belt driven from the crank-
shaft pully.
FAN BELT
To Adjust the Fan Belt
Fan belt adjustment is achieved by altering the posi-
tion
of the generator as detailed below.
1. Slacken the
generator adjusting lever setscrew.
2. Slacken the two generator to bracket mounting
bolts.
3. Move the generator either towards or away from
the
engine to either slacken or tighten the belt.
4. Lock in the desired position by tightening the
ge:1erator
adjusting lever setscrew.
5.
Belt tension must be adjusted so that, without
undue pressure, the belt can be depressed '% in
(10 mm) with the thumb at the centre of the
longest free length (see Fig. M 1).
6. If the tension is correct tighten the two generator
to bracket mounting bolts.
NOTE: When a new belt is fitted,
it is advisable to
recheck the adjustment after only a comparatively
short running period. This is to allow for the initial
stretch which is common to new belts, once this
initial
stretch has taken place the belt may be
checked in accordance with Periodical Attentions.
SECTION M
Cooling System
To Remove the Fan Belt
1. Slacken the generator adjusting lever setscrew.
2. Slacken the generator to bracket mounting bolts.
3. Pivot the generator towards the cylinder block.
4. Turn the engine slowly by hand and work the fan
belt off the water pump pulley.
5. The belt can now be lifted from the generator and
crankshaft pulleys and removed from the engine.
6. Examine the belt for signs of fraying or cracks in
the
rubber and renew if necessary.
To Refit the Fan Belt
Refitting the belt is just a reversal of the removal
operation.
Adjust the belt tension as previously
detailed under the heading "To Adjust the Fan
8elt".
If a new belt ha'. been fitt0d refer to the note given
after the details on fan belt adjustment.
WATER PUMP
General
Two different types of pump are used, depending upon
the application. In one type of pump the impeller shaft
is
supported by two separate bearings, as shown in
Fig. M.3 and in
the other the bearings are combined
with the shaft to form one assembly, as shown in Fig.
M.4. The lastest
pumps of both types incorporate a
stationary seal that registers on a ceramic counterface
revolving with the impeller. Earlier pumps incorporate
a revolving seal that registers on a stationary counter-
face fitled in an insert fixed to the pump body, as
shown in Fig. M.5. In earlier pumps to the type shown
in Fig. M.5,
the seal registers directly on to the insert.
To Remove the Water Pump
1. Tap back the locking tabs, remove the fan securing
setscrews and remove the fan (and adaptor where
fitted) .
2. Remove the fan belt as previously detailed.
3. Unscrew the four setscrews securing the water
pump and back plate to the cylinder block.
4. Remove the water pump and backplate.