SECTION 26                           COOLING SYSTEM                                           STAG

COOLING SYSTEM

General

The cooling system is pressurized, with an overflow bottle to effect a 'No Loss' system.  
System pressure release on filler cap at 13 lb./in
The principal components of the system are:

Radiator

Conveniently mounted by four bolts and easily removed.

Water pump

The impeller-type pump is mounted at the front end of the engine between banks and driven by a skew gear from the jackshaft.

To remove the water pump

1.	Remove the air cleaner and elbows.
2.	Disconnect carburettor controls.
3.	Remove carburettors.
4.	Drain coolant.
5.	Disconnect water hoses from water pump and thermostat housing.
6.	Remove inlet manifold.
7.	Remove three bolts and lift off water pump cover.
8.	Apply a spanner to the centre-bolt head, turn gently clockwise.  
	This may release the pump from the jackshaft skew gear; if not, it will remove the bolt which has a 
	left-hand thread. (Fig. 26.01)
9.	Where the bolt has been removed, screw the impact tool and adaptor (54235A/6, 4235A (3072) into the 
	threaded hole and remove pump.

Fitting pump

1.   	Check spigot bearing in cylinder block; renew if damaged. 
2.	Fit pump into cylinder block, ensuring that the gears of pump and jackshaft mesh correctly and that
	the pump is fully seated.

NOTE:	By turning the centre bolt gently in an anti-clockwise direction the pump will normally seat 
	correctly.

CAUTION:The use of impact to seat the pump will damage the graphite seal.

3.	Ensure that the gasket faces of housing and cylinder block are clean.
4.	Fit housing without gaskets; fit the three bolts and tighten evenly to finger tight.
5.	Ensure that the housing is level by checking gap between housing and cylinder block 
	at three points between the bolts. (Fig. 26.02)
6.	Measure gap between cylinder block and water pump housing.
7.	Select water pump gaskets to equal the gap noted in (6) above +0.010 to 0.020 in. 
	(0.25 to 0.5 mm.), which is the required running clearance between centre-bolt and 
	lug in pump housing.
8.	Remove pump housing.
9.	Fit gaskets and pump housing, securing with three bolts and washers.
10.	Fit inlet manifold.
11.	Connect water hoses.
12.	Refill with coolant.
13.	Fit carburettors.
14.	Connect carburettor controls.
15.	Fit air cleaners and elbows.

Fan and Torquatrol unit

A 13-bladed 16.5 in. plastic fan driven via a torque limiting drive assists the engine cooling.  The torque limiting device (Fig. 26.03) 
operates on a principle of a shear fluid coupling in which a driving plate anchored to the crankshaft, transmits drive to the driven 
plate via a film of silicone fluid.  The driven plate is bolted to the fan which, at the maximum efficient fan speed, will apply sufficient
torque to slip the drive.  Thus a maximum fan speed of approximately 2,500 r.p.m. is maintained.
No servicing of the unit is required.

To remove

1.Remove radiator.
2.Remove centre-bolt into crankshaft pulley.
3.Lift out fan and Torquatrol unit.
4.Separate by removing the four nuts attaching the fan to the unit.  Refit by reversing the above procedure.

Thermostat
The thermostat housing is secured to the inlet manifold directly above the water pump.

To remove (Fig. 26.04)

1.Drain off part of the coolant.
2.Disconnect water hose from thermostat housing.
3.Remove the two bolts in-housing.
4.Remove the housing.
5.Lift out thermostat.

Refit by reversing above procedure, clean gasket faces, use a new gasket coated with jointing compound.  

Thermostat opens at 82 deg C.