Rolls Royce Corniche Workshop Manual 1989

The sealed cooling system comprises a pressurized expansion bottle. a radiator. and a pump. Also, various passages and pipes convey the coolant around the system (see fig. 12-11. A mixture containing equai amounts of approved coolant anti-freeze and water should be used in the system at at 1 times. The coolant mixture in the system should always be maintained at the correct level and this must be checked at the intervals specified in the Service Schedule Manual, TSD 4702.

The coolant level can be checked at the translucent expansion bottle. The correct level should be between the MAX and MIN marks onthe bottle. If a full checkis to be carried out refer to page L3-3. The cooling system is pressurized and the correct pressure is maintained by the expansion bottle pressure cap. Removal of the pressure cap while the engine and radiator are still hot require sextreme care. The coolant pump is situated at the front of the engine and is driven from the crankshaft by twin matched 'Vee' belts.

Coolant from the bottom of the radiator is pumped via transfer pipes and crankcase passages directly onto the outside of the 'wet' type enginecylinder liners and then into the cylinder heads. From the cylinder headsthe coolant travels along transfer pipes and then flows past the thermostat to the top of the radiator, Rolls-Royce Corniche Convertible Wiring Diagram 1978 - 1978, Rolls-Royce Corniche Workshop Manual 1989,Rolls-Royce Corniche 1989.

When the engine is cold the thermostat is closed. Therefore, the coolant by-passes the radiator matrix and is recirculated through the engine to reduce the warm-up period. Once normal operating temperature is attained, the thermostat opens and the coolant is directed to the radiator.

The temperature of the coolant is registered on the gauge situated on the facia. Whenever the ignition ison,a transmitter situated in the thermostat housing signals the coolant temperature to the gauge.

Coolant
The cooling system should contain a 50% mixture of an approved coolant anti-freezeand water. This mixturenot only provides frost protection down to a temperature of -37°C I-35"F), but it also prevents corrosionof the cooling passages. Referto the Service Schedule Manual, TSD 4702, to obtainthe specified service intervalsfor renewing the coolant,fitting a new thermostat,and reverse flushing the system. Except in an emergency, water must not be used to eitherfill or top-up the cooling system. If a situation does arise where water is used,the coolant mixture must be corrected as soon as possibie, ohe twise corrosion damage will occur to the engine cootant passages.

Cooladanti-freeze
The trade name of the coolant anti-freeze is fC1007i 400F {obtainableunder a Rolls-Royceand Bentley label) and should be used all year round. Do not mix IC1007/400For topup with any other brand of coolant/anti-freeze.

AML freeze concentration To check
If the strength of the coolant requires increasing. sufficient coolant should be drained from the radiator and replaced with undiluted anti-freeze. After wards runthe engine until normal operating temperature is attained andthe anti-freeze has become thoroughly mixedwith the coolant. Stop the engine and again check the concentration inthe expansion bottle. An acceptable levelof anti-freeze concentrationis between4 5% and 5596. Therefore, as a hydrometer may be inaccurate where readings above 40% are expected, it is recommended that a refractorneter (see fig. W-l) is used in the following manner.

1. Lift the plastic cover on the refractometer (tester) to expose both the measuring window and bottom of the ptastic cover.
2. Thoroughly clean both exposed surfaces with clean water and then wipe them dry with a clean soft cloth.
3. Carry out the usual workshop safety precautions.
4. Raise the bonnetand remove the expansion bottle cap.
5. Release the tip of the clear plastic tube from the tester and insefi it into the coolant inthe expansion bottle.
6. Pressand then release the bulb on the end of the plastic tube.This will draw a small quantity of coolant into the tube.
7. Withdraw the teste quipment and bend the endof the plastic tube a round the tester so that the tip of the tube can be inserted into the cover plate opening.
8. Pressthe bulb on the endof the plastictube and eject a few drops of coolant onto the measuring surface.
9. Point the tester to wards the light and look in to the eye piece.

Example
A tester reading of -29°C (-2VFl is equal to an antifreeze concentration of 43% and is out side the service limits. Follow the lineupwardsuntilthe angled line is reached, then trace the horizontal line to the scale on the right-handsize ofthe graphtofindthat 2 litres(3.5 Imppt, 4.2 US pt)of coolantshould be removedfrom a full system and replacedwith undilutedanti-freeze. Oncethe additional concentrated anti-freeze has mixedwith the existing coolant the percentage concentration will be 50%.