Wait until the engine is cold before starting this procedure. Do not allow antifreeze to come in contact with your skin, or with the painted surfaces of the vehicle. Rinse off spills immediately with plenty of water. Never leave antifreeze lying around in an open container, or in a puddle in the driveway or garage floor. Children and pets are attracted by its sweet smell, but antifreeze is fatal if ingested. Refer to the ‘Antifreeze mixture’ sub-Section below before proceeding.
Cooling system draining
To drain the cooling system, first cover the expansion tank cap with a wad of rag, and slowly turn the cap anti-clockwise to relieve the pressure in the cooling system (a hissing sound will normally be heard). Wait until any pressure remaining in the system is released, then continue to turn the cap until it can be removed.
Position a suitable container beneath the radiator. Open the drain plug access cover in the engine undershield (where fitted), then unscrew the drain plug and allow the coolant to drain into the container
. Discard the drain plug sealing washer, a new one must be fitted.
Rotate the drain plug access cover in the undershield anti-clockwise . . .
. . . then unscrew the drain plug (arrowed)
Occasionally it may be necessary to fully drain the cooling system. Remove the alternator, then slacken and remove the coolant drain plug from the left-hand side of the cylinder block, and allow any residual coolant to drain from the block. When the flow of coolant has stopped, wipe clean the threads of the drain plug and block. Where the plug was fitted with a sealing washer, fit a new sealing washer. Where no washer was fitted, apply a smear of suitable sealant to the drain plug threads. Refit the drain plug to the block, and tighten it securely.
If the coolant has been drained for a reason other than renewal, then provided it is clean and less than two years old, it can be re-used.
Cooling system flushing
If coolant renewal has been neglected, or if the antifreeze mixture has become diluted, then in time, the cooling system may gradually lose efficiency, as the coolant passages become restricted due to rust, scale deposits, and other sediment. The cooling system efficiency can be restored by flushing the system clean.
The radiator should be flushed independently of the engine, to avoid unnecessary contamination.
To flush the radiator, disconnect the top hose at the radiator, then insert a garden hose into the radiator top inlet. Direct a flow of clean water through the radiator, and continue flushing until clean water emerges from the radiator bottom outlet (the bottom radiator hose should have been disconnected to drain the system). If after a reasonable period, the water still does not run clear, the radiator can be flushed with a good proprietary cleaning agent. It is important that the cleaning agent manufacturer’s instructions are followed carefully. If the contamination is particularly bad, insert the hose in the radiator bottom outlet, and flush the radiator in reverse (‘reverse-flushing’).
Remove the thermostat.
With the radiator top hose disconnected from the radiator, insert a hose into the thermostat hose. Direct a clean flow of water through the engine, and continue flushing until clean water emerges from the radiator top hose.
On completion of flushing, refit the thermostat, and reconnect the hoses.
Cooling system filling
Before attempting to fill the cooling system, make sure that all hoses and clips are in good condition, and that the clips are tight. Note that an antifreeze mixture must be used all year round, to prevent corrosion of the alloy engine components.
||Ethylene glycol based antifreeze with OATS corrosion inhibitors
Slacken the bleed screw in the radiator top hose
Undo the bleed screw in the top hose
Release the upper bleed hose from the battery box, then remove the coolant expansion tank from the mounting bracket, and lift it approximately 20 cm.
Fill the system by slowly pouring the coolant into the expansion tank to prevent airlocks from forming.
If the coolant is being renewed, begin by pouring in a couple of litres of water, followed by the correct quantity of antifreeze, then top-up with more water.
When air-free coolant emerges, tighten the bleed screw in the radiator top hose.
Top-up the expansion tank to the correct level, then refit the expansion tank cap.
Refit the expansion tank to its mounting bracket, and clip the bleed hose into place.
Start the engine, run it until it reaches normal operating temperature, then stop the engine and allow it to cool.
Check for leaks, particularly around disturbed components. Check the coolant level in the expansion tank, and top-up if necessary. Note that the system must be cold before an accurate level is indicated in the expansion tank. If the expansion tank cap is removed while the engine is still warm, cover the cap with a thick cloth. Unscrew the cap slowly, to gradually relieve the system pressure (a hissing sound will normally be heard). Wait until any pressure remaining in the system is released, then continue to turn the cap until it can be removed.
Always use an ethylene-glycol based antifreeze with OAT (Organic Acid Technology) corrosion inhibitors.
Do not mix this with any other type of antifreeze.
Before adding antifreeze, the cooling system should be completely drained, preferably flushed, and all hoses and clips checked for condition and security.
After filling with antifreeze, a label should be attached to the radiator or expansion tank, stating the type and concentration of antifreeze used, and the date installed. Any subsequent topping-up should be made with the same type and concentration of antifreeze.
Do not use engine antifreeze in the windscreen/tailgate washer system, as it will cause damage to the vehicle paintwork. A screenwash should be added to the washer system, in the quantities recommended on the bottle.