Water alone should not be used for filling a cooling sys- tem as it causes corrosion. A proprietary anti-freeze mix will not only prevent the coolant freezing, but contains add i- tives that discourage corrosion and the build-up of scale deposits.

Step 1. Check that all drain points are closed and that the hose clips are properly tight- ened. Set the heater control to hot’ or ensure that the heater water valve is open.

2. Dilute the anti-freeze with tap water or, better, clean rain- water in a watering-can, according to the protection required—see the manufactur- er’s instructions.

3. If there is an expansion reservoir, fill this one-third full, orto the level marked on the side. Where the cooling system has bleed valves, they should be fully opened.

4. On cars without bleed valves, pour the anti-freeze through the filler hole, pouring slowly to avoid airlocks. When the coolant level reaches the filler neck, leave the cap off, and run the engine at a fast idle speed. As the water pump cir- culates the coolant, air locks will be released at the filler hole. After about five minutes, stop the engine, top up the coolant, and refit the filler cap. Run it again until normal temp- erature is reached and check for leaks.

*4 On cars with bleed valves it may be necessary to clamp the circuits incorporating the val- ves, using a hose clip, in order to force out pockets of air from the heater and inlet manifold.

*5 The method Renault recom- mends for its 5 and 12 models is fairly typical. When the water reaches the top of the radiator filler neck, the return hose from the heater and the hose from the inlet manifold are clamped near the water pump. Renault makes special clamps for this purpose, but Girling brake- hbse clamps or two self-grip wrenches, applied with care, will do. Pack small pieces of hard board under the jaws to prevent them cutting the hoses.

*6. With the bleed screws open, run the engine at a fast idle speed. The level in the radiator will drop. Keep filling it until water flows from a bleed valve continuously without a trace of air. Close each bleed valve when this happens. Remove the clamps, top up the radiator, run the engine to normal temperature and check for leaks.