Draining and refilling the RV8 coolant system
Following a query raised on the V8 Bulletin Board, Peter Garton sets out the procedure he uses to drain and refill the coolant system on his RV8.. (Apr 12)

It must be emphasize right from the start that refilling the coolant in a 3.9 litre V8 engine with an RV8 is a job that can take several days. The reason for this is the series of air locks encountered by the amateur. The airlocks result in no heating or a loss of water level visible in the expansion tank! Patience and still more patience is required here. Thus we can commence by draining off the coolant. It is vital to remember the following steps:

1. Position the heater control to to the "hot" setting but note this alone can cause trouble if the heater valve cable connection is slipping resulting in the cable not levering the operating valve over to the hot position!!! Therefore it is wise to check that nothing is loose and the valve is really turning from left to right. This valve is located at the rear of the engine and is difficult to access easily.

2. Remove the filler plug located on the lefthand side of the engine - originally plastic or it may have been replaced by the better brass plug. The plastic ones are a problem and can easily be damaged thus the replacement by a brass one. Remove too the expansion tank cap!!

3. Slacken the clip of the bottom hose located at the bottom of the radiator and disconnect the hose. Assuming there is no reason to suspect the radiator is blocked or there are other problems, one can now start the reverse process and refill the cooling system.
4. Reconnect the bottom hose.

Fill SLOWLY, via the filler pipe, and watch the coolant level in the expansion tank.

6. It can happen that the filler pipe starts to overflow
prior to the coolant reaching the marking level on the expansion tank.

4. One now squeezes and releases the top hose and one can see the expansion level going up and down and there is usually a sound of gurgling and bubbling. Maybe the filler plug will also overflow and so replacing the cap temporarily eliminates this. Continue squeezing and then refill a bit more until no more air bubbling seem to be in the top hose area.

5. Refit the expansion tank cap and fill until no more water will go in without overflowing.


7. Start the engine and wait until the fans start to turn.

8. Wait to cool and recheck the levels. The level in the expansion tank will go up and down depending on whether the engine is hot or cold!!

9. Check the water level via the filler plug again and squeeze the hose several times when the engine has cooled down. This procedure can take several attempts.

10. Now is the time to check that the heater is actually working, which it should be, since the heater valve is still open.
Copyright reserved by the V8 Register - MG Car Club