cooling and heater circuit diagram

[dhla40]

Does anyone have a diagram of the cooling and heater circuit of a S2? I have a leaking heater matrix and during investigation I noticed that the hose from the top of the engine goes to the valve at the bottom of the heater and the hose from the top of the heater goes to the bottom of the radiator.  I am concerned that this will cause an airlock in the heater during refill, can anyone confirm the correct orientation of the hoses.

Sean

[Jaydub]

Sean, that is correct so that the Hot incoming water from the cylinder head enters the bottom of the matrix and exits from the top thereby pushing any potential air locks out with it and then returns to the inlet of the water pump.

[nistri]

plus the fact that, in the engine bay, there should be a tap with a bleed screw in the return hose from the heater to get any air out, rarely necessary if the system is refilled slowly, Andrea

[dhla40]

OK thanks for confirmation, will take care on refill.

Sean

[lancialulu]

On S2 there was a bleed valve in the return to rad pipe near the engine cross member. I have this on my car. I have never had to use it. The system seems to fill completely without air locks when refilling.

The bleed valve is made from brittle plastic so can break.