944 Turbo PumpProblems

This is switched on and off by relay G22. Fuse F7 is the fuse for the power feed. Check this first.

The pump runs under two conditions;
1) when the ingnition is switched off, the loss of power from the DME relay causes a timer circuit in the relay to run the pump for 30 seconds.
2) there is a temperature sensor that can cause the pump to run. This is the sender often discussed on here which some times wobbles on the top connector !

As stated, water is pumped back in to an inlet in the header port and can be clearly seen as turbulance in the lower left corner of the tank for 30 seconds when the engine stops.

You could also force the pump to run by pulling off the wire to the temperature sensor and shorting it to earth with the engine cold / not running.

As with all turbo cars, it is always good to idle the car for about a minute before switching off, longer if you have been caning it ! The reason for this is that when the engine is turned off, the oil supply is cut to the bearings on the turbo, while the shaft continues to rotate for up to 30 seconds as the turbo 'wheels' slow from 10's of thousands of RPM. This can cause the oil in the bearing to overheat and leave the shaft running without lubrication with the obvious long term effect ! This is also a reason why you should not 'blip' the throttle on a turbo car before turning the engine off ...

Hope this helps. Rick. rick.cannell@cubicomp.co.uk 944 Turbo - 1990 944 S - 1987 www.cannell.co.uk