996TT Running cold

tykes · Dec 10, 2015

I have a 2002 996TT that I owned in Dubai and now have back in the UK. Whilst in Dubai the engine temp was always pointing straight up regardless of the outside temp and whether or not the aircon was on and the fans came on and off as required.

Since getting the car back here I find that it runs very cold rarely getting over 60 unless stationary and dropping back once on the move. I have changed the thermostat as a precaution although the old one seemed fine and was not stuck open.

What else would cause the engine to run cold? With the colder weather I am struggling to get any heat out of the heater.

The car is a tiptronic so has the additional radiator - I have read somewhere that there is a solenoid valve in the cooling circuit and that this might be the problem. Where is it and is it an easy fix?

Any suggestions?

Many thanks

Richard

Richard_Hamilton · Dec 10, 2015

The Tiptronic coolant valve is vacuum operated, and the problem is usually caused by the vacuum pipe becoming detached or splitting. The small vacuum pipe runs from the throttle body, down behind the alternator, to the valve (item 8) on the side of the transmission.

Gordon Attar · Dec 10, 2015

Sorry for stating the obvious have you had the coolant flushed and replaced with the reccommended UK solution as they use a very strong hot climate solution in the middle east to maintain the operating temperature down along with a beefed up cooling system. Make sure your specialist knows you have a UAE car as not all the parts will be the same.

tykes · Dec 11, 2015

Thanks for the replies.

Yes I have flushed the cooling system and refilled with UK stuff although in the UAE I always used Porsche coolant which I would assume is the same wherever you buy it.
I will check to see if the vacuum pipe is actually performing. If it is then I assume changing the valve is the next step. Is the normal position for the valve closed until the temp rises? Is there a temp sensor for this purpose or does the ECU control this valve?

Thanks

Richard_Hamilton · Dec 11, 2015

There is a solenoid valve, which is controlled by the ECU, which opens and closes the vacuum operated valve (item 8 in the diagram) to control the flow through the cooler (item 1). This valve is in the pipe (14 + 15) which runs to the throttle body. The solenoid valve is shown on the diagram, but isn't numbered. I think you will find your problem in the pipe or connections, but if not it could be the solenoid valve, the vacuum operated valve, or possibly the wiring to the ECU.