944 turbo overheating help please

[polar57]

First post so please be gentle...

Just need a bit of tech advice about overheating problem 944 T 1990

Symptoms: After approx 1 hour of driving noticed temp rising slowly, steady driving at 60ish.
Stopped to check under bonnet and fans ok, water low, top up with 1/4 L.
Continued driving a couple of miles temp rising fast, stop again needs 3/4 L worried!

Call AA, they decide unable to fix, car gets towed home. AA think it’s the water pump as water only leaks when the engine is running , he pressurised the system, engine off and it was ok.

Any advice much appreciated, I have it booked in with a local mech, but could do without towing for 25 miles (Aberdeen) if its something simple,

Thanks.

[S99]

Any white 'smoke' coming out of the exhaust?

Could be a head gasket?

[tr7v8]

Smells of a jammed thermostat, unfortunately a pain to get out.
Other option is blocked rad, or possibly the water pump.
Pump is driven by cam belt so is the front end noisy?

[polar57]

Thanks for the replies so far.

I have just tried it from cold, it needed 1 1/2 L to get the level back to max.

On cold start there does seem to be white smoke, but this could be normal?Can't really remember.
Initially It seems to run fine, no noises etc until it gets up to temp, ie thermostat open, then water flows quite fast from what looks like the botton of the radiator, not from the engine area itself.

Also there doesn't seem to be any movement of water in the expansion tank, but this could also be normal from cold, I switched it off when all the water started coming out.

Thanks again.