High Running Temperature

[simonkd]

Hi All

What are the most common causes of the engine suddenly running 10deg hotter than normal?
My usual running temp is between 80 & 90 deg during this cold weather, but today during a 20 mile round town trip averaging 40 mph the temp was betwween 90 and 100+. My fans came on a couple of times aswell even though I wasn't stuck in any traffic jams. Water level is normal in the expansion tank.

Your thoughts are appreciated
Regards
Simon.

[jensena]

Its possible you have an air lock, get the car warm and bleed it with the 2 bleed valves on the top of each of the coolant rails alongside each bank.

[ridds]

Don't rely on the dash temp guage. Mine over-reads by 5°C. Ran my car with the laptop connected and compared them both to be sure.

[Wilder]

I got told by the service dept boys at the factory that The fans kick in at 94 & 96 degrees C, so the temp gauge is probably correct, though it can be out by up to 8 degrees C as capilliary guages are notoriously crap re their accuracy.
The sensor seems ok as the fans start up, so Id go with the airlock theory.

[DaveR]

Having lost coolant via not-the-best hoseclip was the cause of mine suddenly running warmer lately. Always nice when the remedy is a £1.99 DIY job.