mark944turbo

My car will overheat if i let it idle for 15-20 minutes, but then if i rev the engine up it will cool down immediately. This happens before and after the t-stat has opened. Since the waterpump is run off friction from the timing belt, could the problem be that it is too loose and only the high rpms provide enough force? What else could this be?

Tom M'Guinn

Most likely this is air trapped in the system -- very common on these cars. Air pockets prevent the water from circulating until you rev it. Less likely, but possible, is that your fans are not operating as they should. Clark's Garage website has a pretty complete diagnostic for cooling issues. BTW, if you are not sure whether your belts are slipping, it's probably time to check them.

jim944s2

there's a lower temerature thermo-switch for the fans that's a nice upgrade for about $20, I think the one I had turned on about 20deg cooler than stock. pretty easy to change too (contary to some manuals you don't have to remove any fans). I got mine from performance, but that was 6 years ago.

eugene

Mark.

I have had the same experience in the past. It was a lose timing belt.

It was slipping over the water pump pulley . Check it out.


Eugene.

mark944turbo

Thanks guys, ill re-bleed the system and see if that works, if not, time for a timing belt retention!