Audi 1988 5000 CS quattro overheats while idling ... any idea why?

I have an Audi 1988 5000 CS quattro that when I have the engine running, while in neutral, with the parking brake on, just minding my own business, the temp gauge will rise until the car is overheating.
It just started doing this ... any help would be appreciated.
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What are the symptoms of overheating? Does the fan run? Have you checked the thermostat? Flushed the system? Larry

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wrote:

When I leave mine in idle, it goes up to about 80 to 90 degree C, and then the fan comes on for a while. When left for long, the fan just goes on and off.
Without the fan, it doesn't have a chance to get rid of the heat, since there is no wind blowing through the radiator when it is standing.
Christoph
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Quisp Smith wrote:

Check the function of the thermoswitch which lives the the bottom corner of the radiator
These switches die, and then the electric fan won't come on, which results in the car overheating.
If you don't yet have a Bentley manual, buy one.
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Quisp, If the fan is coming on (check the fan using the procedures you can find at www.sjmautotechnik.com) - then it is possible that you have a blown head gasket or rad problems. I had one in my '87 5ktq - when the car was started from cold, the temp would rise to about 100C, then fall (presumably as the heater core is opened to the system and the colder coolant causes a net drop in temp), then it would rise to boilover. Result was: blown head gasket in area of Cylinder #5 (rearmost) - gasket replaced. Shortly thereafter, the rad blew up. Forensic analysis (= tore the *^*&% thing apart to see what was wrong) revealed a break in the gasket separating top (in) and bottom (out) - result was that coolant was bypassing the rad. Replaced the rad with a metal Modine rad, the gauge seldom breaks 100C now. If you've seriously overheated the car, then you might have a warped head ~ blown head gasket as the movement between the cast iron block and aluminum head would cause a leak. Any coolant in the oil/oil in the coolant/discolouring of the sparkplugs (whitish residue)? Cheers! Steve Sears 1987 Audi 5kTQ 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)

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