does any one know where the thermostat is located in the audi 100s.

 

Reg, I'm assuming its a 2.8L 12V engine. The thermo is under a housing buried in the front end of the engine under the timing belt covers. I would not tackle this job without a Bentley CD manual or some other service like like ALLDATA. Audis are great cars mechanically, but do require special tools and procedures. You can get your self into BIG hot water very quickly.

What ever you do, do not remove the timing belt if you try and remove the thermo housing unless you have the special tools to maintain the timing positions of the cams and crank. The housing can be removed ( wiht a lot of fidgeting) with disturbing the timing.

I bigger question is why do you think you need to remove the thermo? Are you sure this is your trouble?