How can i tell if the thermostat is bad in my 1993 audi 90cs?

I remember doing this years ago. Remove thermostat from the car and drop it into a pot and then pour boiling water over it. If it's good you will see it change shape as the bellows function. If this doesn't happen replace it. Just bear in mind that the Audi can't be driven without a thermostat, so if you have no other transport see if you can buy a replacement thermostat on a sale or return basis!

Are they blinking from the moment you start or only after it's overheating? Replacing the relay as well as addressing any other obvious stuff would be the first step. Check coolant level and condition, assure the pressure cap is good and there's no leaks.

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First of all check the fan fuse to c if it's ok if it is then replace your fan switch on the side of the radiator cause that tells the fan when to come and it's a common fault on most vw cars if all else fails u will need to test and c if the fan is still working,u can check that by either putting direct power to the fans wiring if it does work then change the thermostat

There are dozens of possibilities from as simple as a bad pressure cap or low coolant level to as bad as a cracked engine block. Knowing the conditions that cause the overheat would help diagnose, here's some basics--assuming the coolant is full. Only overheats at low speed is generally an airflow problem: fan not running because of a fuse, relay, temperature switch, or dead fan motor. Only overheats at high speed is generally a coolant flow problem: radiator is plugged up, faulty thermostat, water pump vanes damaged. Tell us anything you've checked, any recent repairs done, and the conditions under which it overheats.

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You need to replace the clutch slave.....Ii recently did mine, after the installation it was stuck too.......the way I fix it was I had a friend pumping the clutch by hand while I bleed it under the car, it took about 15-20 minutes before it got hard again.
Good luck!

Check cold start fuel injector.

94 audi 90cs hard start cold

Follow the upper and lower radiator hoses to the engine block (upper first). At the end of one of these hoses, there will be a "bubble" housing attached to block -- thermostat is under that.

Charlie

starters seem difficult, but can be accomplish relatively quickly. there friendly because you don't have to worry about belts and gaskets. My assumption here is that you know you need to replace the starter and you know where the starter is located.
first disconnect negative battery cable.
On the starter you will need to disconnect power and ground. then you can pull the bolts and remove the bad starter. Installation is reverse of course. Once installed and secure, always double check the gound connection. reconnect battery and off ya go. Time should 45ish minutes.

you need to take a multimeter to the wires on the motor and if voltage is going to the window motor then you have a bad window motor and it needs to be replaced. I hope that helps you out.