I have a 2000 Audi A4 with the 1.8T. I was driving and it started to overheat. i turned it off and the temp went down to the half way mark within 2 min of it being off. I then got it home and let it cool down all the way. I started it again and with it sitting there for over a half hour it went to the half way mark and that was it. Then I took it out for a ride and around 2500 RPMs the temp went back up. I put a new thermostat in it and it didn't help. Anyone have any ideas, it only heats up when the RPMs are over 2500.

Timing belt and water pump have around 20k miles on them.

Any help is great

Thanks

 

could be the coolant temp sensor, i've been putting off replacing one for a while now lol

 

how difficult are those to change?

 

not terribly involved, but problematic if you have normal human-sized hands. The CTS on the 1.8T is on the back of the cylinder head buried under a bunch of ****, so it can be a pain to get to. the sensor is pretty cheap, getting to it is the hard part. search here and audiDIY and see what you can find

 

I have had to deal with this part many times as my original coolant flange cracked on my and my remedy until i got a new was was removing and resealing it with black rtv silicone so coolant isn't gushing out like some stabbed my engine. Here is what I did to access this problematic area numerous times:

1)remove the plastic engine cover

2)remove the exhaust heat shield on the left side of the engine, its held down my 4 small 8mm bolts. This step is so you have clearance for you left hand to reach the area behind teh motor to your coolant flange, which is where your CTS is at.

3)remove the 6mm i believe allen bolts holding down the vent pipe coming from the PCV valve going around the back of the engine all the way to the right side, remove the clamp as well attaching this pipe to the PCV and remove. This step is to loosen this pipe, and its the biggest PITA specific to the area which you will be working on.

Now you may remove the wire connector and remove the hold down clip for the CTS and lift up, obviously do this when the engine is cold so you don't go and burn yourself and make yourself the perfect candidate for TwoFace for the next Batman movie

 

now also I noticed something that I can hear the water boiling in the car with the heat on. But when the temp goes to where the alarm goes off the air comes out cold again. Any ideas?

 

thats my exact problem with my a4. how did you end up fixing it?