1.8T A3 Thermostat Problem?

[Greendubber]

I have a 2000 A3 1.8T Sport and it seems there's a problem. Driving home from work tonight I noticed halfway back that the temp needle was sat at its lowest point when normally it should be at the vertical. I'm guessing that its the thermostat thats kippered, the cars done 55K miles and I've heard its a common problem on them.

I'll get hold of a replacement but how easy are they to change and are there any quick checks I can do prior to buying to see if the 'stat is at fault?.

Any help/tips will be much appreciated.

[singlecoil]

I've got a 1999 A3 1.8t that I'm about to start taking to pieces, and an Audi workshop manual for it. I had a look at the thermostat figures
Which I have copied and pasted here.

Checking thermostat
l Thermostat removed.
– Heat up the thermostat in a tub of water.

Starts to open Fully open Opening travel
approx. 87 °C approx. 102 °C 1) at least 8 mm



Getting at the thermostat is not going to be as easy as it is on a BMC 'A' series engine!

HTH

Edited by singlecoil on Monday 2nd June 17:52

[Greendubber]

Yeah, I picked up a workshop manual this arvo and had a look.

I took the engine covers off and had a look at the stat and where it is etc, checked EVERY single electrical connection to anything remotely cooling system related and whilst its better, its not as it should be.

Sometimes it works, sometimes it doesnt. The fans are kicking in and the fact the guage does show the temp makes me think the thermostat is OK and its wiring related.

[JKY]

One common problem with 1.8T engines of that age is that the water pump impeller is plastic and breaks up. This is first noticable by fluctuating temp readings - in severe cases it can seize the pump and....well you can imagine the rest.
However if yours is dropping right off then it is more likely a sensor fault. Keep an eye on it though and change that pump anyhow when you get the cambelt done next.

[Greendubber]

JKY said:

One common problem with 1.8T engines of that age is that the water pump impeller is plastic and breaks up. This is first noticable by fluctuating temp readings - in severe cases it can seize the pump and....well you can imagine the rest.
However if yours is dropping right off then it is more likely a sensor fault. Keep an eye on it though and change that pump anyhow when you get the cambelt done next.

There are a few senders in the system etc so I'm going to get them changed and see whats what afterwards.

Cheers for the heads up on the water pump, although it was changed about 10K miles ago so fingers crossed its not that!.

[Colonial]

I have an S3 and just replaced the temp sender/sensor

Dirt cheap part and dead easy fix. Solved the problem without much expense

[Greendubber]

Colonial said:

I have an S3 and just replaced the temp sender/sensor

Dirt cheap part and dead easy fix. Solved the problem without much expense

Ah cool. I had a look and took the old one out the other day to make sure all the connections were OK, problem still there. Can get the part from GSF for about a tenner so I'll be sourcing one this arvo and swapping it over later on.

Cheers!

[Kentish]

If you have the digital climate control you can check your actual engine temp (the dash is just a weighted guide usually set at 90 when it is within +/- 10 of 90 degrees.

Press the UP "screen" button and then the "Recirc" button and the display should brighten and read "1c" use the up/down temp control to scroll to 49c then press the Recirc button and it'll give the true temp reading - it it is low (below approx 89 when on a run) it is likely that your stat is sticking open (a common prob on a 1.8T).

Changing the stat is a bit fiddly but is still a DIY job.

[Greendubber]

Kentish said:

If you have the digital climate control you can check your actual engine temp (the dash is just a weighted guide usually set at 90 when it is within +/- 10 of 90 degrees.

Press the UP "screen" button and then the "Recirc" button and the display should brighten and read "1c" use the up/down temp control to scroll to 49c then press the Recirc button and it'll give the true temp reading - it it is low (below approx 89 when on a run) it is likely that your stat is sticking open (a common prob on a 1.8T).

Changing the stat is a bit fiddly but is still a DIY job.

Ah lovely, I'll give that a go and see whats what. I'll take it out for a spin to get it nice and warm and then see what it says.

Cheers

[Greendubber]

All sorted now, seems the coolant sensor on the pipe by the thermostat was to blame. Quick call to GSF, ten pounds later and 15 minutes fitting and its all sorted.

Cheers for the tips, couldnt get the AC to give me the stat readout but the fans are kicking in etc when its hot and the expansion tank has water running through it so no nasty water pump problems.