Audi A2 FSI Overheating Sporadically

NickMellis

A2OC Donor
I have a 2003 A2 FSI. Milage is 127k. Over the past few months it has been overheating when the engine is under load i.e. when going up large hills. I stop for 5 mins and it is back to 90 degrees.

I have replaced the coolant and the coolant drum.

I have been told the thermostat is stuck open so that it takes the temp gage longer than normal to come up to 90 degrees. Garage has said there is not a need to replace it.

I got the timing belt changed last year just after I bought it. Would it be normal for garage to change water pump at same time?

I was thinking it could be one of the following four things:

New radiator needed;
New thermostat needed given the above problem;
New water-pump needed if it has not been replaced
Potentially a sensor issue?

All advice welcome.

Nick
 
I have a 2003 A2 FSI. Milage is 127k. Over the past few months it has been overheating when the engine is under load i.e. when going up large hills. I stop for 5 mins and it is back to 90 degrees.

I have replaced the coolant and the coolant drum.

I have been told the thermostat is stuck open so that it takes the temp gage longer than normal to come up to 90 degrees. Garage has said there is not a need to replace it.

I got the timing belt changed last year just after I bought it. Would it be normal for garage to change water pump at same time?

I was thinking it could be one of the following four things:

New radiator needed;
New thermostat needed given the above problem;
New water-pump needed if it has not been replaced
Potentially a sensor issue?

All advice welcome.

Nick
My first reaction is how a thermostat that's stuck open, can cause an engine to overheat!
Also, if you know/guess a thermostat is not functional, you'd replace it.
It is normal to replace the water pump when replacing the cam belt.
I'll have think, and come back to you, but my first thought is water pump or thermostat.
FSIs need mechanics who know what they are doing, yours may not ...
Mac.
 
My first reaction is how a thermostat that's stuck open, can cause an engine to overheat!
Also, if you know/guess a thermostat is not functional, you'd replace it.
It is normal to replace the water pump when replacing the cam belt.
I'll have think, and come back to you, but my first thought is water pump or thermostat.
FSIs need mechanics who know what they are doing, yours may not ...
Mac.
I think @A2Steve may have an FSI thermostat. Easier to change than a water pump.
Mac.
 
That is interesting. I go to Dialynx in Swindon. So far the mechanics have been great.

Will double check with the garage if the water pump was changed with cambelt.

I know they did a block test in the coolant tank, and no exhaust gasses were present so they have ruled out head gasket.

If it is the thermostat, I think I will insist on it being changed.

Thanks for your help Mac.
 
That is interesting. I go to Dialynx in Swindon. So far the mechanics have been great.

Will double check with the garage if the water pump was changed with cambelt.

I know they did a block test in the coolant tank, and no exhaust gasses were present so they have ruled out head gasket.

If it is the thermostat, I think I will insist on it being changed.

Thanks for your help Mac.
The FSI thermostat is a bit special (as indeed is the FSI), and quite a few pennies.
A pre-owned from @A2Steve would be much cheaper.
Mac.
Edit: A scan would be a good idea, there are three members near you who would do that for you.
 

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Correct me if I am wrong ( I am sure someone kindly will ), but I always thought the FSI thermostat was a hybrid. Conventional wax but also electronic. Normal use it is just the wax but high load the electronic part opens to increase the flow through the thermostat housing. IF I am correct then perhaps it it the electronic extra flow part that is either failed or intermittent.

I await my education / clarification.🤓
 
I would also check that your radiator fan is working at the higher speeds ( temp controlled ).
I think you can do this with VCDS. I'll check.
Correct me if I am wrong ( I am sure someone kindly will ), but I always thought the FSI thermostat was a hybrid. Conventional wax but also electronic. Normal use it is just the wax but high load the electronic part opens to increase the flow through the thermostat. IF I am correct then perhaps it it the electronic extra flow part that is either failed or intermittent.

I await my education / clarification.🤓
Yes, indeed it is. There's a heater resistor in the wax capsule, which opens it at a lower temperature (87C) when the engine is working hard. Controlled by the ECU.
Mac.
 
There is an absolutely terrific mechanical whizz kid at B&F Autos in West Hounslow. Knows his A2 and is well known on here. His name is Gary and I'm not connected, just a happy and delighted customer.

Really is vital with these to go to somebody who really does understand them.
 
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The FSI thermostat is a bit special (as indeed is the FSI), and quite a few pennies.
A pre-owned from @A2Steve would be much cheaper.
Mac.
Edit: A scan would be a good idea, there are three members near you who would do that for you.
Number 3 on the map seems near me in Wiltshire. Do we know who and where that is in Wiltshire?
 
I think you can do this with VCDS. I'll check.

Yes, indeed it is. There's a heater resistor in the wax capsule, which opens it at a lower temperature (87C) when the engine is working hard. Controlled by the ECU.
Mac.
Does anyone have a rough guess of the number of hours labour to change the thermostat?
 
Number 3 on the map seems near me in Wiltshire. Do we know who and where that is in Wiltshire?
Names here, approximate location too:
Mac.
Does anyone have a rough guess of the number of hours labour to change the thermostat?
Just a guess, I'd say 2 garage hours. Only use a genuine VAG thermostat, aftermarket thermostats of this (FSI) complexity will disappoint.
The mechanic needs to take great care to avoid damaging the plastic housing.
Mac.
 
Names here, approximate location too:
Mac.

Just a guess, I'd say 2 garage hours. Only use a genuine VAG thermostat, aftermarket thermostats of this (FSI) complexity will disappoint.
The mechanic needs to take great care to avoid damaging the plastic housing.
Mac.
Number 3 is @damadgeruk , Westbury Wilts. Click on the members ID, and, in most cases, there will be a location.

Bit late, but welcome to the A2OC! Oh ... hang on, you're not that new, sorry!

Mac.
 
Nick,

Very happy to help where I can. Not hugely familiar with the FSI but with information on here and the excellent guidance you have already can only give you the best options going forward.

Speak soon. Paul
 
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