ABY running hot, help,advice and info needed!

[psiconauta911]

Hi all,

Since the last service my ABY has been running hot!

At speeds above 70Kph it´s fine around 90ºC (since lots of air passes through the radiators) but whenever around town it goes till the 3rd dash above the 90ºC mark on the temp gauge until the the fan starts at high speed and brings it down to the 2nd dash then stops and the cycle repeats itself keeping the engine running hot.
If I catch some traffic or a steep hill the same happens.
If I turn the A/C on the fan starts in the lowest speed but the above happens also.

This begin to happen after the last service when the belt and water pump where changed, Audi also changed the sensor on the water manifold! after this they changed the thermostat and the temperature sensor in the main radiator (radiator is new) that comands the fan but the old ones where fine as it didn´t solve the problem(or the new ones are faulty!).

The eletrician tested the fan through the main radiator sensor plug and it worked on low and high speed.

As the guys at the Audi dealer weren´t able to fix this after the last service I would like to be armed with info/advice to try and help them!

I belive that the reason for this is that the fan isn´t turning on on the lowest speed as the temperature rises to near the first dash after 90ºC letting the temperature rise till the high speed is activated!

By the way what is the temperatures (in celsius) that activate the low and the High speed of the fan?

Thank you all in advance for the help, advice and info.

[UrS4boy]

Thermostat info

Thermostat info:

http://forums.quattroworld.com/s4s6/msgs/21881.phtml

[psiconauta911]

Thank you Dave,

So 95ºC low speed and 105ºC high speed, I thought it was something like 94 and 102ºC and that is close because in the ABY temp gauge as 90 and than 8 dashs before 120.

[UrS4boy]

So 95ºC low speed and 105ºC high speed, I thought it was something like 94 and 102ºC and that is close because in the ABY temp gauge as 90 and than 8 dashs before 120.

I never said 95 and 105. The marks that I made on that photo are pretty much 94 and 102. I got the info from an Audi source of some form (can't remember it now).

[psiconauta911]

Ok sorry, let´s assume it´s around 95 for low speed and just pass 100 for high speed.

[mike74]

These things are a b!tch to bleed properly. I'd be inclined to have a good feel around the coolant pipes, listening for air bubbles as I go round squeezing them. I took several attempts at mine after replacing the after run pump before it was bled properly.

[psiconauta911]

Thank you Mike,
I´ve thought of that to but in 15.000km and no leaks it must be bleed by now.
The thing that puzzles me it´s the fan not working in low speed when the coolant reaches 94 or 95ºC but works with the A/C on?

[UrS4boy]

The thing that puzzles me it´s the fan not working in low speed when the coolant reaches 94 or 95ºC but works with the A/C on?

This might help:

[Error404]

There are 3 rad speeds on the S2.

Stage 1 - with AC on or after-run pump active
Stage 2 - primary cooling kicking in just above 90deg
Stage 3 - secondary (emergency) cooling kicking in around 100deg

So your Stage 2 sounds like it's not working. This is controlled by a relay in the fuse board

I would check your rad is not partially blocked.
HTH

[psiconauta911]

There are 3 rad speeds on the S2.

Stage 1 - with AC on or after-run pump active
Stage 2 - primary cooling kicking in just above 90deg
Stage 3 - secondary (emergency) cooling kicking in around 100deg

So your Stage 2 sounds like it's not working. This is controlled by a relay in the fuse board

I would check your rad is not partially blocked.
HTH

Thanks for the info, didn´t know about the 3 stages!

Hope the rad isn´t blocked, was bought and instaled at the dealer and always with g12 but I´ll ask them t check it out.

[UrS4boy]

There are 3 rad speeds on the S2.

Stage 1 - with AC on or after-run pump active
Stage 2 - primary cooling kicking in just above 90deg
Stage 3 - secondary (emergency) cooling kicking in around 100deg

So your Stage 2 sounds like it's not working. This is controlled by a relay in the fuse board

Not that I don't think it is possible to have 3 speeds/stages, I am now going to have to check the various wiring diagrams to confirm/deny that. I think that there are 2 paths to the low speed and one to the full speed, relays 1, 2 and 3 in an UrS and similar in an S2/RS2.

[Error404]

You don't need to. I can tell you it is a fact

[psiconauta911]

I´ll check my relays in the morning! By the way in the first post I said the eletrician checked the speeds of the fan via the plug of the sensor in the radiator and both speeds worked shouldn´t this mean that the relays are ok?

[UrS4boy]

You don't need to. I can tell you it is a fact

Not saying that it isn't. I just don't believe it until I see it and internalize it myself. Then *maybe* I will believe.

Maybe.

(I don't even believe myself most days).