A4 having problems getting it up

[AndyMac]

Don't know if anyone else has had this problem, but my '97 A4 2.8 Quattro no longer gets up to the 90 degree temp (12 oclock position) on water temp, and the oil temp is down as well, even after a long journey. It seems to top out at about 75 degrees and has been like this for a while, so it's not just the cold weather.

I've had my dealer check it out and they say the thermostat is working fine, and maybe the fans are stuck on, but I haven't noticed them on at all unless I'm stuck in traffic, when the temp does go up to the correct level.
Anyone got any ideas, cause I don't want to damage the engine, by thrashing it when it's not at optimum temperature?

 

[moschino]

There might be a few more checks you could do before paying for the stat to be replaced.
As far as I can remember, the temp guage gets its reading from the engine block sensor not the rad. So even if the fans are stuck on the temp should reach 90 degrees or just under and stay there. There is a sensor on the rad itself that controls the fan relay.
I would suggest the best way to prove that the stat is faulty/stuck open, would be to start the engine and leave it to run. Lucky for you that you have a petrol engine as my TDi takes 10 Mins to reach the correct temp!
With any luck you will have access to the rad pipes. There should be 2 big pipes, flow and return. Feel the pipes, if they both get hot before the temp guage reaches close to the mid position then the stat is stuck open allowing coolant to flow through the rad.
This check worked on the Astra. I am in no way comparing your wonderful vehicle to a clapped out Vauxhall!! /ubbthreads/images/graemlins/smile.gif

Have a good Christmas.

Jim

 

[AndyMac]

Had the old girl checked over again and they found a faulty temp sender for the ECU, but didn't cure the problem, although car seems to be quicker. Had to rebook it in for the thermostat as it is a 3 hour job (difficult to get to). £200 later and problem solved, and again the car seems to be more responsive. Can't be just psychological as I wasn't expecting any performance change.
Don't know if the ECU holds back until engine has reached full temp?
Anyway good to see the reassuring 90 degrees on the motorway again.

 

[Patrick]

It's not unknown for the ECU to have some trick maps. The 20V Fiat Coupe holds back the boost pressure in 1st gear to stop the car spinning.

I heard that Audi ECUs monitor the outside temp to give as near constant engine performance. But I'm not sure about the source of this.

 

[jdp1962]

Andymac, did this new sender & thermostat fix the oil temperature reading as well, or is that still down? I've never been sure what the right oil temp reading should be on mine.

 

[AndyMac]

Yep, oil's back to normal as well, about 100 degrees.
It was wallowing in the 80's before, very worrying.