View Full Version : Overheating issue.... Cant figure this one out

09-03-2009, 12:51 PM
Hello all, I've looked throughout the threads and various resources online and have no idea on where to go to get an answer. You guys seem the most knowledgeable and I have been able to pick up many pointers from audiworld so I figure this would be my best bet at finding an answer. Here is my detailed situation.

Bought a used 2001 A4 1.8t FWD. Looks like the previous owner had made a few mods to it and now, I guess I am left in the dark to figuring out why the car is overheating. Here is what I have checked and what I have done, hopefully someone can tell me what I need to do or what I did to make this happen.

Heres what happens:

Got the car about a week ago, have since put about 200 miles on it, was fine at first but now it seems as though at idle the car overheats, it goes over the midway point on the gage when I am moving, but just barely over the line. The ram air seems to keep the engine cool enough when moving and it's not like the temp spikes up in seconds but a few minutes at a light makes the temp go up a notch.

Both fans kick on when they are supposed to (so i assume it's not the t-stat), coolant levels are fine with no leaks in the tank or hoses, ac comes out cold...

Could it be my water pump? Is there a way to check that out without ripping the frontend off and getting into the nitty gritty?

Here's whats been done:

Seems like the previous owner had a manual turbo controller setup, cant really tell what the setting is at as I haven't set it up with a boost gage or taken it to get checked, could this be doing it? Also, I had put in the lucas gas treatment stuff as the mechanic that I talked to recommended since it was sitting for a couple months before I got it, could this be doing it? Also, I bought some of the Advance Auto Coolant 50/50 and put in as the coolant levels were low.... could this be doing it?
Also, it has an intake system that looks to be a K&M, I replaced the filter on it for a new cone filter and replaced the other filter (not sure what it was, but it was right next to the intake filter) as the old ones were really dirty. I did replace them with the right size filters, identical to the ones it had in. Could the filter change be causing the overheat?

I have gotten some really strong suggestions to include coolant, thermostat and water pump. I feel as though the fans turning on cancel out the thermostat, the coolant (as long as what i used isnt bad) shouldn't be the issue because there is no leaks and although it goes down a very very small amount it doesnt go down fast enough for the car to overheat before i notice it.

It seems the engine gets really hot, even just by standing in front of the hood, even for a turbo. Can it be that the turbo boost is set to a psi that is too high? If so, what is the recommended level?

Any suggestions or recommendations greatly appreciated and welcomed.

Also, I can take pictures if need be.

09-03-2009, 01:10 PM
Ill give you my two cents from one audi owner to another.

First and foremost, is the TB (timing belt) and all accessories been changed? You failed to mention mileage and maintenance done.

As for the coolant, the autozone stuff isnt good. Use the pink Audi/VW G12 stuff only. If not you will eat through your pump.

Since you say, it only happens when you standing/idling. Also your car warms up and stays warm when your driving around. I would say your T-stat is fine. Why its heating up when your standing could be a few things. Is you fan clutch working? It *could* be your water pump, but leave that for the last step. How does your coolant look? Is it dirty and cloudy or nice and clean?

As for the electrical fans, they only come on when needed. Ones for the AC and the other helps out the mechanical fan when your sitting.

Your air filter and boost level should not have any effects on your coolant temp.

Go out and flush your coolant. Put G12 in it and see what happens. Make sure your all your fans are working. Especially the mechanical one. Then go from there.

09-03-2009, 01:37 PM
Thanks for the reply. Sorry for not mentioning the maintenance and what not. The car has 133,xxx, so I am expecting to have to do SOME repairs. I was able pull a carfax on it and all the recommended maintenance looks like it has been done up until 111,xxx miles. Unfortunately, this doesnt tell me if the T-belt has been changed or anything else.

Both fans do come on when they are supposed to, 1st one comes on when I startup the car, the other one comes on when gauge hits midpoint or when I turn on the a/c.

BTW, the car seems to go just over midpoint on the temp gauge when Im driving, so it's "technically" not just while idleing. It's just not anything crazy, just a little bit over the mid.

Could the Lucas stuff make it overheat though, doesn't that stuff make it so that the particles come out of the gas lines?

09-03-2009, 01:54 PM
Perform a complete coolant fluid flush with G12 and see what happens after that. You want to get that Autozone stuff out of there anyways. Better to top off with distilled water than coolant not meant for our cars.

Clicky Click (http://www.audizine.com/forum/showthread.php?t=190397)

Seal 6
09-03-2009, 07:10 PM
what is a good normal operating temp and oil temp then? i'm usually a smidge below half way on the engine temp

09-03-2009, 07:38 PM
Engine oil temp should be ~210-15*F. I don't know about coolant temp though.

09-03-2009, 07:48 PM
plugged air filters WILL have an affect on overheating, altho not at idle. to check if the water pump is working, find a low pressure gauge (0-30 psi) and hook it up to the water pump bypass hose ( the small hose on the coolant reservoir) and rev it a little, pressure should be around 10 psi thats the quickest way to see if the oumo is working.

09-03-2009, 07:56 PM
Coolant temp should be 90c.

I'd check vag-com and see what the ECU is reading for the temperature. The coolant temp sensors have 2 independent circuits - 1 for the ECU, and 1 for the guage - and are known to fail. I'd check the other circuit (ECU) to make sure it is actually overheating before I go on a wild goose chase for a non-existant overheating problem. That is, unless there is other evidence that it is actually overheating (i.e. electric cooling fan kicks on after idling for a bit and doesn't shut off as temp guage rises).

Seal 6
09-03-2009, 08:39 PM
90c is where on the gauge? it's tick marked, but not numbered @_@

09-03-2009, 08:56 PM
I'm pretty sure the guage on the dash has a bit of "slop" in the middle. 90c is exactly in the center. But, I believe any temp from around 85-95c will read exactly in the middle as well. The reason is so the driver doesn't worry as the coolant temp fluctuates slightly, as it does normally.

09-03-2009, 09:22 PM
Check out this thread on coolant mixing.


Mixing the original G12 or G12+ (assuming that was in the car when you bought it) with standard antifreeze will cause the coolant to gum up and can clog the system.

10-03-2009, 10:54 PM
mine stays cool almost all the time,on a hot day with ac running it gets to standard operating temp of 90(half way). is this normal?? i drove about 200 highway miles today and it was barely above the C the whole time

10-04-2009, 10:20 AM
Could it be my water pump?

Is there a way to check that out without ripping the frontend off and getting into the nitty gritty?

Yes it could.

Yes, and no. Either method will get messy.

I hate to be the bearer of bad news, but if you don't want to run G12/G12+(pricey) you can run the GM Dex-Cool. As much as I hate the stuff, it mixes with G12 decent, and has more protection than the other cheap stuff that's available at the red-neck stores.
That being said, I stand by and love Toyota Red coolant. I will run it in anything I own, for as long as it's available. You can get the Toyota Pink ("extra long life") if you want, but it's more expensive.
... feel free to hate me, but that coolant is the bomb.

Like stated above, make sure your T-Belt has been changed. If it hasn't, do the whole shebang, TBelt, roller, tensioner, T-Stat, waterpump, etc.

While you're driving, the coolant temp gauge in the cluster should be about in the middle. Some read a tick high, some a tick low. I got lucky and mine was dead nuts in the middle.

One more thing to check, since it's had more than one type of coolant run through it, flush the shit out of your radiator. It could be clogged or clogging.
Also, make sure there aren't any coolant bubbles/pockets trapped in the heater-core. Have you tried the heater? If it doesn't work worth a shit, flush it, and bleed the air out of it.