OK, I'll start from the beginning..About 2 weeks ago(95 outside)I was driving, of course w/ the ac on, and the car started overheating. I noticed a hose was leaking which seemed to be running to the oil cooler?, Right above oil filter. I replaced the hose and it seemed to be ok, even w/ac on. Yesterday my oil temp warning came on and the coolant temp went way up, because of another hose that broke, leaking all the coolant out(also had AC on). I just had my local mechanic replace the hose for me since I couldnt get to it(was located above passengers side turbo intercooler hose). I picked up the car, ran at idle w ac on for about 15 min and seemed fine. All fans were working. I drove the car with ac on for about 25 min and the oil warning came on and coolant temp went 2 notches past halfway mark. I shut ac off and everything seemed fine. Any help would be appreciated...I just got laid off from work for about 3 weeks now, and I cant afford to take to dealer..could air have gotten trapped in the system from just replacing a hose? and if so, would this cause overheating only w/ ac on...

 

Sounds more like a thermostat only partially opening. I could be wrong, and I hope I am. The engine clutch fan (sounds like a pickup truck fan) engages when the engine is hot taking off from stop lights right? I'm not talking about the electric fan that turns on high/low with the AC.

 

I've been driving w windows open and radio off since this happened, listening for anything diff, and I didnt notice the sound of any fan engaging pulling away from stoplights. Where is the location of the engine clutch fan? I noticed when the car was running in my driveway, all three fans (front of radiator, one behind, and one behind radiator on pass side), were running when Air or heat was on. Also, I know parts **** the bed early sometimes, but the thermostat was replaced last year along w t-belt, waterpump, and seals/tensioners(complete kit from blauparts). Thermostat was the first thing I thought of. I really need a good way to diagnose this for sure before I start replacing anything by process of elimination...Thanks for your help

 

my OEM Audi thermostat gave up after 2.5 years and 25k on it. The mechanical fan is the only fan that is connected to the engine. It spins all the time slowly, but when the engine is hot, it will speed up. When it does, it is noticeable. Also, do NOT drive your car if it gets that hot. You will ruin your engine.

Look at the second picture down in this forum post. The only fan you see is the mechanical fan.

DIY: 2.7T Timing Belt, Waterpump, Thermostat DIY, no lock bar.

Watch, well listen to this youtube video. The sound you hear, the whooshing is the fan clutch. It would be quieter in our Audi but still you would hear it. Mine only engages in stop and go, or when the engine is hot. I would say mine only engages a few dozen times a summer (MN summer). When it does, it will turn off again when I get about 30-40 maybe.

 

Also, do you have access to a vag-com? Maybe your radiator is plugged. While your car is running and at operating temperature, can you see coolant spurting back into the bottle from the upper hose? Do not take the cap off, you can see the coolant with the cap on.

 

OK, I know the fan now...I just started her up in my driveway, and that fan was running immediately. Not normal I take it??Tomorrow, I'll have to take for a ride and see if its blasting every time I pull off from a light or not. DO you know if theres anyway without ripping everything apart to tell if this is the problem or not? Diagnostics scan etc?? I really dont want to bring it to the dealer...

 

I was looking in the tank while the car was running and didnt see any coolant moving into it...Bad sign??

 

I know a local VW/Audi guy down the road who has one, he charges too much for labor, but he has hooked my car up to the vag before for 20 bucks. Am I supposed to see coolant running up into the tank??

 

If the fan clutch was fully engaged when the engine is cool, it would help prevent the engine from overheating. The fan clutch speeds up and slows down with engine speed.

The vag-com can help in seeing what all 5 temperature sensors in your car are reading. You will need to go into the measuring blocks. Search google for Audi measuring blocks and you should find what you need.

As far as the coolant bottle, once the thermostat opens you will see the circulation of coolant into the bottle. The thermostat won't open until the engine is warm. Mine, which failed last week, wasn't opening at all. I saw zero coolant movement in the bottle even as the car was beginning to overheat. Once we installed the new thermostat, it was very obvious there was coolant movement. If I remember tomorrow, I will take a video of what I'm talking about.

Your current predicament is difficult to diagnose. I was just in your shoes last week. I didn't have any hoses go bad but all else was the same. How mechanically inclined are you? If needed, with directions, could you do your timing belt job?

If you continue to drive the car with it getting even 1 notch above the normal 12 o clock position, I feel you risk damage to your engine.

 

If you have a windows laptop, not a mac running windows, but a windows laptop running XP or newer a cheap 20.00 ebay vag-com cable will serve you well into the future. This is the cable I own. http://www.ebay.com/itm/Vag-Com-USB-...cab623&vxp=mtr