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macfresh
02-01-2015, 05:06 PM
My 01 A4 1.8t (awm engine) has been experiencing an overheating issue and I've been trying to figure out the problem and even took it to a shop to get fixed but it still has an above normal coolant temperature issue. I just wanted some input on what it may possibly be before taking it back to the shop.

Back story: It first overheated due to a loose hose which spilled out all of my coolant. Before taking apart my car, I decided to do a whole timing belt kit change so I ordered a kit off Europaparts.com. I went ahead and took apart my car, fixed that loose hose, and installed the timing belt kit myself where I changed out the all of the belts, water pump, thermostat, thermostat housing, tensioner, etc. After putting it back together I noticed that I had an above normal coolant temperature and decided to take it to the shop. The shop helped me out and found a leak in the coolant flange and replaced that. This is where my current problem stands now as I when I picked up my car from the shop, I noticed my above normal coolant temperature (with the coolaant temperature needle being between 12 and 1 oclock and sometimes rising).

What I already checked:
- That the cooling system was properly burped and bled at the heater core
- Boiled the new thermostat in hot water to see it it open and closed when cooled
- Ran water through the radiator to see if it was clogged but it is fine.
- No leaks anywhere
- Checked that the Water pump does work (video taped it spinning for a few seconds after starting the car with the thermostat housing disconnected and thermostat out)
- Non clogged lower radiator hose

Again, I just wanted some help to see if anyone has ever experienced this problem. I also want to try and save more money before taking it back to the shop. I've been looking all around the forums but wanted to start a thread instead. Some symptoms that I noticed is a warm to touch lower radiator hose.

redline380
02-01-2015, 05:10 PM
Bleed the system again.

Also, when was the coolant temp sensor last replaced? Have you used a laser temp gauge to see what it is really at around the tstat? Do you have good heat?

Koldham
02-01-2015, 06:30 PM
do your fans run?

Corrado_Guy
02-01-2015, 08:02 PM
Try taking the hose off of the metal bypass tube on the motor that goes to the expansion tank until coolant comes out of it. Make sure to hold the coolant tank up a bit so the coolant level is above the tube which helps push the air out. As the motor warms up the upper rad hose should start to get hot and when the thermostat opens the lower hose will get hot. If air is trapped in the head then removing the hose on the bypass tube will allow the air to escape. I have been lucky where I just fill the cooling system through the cap when it is dry and allow the cooling system to suck it all in. once it stops sucking it in I start the car and top it off as the coolant is being circulated and after about a minute I put the cap on and it rarely needs more. You have to make sure there are no leaks anywhere and your cap holds pressure properly so the system can pressurize.

macfresh
02-01-2015, 09:15 PM
Bleed the system again.

Also, when was the coolant temp sensor last replaced? Have you used a laser temp gauge to see what it is really at around the tstat? Do you have good heat?

Will bleed the system again. Not sure when the coolant temp sensor was last replace as I bought the car used 4 years ago and I did not ask (Just got into the car/Audi scene haha). I would I say that I do not have good heat even when the heater is on full blast. It makes me think I have a clogged/ bad heater core but looking to see other alternative problems.

macfresh
02-01-2015, 09:16 PM
do your fans run?

Fans do run.

macfresh
02-01-2015, 09:28 PM
Try taking the hose off of the metal bypass tube on the motor that goes to the expansion tank until coolant comes out of it. Make sure to hold the coolant tank up a bit so the coolant level is above the tube which helps push the air out. As the motor warms up the upper rad hose should start to get hot and when the thermostat opens the lower hose will get hot. If air is trapped in the head then removing the hose on the bypass tube will allow the air to escape. I have been lucky where I just fill the cooling system through the cap when it is dry and allow the cooling system to suck it all in. once it stops sucking it in I start the car and top it off as the coolant is being circulated and after about a minute I put the cap on and it rarely needs more. You have to make sure there are no leaks anywhere and your cap holds pressure properly so the system can pressurize.

I will try that method of taking off the hose from the metal bypass tube. I have not heard doing that before so maybe it will help. Thanks!

woolveren
02-02-2015, 06:47 AM
I would I say that I do not have good heat even when the heater is on full blast. It makes me think I have a clogged/ bad heater core but looking to see other alternative problems.

I was about to tell that it would be a clogged heater core.. Try flushing the heater core and see the problem goes away.

macfresh
02-10-2015, 09:59 PM
Late update on my car b/c I went out of town for a week and left the car with it's condition of still having an rising above normal coolant temperature after the car warms up.

To continue my effort to find out what's wrong, I drained the coolant and the took off my radiator completely to run water through it again. I flushed and back flushed the radiator and went ahead and reinstalled it. Put in coolant and did all the suggested burps I got in recent replies and I believe I got most of the air out of the cooling system. Car warmed up fine and then I took it for a drive and it still had a rising temperature (between 12 and 1 clock on the temperature gauge).

I'm thinking its a bad coolant temperature sensor but any other ideas?