my 2001 225 tt coupe had been running hot, according to the gauge. took it to my mechanic who has a lot of experience with Audis. Left it with him all week. He put it on the computer and said it was hotter than normal but not as hot as my code 49 showed. Late yesterday afternoon he finally says the thermostat probably isn't opening all the way and I should bring back next week and he'll get right on it. Why the heck didn't he go there to begin with when he said it is what he suspected in the first place? Just goes to show you that even the best mechanics can blow it from time to time. Excuse me for blowing off steam (me and the car)

 

Thermostats are easy to change and are like $13.00 at Pep-Boys

easy way to test the old one as well, take it out and put it in a pot of water and boil the water and see if the thermostat opens up, if it does then the thermo is ok if it opens slightly then bad, get new one..old skool test

 

Okay. I'll give it a shot. Anything on here about how to go about changing the thermostat?

 

Yes! plenty of diy's here or on the Audizine.com
You can even google How to change a Thermostat on an Audi TT

 

How many miles on your TT. Usually T stats are good for about 80-90k miles. If this does not help then it could be the plastic waterpump impeller dis-entegrating. Has the timing belt been change and the water pump with it? If you did not buy or specify the metal impeller and when you change out the the Timing belt, if this has been done, this could be it.

A Way to to check for the impeller is while it is running check the radiator hoses and if one is cold and the other is hot then you have a problem. This means the cooled water is not circulating through the system. I experience this on my sons Mazda MX6 having plastic friggin impeller. Who ever the genius that thought of this one should be shot.

Not ******* you but have "you" checked the fluid level. Don't rely on anyone but yourself. You are your best friend when it comes to car mechanics and can get ripped off if you are naive. Always a good thing to start learning. This **** cost as much as a doctor nowadays. I have save thousands upon thousands doing my own maintenance over the years. Plus doing some big time jobs like engine swaps. It is all nuts and bolts and like a puzzle you just learn to put them back together they way they came apart. Now diagnosing is the only part that you must learn. Wrenching is not hard to learn. I am doing my Timing belt in the evenings right now. Great Tutorial I go off here to do it. That is all you need. Bentley Manual is great to own or and Audi manual.

 

It was the thermostat. finally, peace of mind again

 

Great to hear this. This is the typical reason for overheating. You know I just replaced the timing belt this weekend and had 60000 miles and the water pump looked perfect and it was the plastic impeller. My car is the 2000 model. So this maybe and isolated material problem? Either my belt was changed which I doubt or their is some undue hysteria about this? The tensioner was rock solid. I could not squeeze it in like the new one. I have done several other cars and have seen tensioners that were spongy and they held the belts on.

 

Well in most cases the plastic impeller ends up in pieces. Like I said in most cases!
That is why everyone suggests the metal impeller pump!

 

Now that you all Jinxed me!!! I changed my thermostat, yesterday!
Now when I stop the temp gauge goes 1/4 past half! with new thermo!
Fluctuates the same. The old thermo would go 1/4 past half then I turn the A/C on and stays cool. WTF!!! What would happen If I run without a thermostat?
I just might put the old one back in. Fluid is full and fans kick on with A/C not without.
I changed the fan module and the green temp sender!
Clueless. No leaks! Maybe the temp dash gauge is wack!
Anyone have any other suggestions! How does the no thermo sound?

 

LOL! That seems to happen. Don't go without the T Stat. They hold the Antifreeze in the radiator long enough to let it cool the hot incoming fluid. Regulates the temps and will most likely run hot without it. New stat have a different Temp range when it opens? Maybe buy an OEM for twice but piece of mind? Is this an O'Reilly or other aftermarket Stat? How many miles you got on it? Check the oil. Head gasket? The oil will look chocolate brown if so. I am crossing my fingers while writing this (hunt and peck) so as not to jinx you again. LOL! Hey as long as it does not run hot it is all good. Could be that with this 100+ degree temps it is the reason and you never noticed this paid attention to it before?