Bad thermostat?

[nein-reis]

Last weekend I replaced the entire engine harness (bought a new one since the one I put in with the motor was in bad shape) and broke the little blue sensor on the tstat. I bought a entire new tstat from the dealership and put it in along with the new harness. Buttoned it all up, new coolant and it all seemed good to go. Had a few air bubbles in the coolant system at first, but drove them out.

The car warms up very quickly now and will overheat within 10 minutes of driving every time. I know the harness is connected properly, and functioning. I'm not sure, but it is almost like the tstat is not opening. Could I have gotten a bad tstat from the dealer? Is there a way to test it? Any other ideas?

Annoying issue.

[B6Lovin]

sounds like it. have you made absolutely sure that you've burped it completely? when it overheats, is the coolant level still normal?

if you had the car drained of coolant, then filled it, drove it, and it overheats within 10 mins... then your tstat isnt opening. especially if you haven't had the BIG top-off after doing all that. you should have had to drive it a bit/let it idle with the heat on and then it'll suck down the reservoir and you top it back off.

im willing to bet that you still have a SHITload of air in the system if you're overheating that quickly.

[nein-reis]

I did have a shit load of air in the system. But its all completely out now, I drove all the smaller bubbles out and did do a few big top offs. The fluid level does not move at all now until it overflows from boiling. I'll pull out the tstat AGAIN and trade it in at the dealer, maybe I can get some free coolant out of the deal. Really fucking annoying.
The lower radiator hose is still cold after it overheats, another reason I think it is the tstat.

[rbj325]

I had a similar issue replacing the thermostat on a non-audi car and it ended up being air bubbles at the thermostat. The air bubble caused the thermostat to not open because it wasn't reading the correct temperature due to the air bubbles. After some bleeding magic it worked fine.

Not sure how many new thermostats fail but I suppose it's possible.

[alhoward101]

I've had t stats fail from factory, j/w are u putting rtv around the t-stat? sometimes that stuff will get on the spring and stop it from opening. Will the car over heat at idle and the heat blowing?

[nein-reis]

Installed the new tstat today, the plastic on the other one was broken around the blue sensor... maybe that is an indication that the blue sensor was not functioning correctly? I don't know and it does not matter now.

The new tstat is in, and I'm trying to bleed out any bubbles but not much is happening yet. Had one big burp and had to completely fill the reservoir again, but it's still overheating but not as quickly as before.

With the heat on it does not blow hot and the lower radiator hose is still not getting hot at all.... completely cold even after it is driven harder and started to overheat.

I have no idea whats going on here.

[NickS4power]

I had the same problem a few weeks ago!! I replaced the tstat since it wasn't opening anymore and it didn't solve the problem. The problem was the water pump. The stock one is very cheap and it's components are made out of plastic. Mine cracked. Can't believe Audi actually made it like that. The new one they offer is made out of metal. It's much tougher. Hope it helps.

[bigblue]

Thatd be shitty if it were the waterpump after all that. But I guess its always worth a shot since the coolant isn't circulating.

[vinny.dtw]

There is channels on vag com that you can log to see if the fans and the t-stat is opening when it hits a certain temperature. Personally I think you still have a air bubble right now..Have you tried to relieve some of the air through the metal coolant screw above your intake manifold after you let your car sit overnight?

[MmmBoost]

Installed the new tstat today, the plastic on the other one was broken around the blue sensor... maybe that is an indication that the blue sensor was not functioning correctly? I don't know and it does not matter now.

The new tstat is in, and I'm trying to bleed out any bubbles but not much is happening yet. Had one big burp and had to completely fill the reservoir again, but it's still overheating but not as quickly as before.

With the heat on it does not blow hot and the lower radiator hose is still not getting hot at all.... completely cold even after it is driven harder and started to overheat.

I have no idea whats going on here.

Tyler try testing the thermostat according to the bentley manual.

When I was having my warming up issues this is what I did. I found out that I replaced my thermostat for no reason......because I had those little pellets in my engine getting caught in the seal not allowing the warmup circuit to close full.

......If yours is opening properly then there is some other cause.

[Audi Skate Snow]

vinny you sellt hat unit?

[nein-reis]

I don't have the stock water pump, put in the metal one when I built the motor... anyway pulled back the timing cover and there was no coolant leaking around it.
I'll keep checking for air bubbles, what a PITA.

[dougyfresh]

The harness should work fine. It worked 100% fine when removed from the car.

No visible coolant leaks?

[nein-reis]

Yeah, no coolant leaks aside from when it boils over from overheating. Everything else on the harness is functioning great, so I really doubt its the harness.

[rbj325]

It definitely sounds like an air bubble or failing thermostat. Have you tried jacking the car up at the corners to try and rock out any leftover air? Or the leave the bleeder open overnight like Vinny said usually works pretty well.

[bananas]

Bentley is pretty much useless in this case, but here it is anyway... http://dl.dropbox.com/u/1987709/Coolant.zip

[juttin3]

I keep reading about the cts sensor and all the issues it can cause. Does the b6 audi have this sensor in coolant flange. Have u tried changing it?