what does the lower rad hose feel like when car is warmed up? Is it hot too? or fairly cool?

describe the procedure you used to bleed the system.......

I would try another thermostat, sounds like it doesnt open. The top rad hose will always be hot regardless.

 

I haven't checked the lower hose. It was cool as far as I can remember. (I'm away for the week on business, so I can't) I'll check it when I get back.

As far as bleeding the system, the overheating problem went for 5 months before it was bled. (timing belt/water pump replacement). I'm confident that's not related to the problem. Besides I've bled it twice since the replacement. Raised the coolant reservoir, unscrewed the cap and reconnected the hose by the firewall whenthe airwas bled out.

Now I haven't changed the thermostat. The heating and temp guage have been fine. I didn't change the thermostat when I changed the pump/belt because I wanted to rule out the problem. Itry not tochange too many things at once.Either you don'tdiagnose what caused the problem or you have a new problem (the troubleshooting multiplies...aaahhhh)

Ifthe thermostatdidn't open wouldn't the top hose be cool because the hot coolant isn't passing through? I thought that is why the top was checked to rule out the thermostat. My'98V6is at 120k so a thermostat replacement can't be too far ahead. When I get back maybe I'll change it. I don't have much left that I haven't changed.

Am I wrong about checking the top hose????

 

does the coolant fans cut in now?? also check the lower radiator pipe isn't collapsing due to age ( it gets very soft ) when hot and collapses

[IMG]local://upfiles/12092/34367922301A4FA3B25AC6A18DD33A74.jpg[/IMG]

 

For testing purposes, I'd pull the thermostat out and try running without it. Not a good idea longterm, but should be fine to test with.

Mike

 

Consider this case closed. It was the thermostat. Hats off to acetrebo.
The last thing that I replaced turned out to be it. I ruled it out because I was told to "check the top rad. hose, if it's hot it's not the thermostat". It's at 120K so it was probably due anyway. Luckily I changed the water pump & timing belt last month so getting back in to the engine was easy. I can see whyAudi recommends changing the pump, belt, and thermostat at the same time .....only they charge $1500+for it.
I managed to do it all for under $250. I even did it w/o the camshaft locking tool. Next time I'll probably pick one up. You REALLY don't want to misallign the camshafts. See below. (From a Porsche 914)

 

That looks like fun! Good thing T4 cases are cheap as dirt... (comparatively)

You on 914world.com?

 

I wish, I wish.I just couldn't find a good Audi blown engine picture and a picture says a 1000 words.

 

Thank you, thank you.
Upper hose will always be hot, cause the thermo is in the bottom!