airbil

Thanks to all the help from this fine forum, the tstat for my new to me cabrio is done at last.
Like many Audi repairs difficult but not impossible and not to be lost was the dealers insistance that the TB had to be done too.
It took me way too long to do this but I spent extra time perusing the features of the v6 and cabrio. I wanted to do this since my heater core blew up and I thought the Tstat was the likely suspect to cause this.
For those that may want to do this here's what I would do next time. This may be redundant, but this is what I'd do for an "express" tstat install:
Drain coolant from radiator. Valve is located on the bottom of the radiator, drivers side.
Remove plastic top engine covers.
Remove plastic serpentine belt cover.
Take note of how the serpentine belt is routed.
Remove top pulley for the serpentine belt held on by three allen screws.
Move serp. belt out of the way.
Remove serp. belt tensioner. This is held on by only one large allen screw in the center.
Remove timing belt cover/s. You really just need to do the passenger side I think. I did both because I thought I'd have to.
Now's a great opportunity to inspect the TB for any obvious flaws.
Put a large pan under where the tstat cover is on the passenger side.
Remove coolant hose from tstat housing.
There are two bolts holding on the tstat cover, 8mm I think. Remove these.
Pulling the cover off the tstat requires twisting the Tbelt about 90o to get it over the tstat and off. This is perhaps the most difficult part. Impossible sez the dealer, but it can be done.
Carefully pry out the old tstat without damaging the housing or engine. It will just pull out.
Clean up around the housing and engine to assure a good seal for the new tstat.
Install new thermostat with relief valve at 12 oclock with new gasket Oring on the outside.
While carefully twisting the TB, slide housing over the tstat and bolt it back up.
Reinstall TB plastic cover/s.
The serpentine belt needs to be reinstalled but the two halves of the tensioner need to be de-tensioned (is that a word?) first.
I did this by using my bench vice to align the two holes on the tensioner and inserting a thick but short nail to hold the two halves in place. You'll see this readily apparent when you look at the tensioner.
Reinstall tensioner with the allen screw. I used a wee bit of loctite red on a few of the threads, but high temp loctite may be better.
Reinstall the top serpentine pulley with the three allen screws.
Reroute the serpentine belt making sure all the serpentines are aligned in the pulley wheels.
Remove the nail or drill bit or whatever was used to hold the tensioner halves in the "slack" position.
Reinstall plastic engine covers.
Add new coolant 50/50 mixture and 3 gallons total IIRC.
Start engine and let it idle 5 or 10 minutes noting coolant level.
I read about the need for bleeding the system, but couldnt find the valve or perhaps it broke off. So, I just let it sit for 15 or 20 minutes, topped off with coolant, let it run and took it for a short drive and somehow I think it filled all the air spaces. Temperature now normal and it runs okay.
I switched to red G12 coolant since that's what is in my two other Audi's this was a couple extra hour process and about 5 gallons of distilled water to flush.
All in all a nice "little" project that will cost you time and $35 for the thermostat and probably save many hundreds vs mechanic/dealer.
HTH someone, sometime!
Cheer's