jseklund

Ok, so I have been losing coolant for at least 6 months at this point, and slowly chasing down the issue. First I replaced my cracked coolant resevoir, then my leaking CTS and O-ring, then the leaking after-run sensor on the other side of the coolant pipe. At this point, I lose about half my resevoir in about a week...sometimes faster, sometimes slower.

A couple weeks ago, I decided it must be the aux. pump, so I pulled the manifold to find out that someone had installed a relocation kit for the pump and the valley pan was dry. I checked the relocated pump and it was dry.

Today I pulled the front of the car to look at the T-stat housing - and the housing looks to be dry. I just pulled the passenger side timing belt cover and serpentine belt tensioner after I got the car into service position...but I didn't see ANYTHING on the front of the engine.

While I was in there, I noticed a big glob of gel coolant on top of the valley pan this time (ironic huh?)- so I am guessing the plastic elbow that they used in place of the pump has cracked and I just missed it because it wasn't as bad before.

I did notice a very small amount of orangy liquid on the TOP of the t-stat housing, but it looked like it may have come from the valley pan area.

I didn't notice anything around the tensioner when I took it off.

I decided I will pull the throttle body and try to replace that elbow over the valley pan tomorrow - so I started buttoning up the front end.

The funny thing is that when the car was up, it wasn't leaking at all. I can NEVER find any trace of coolant on the underside of the car.

I put the lock carrier back and as I bumped it into place, the car shook and some drips started coming off the side of the oil pan - maybe 1 drip every 4 seconds.

I could look up and see the coolant appears to be dripping down from behind the alternator.

My question is - do you guys think this is a waterpump/t-stat issue? Or is it just as likely to be coming from the valley pan area? I'm just curious ...I will probably be doing the timing belt in another 3-4 months and will probably just keep topping up until then if it turns out to be the t-stat or water pump...

Huskerbob

I had the exact same condition on my A6. Dripping from right above the alternator and it was the t-stat. (I think it ruined the alternator as well.) I think when you pull it apart for the timing belt you will see the evidence of the t-stat leaking.

PerryLa03

I think you should look at the gasket around your water pump that could be bad also. Then maybe replacing the gasket first.

Huskerbob

Maybe, but since he's already there just go ahead and do the whole job. The timing belt deal encompasses the t-stat and water pump.

LakeTahoeQuattro

I have a slow leak on my 2.8 as well. I searched for hours and could not find a leak. Please keep us posted with your progress.

jseklund

Thanks for the replies! I haven't had time to go back in there, and the leak is so slow...I am going through a gallon of coolant every 4 weeks approx. - it will cost me very little to just leave it until the timing belt needs replacement...which should be in the next 3 months or so...I may do it sooner depending on funds. I am thinking that it has to be the waterpump or T-stat. I will update when I finally go in there...but it may be a little while.

rocketman4321

There's also a small lower hose connection to the t-stat housing (at least on my 2.7t). Like the t-stat and housing, it will drip onto the alternator--it's all the same path for the liquid. The hose is <$20 and can be swapped without going to the service position, but it'd be a lot easier to do it with better access.

SloopJohnB@mac.com

My first thought was have you heard of a pressure tester? They're not that expensive although the #%$$#% adapter for the Stant cooling system pressure tester cost me around $30 or so. Fire up the tank and get the engine hot (I'd leave the coolant reservoir cap off because it will vent coolant when you take it off to put on the tester) and then shut it off and hook up the pressure tester. Run it up to 20 psi or whatever your cap is set for in bar(s) and THEN start looking for leaks.

SloopJohnB@mac.com

Get. A. Pressure. Tester.