kostantinos tsavidis

I need some help guys. I've have a mystery coolant leak that finally dealer found out it was the thermostat housing $900 later and now I saw coolant marks in my garage again, I looked under the car and I see that the drip is formed on the bottom of the housing they changed. I brought the car back and first they said they pressurized the system and they couldn't find anything and I said "well I am not crazy I have the picture to see that it's leaking" so the kept the car and drove it. Now the called me and said that the tech found a very minor leak from the water pump housing...... fix $1800. Can anyone tell me if the water pump house in anywhere near the thermostat housing and if it's a possibility that they are right because it seems that they aren't even sure?

Jack88

It could be right, could be wrong. It's hard to say without having eyes on it. I'd say it's a good shot that the thermostat housing was never an issue. Also, there are a lot of different engines available in the D4 A8, so specifying which you have may cue people in to specifics to each motor. There are 2 6-cylinders, 3 8-cylinders, and a 12 cylinder model. That's just in the U.S.

kostantinos tsavidis

It's a 2013 s8 d4 4.0 v8 engine. I got a call back and I went there had them put it on the lift and looks like it was forming a drop of coolant through the torx screw from the thermostat housing that make me believe the seal inside is pinched or not properly seated.

Jack88

The torque specs on those are not high, so overtightening it would be easy to do without a torque wrench, so that's a reasonable possibility.

cleex024

definitely...on my 335 before i was replacing the seals on the oil thermostat and didnt think it would need a torque wrench on it as i was only going to tighten it slightly...except the bolt just kept going lol...found out it only needs to be torqued to 11lbs. didnt realize 11ftlbs would be so little.

kostantinos tsavidis

What I believe is that when they replaced the thermostat housing the seal wasn't seated properly and since the housing is plastic leaked when temps flactuate.