Second time in 8 months, my son's 96 A4 has a stuck thermostat. Car will heat up fine idling in the driveway, but as soon as you hit the road and go over about 30 mph,it cools right back down to the cold mark on the gauge, and of course thats accompanied with the check engine light, for "implausible temperature G52". First thermostat I pulled out, would open right around 190 degrees, but would not close until it got all the way back down to around 70 or 80 degrees. Be pulling the thermostat again this weekend, can hardly wait.

 

Get a OEM thermostat , stay away from anything made in China

 

Agreed - id also test the new one with a thermometer and a pot of water on the stove to be sure it opens and closes properly.

 

yeah when i did my tstat on mine, i did it while doing the timing belt and whatnot.. you've got the 2.8 right? that's a f'ing bitch to get in there. so anyways, when i did it, i put a non audi tstat in, and yeah, it broke within a year. so a few months ago, dead of winter, 15 degrees out, got into there and threw a real audi one in. hopefully it lasts another ten years 12 years like the first one lol

 

Finally got around to replacing the thermostat on the 96, took the cardboard sheet I had in front of half the radiator to get some heat in the car. Its easier the second time around when you know what has to come out to make enough room to work in the area. Heres the reason it stuck open this time.


The new OEM genuine audi part is on the left, the old generic aftermarket part is on the right, your looking at the back of the themostat(the block side). The disk on the aftermarket on is at least 3/8" bigger in diameter than the Audi version. This time that disk was hung up on the passage inside the water passage, it almost came out in two peices i had to pull so hard to get it out. It must have opened the first time, then slid over slightly to one side and got hung up on the edge of the passage behind the thermostat that connects to the front of each head. Car heats right up now, had to burp it twice so far, so hopefully theres no more air bubbles in the block now. Hopefully this is the last time I have to go into the front of this engine for quite a while.

 

I need to do this on mine soon. Since I only have 10,000 since the timing belt change, I don't really want to go through all of that.

Mark, did you put the car in service position to do the thermostat, or make enough room from the top? I am not looking forward to this...

 

Nope, car has an FRP RS4 bumper on it, so its not a fun job to pull the bumper to put the front end in the service position. I just went in from the top, did it with the timing belt on, and just removed the serpentine belt, power steering pump, and front engine plastic upper covers. Worked the thermostat cover out from behind the timing belt. It will come with some tugging, and sliding the timing belt forward on the right head cam gear, then just put everything back together and was good to go. Probably took about 2 1/2 hours total. You need 5 and 6MM allen wrenches to get the front engine cover off, and the socket head bolts on the power steering pump for both the pump and the ignition coils, I forgot what size the large nut on the steel line from th PS pump is, maybe a 22mm, ea 17mm socket to release the serpentine belt tensioner, a small pin (I used the back end of an 1/8" pop rivet) to pin the tensioner in the released position, and a 10mm socket to get the thermostat cover off. I just disconnected the spark plug wires and flipped the ignition coils out of the way, same with the PS pump, just took the front pully off and the steel line moved it over to the drivers side. Don't loose either of the crush washers on that bolt that seals the line to the pump. Takes a lot of wiggling and twisting to get that cover out from behind the belt, but it will come out.

 

i put zip ties around the timing belt so it wouldn't slip off, and moved it a little more than half way. don't force the cover, its pretty soft. it'll come out just gotta wiggle softly.

 

Chinese made crap..

 

Thanks! Good to know that it can be done from the top.