New thermostat and housing won't stop LEAKING!!

[coolguy]

Hey guys need some help. I recently replaced my thermostat housing, everything was fine. Then as I was driving my upper connector for my radiator broke off. I ordered a new radiator, belts, thermostat. put everything on and start it up, no matter how tight I put the housing on it still leaks while the engine's running. I've already taken it off twice now and can't fix the problem!! The only thing I did differently before I started this procedure is I bought a 182 degree t-stat instead of the 190 or whatever. and I didn't replace the round O-ring that goes around the thermostat because the thermostat didn't come with one and didnt notice until I got home, and it was only about a week old or so. maybe 2. I'm going to buy a new o-ring from the dealer tomorrow but do you guys think there's something else causing this or should I have replaced the O-ring no matter what?

[jnyost]

Always replace the o-rings. Work with a vendor who will help you catch small stuff like that or post on here.

Another thing I always suggest is to purchase an OEM water pump gasket. The one with the pump is junk.

Jared

[BimmerBoy740I]

Always replace the o-rings. Work with a vendor who will help you catch small stuff like that or post on here.

Another thing I always suggest is to purchase an OEM water pump gasket. The one with the pump is junk.

Jared
+1 always use OEM gaskets for ANYTHING!!!

[killcrap]

early e39 with m52 engine 1996-1998 the mating surface of the thermostat becomes pitted. which causes the leak you are describing. you can fix this by sanding or grinding down the surface.

[coolguy]

are you talking about sanding the groove that the thermostat sits in? what a piece!