Thermostat O-ring ... which one

[VaSteve]

It looks like there's two of these...red and green. Which did you use and what's the difference. I did this job once, it's leaking again.

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_ENGoil_pg3.htm

[DUK]

Different manufacturers. I've got a green one and (knock on wood) no leak.

[dentist90]

The one I just took out was black (and brittle). Put in a red one. It better work!! I'll let you know in a few days.

[rusnak]

mine was green. but I don't think the o-ring should fail. Did you notice any damage to the o-ring when you got the thermostat out?

[dentist90]

That's true, the o-ring should last for 10+ years. It can be hard to determine where the leak is coming from up there. I couldn't tell for sure if it was the breather hose/gasket, the oil pressure switch or the thermostat o-ring. Took the shotgun approach and covered them all. The condition of my thermostat o-ring and the volume of oil coming out makes me think that was the problem in my case.

[rusnak]

statistically, almost not possible it's the case. The o-ring lasts me about hmm...5 years due to the weather we get here. The reason is that it takes a lot of heat and 60 psi of abuse.

When the oil pres switch fails, you have a geyser of oil shooting out of the top of the motor, and scary amounts of oil on the exhaust pipe. The only other thing it might be would be one of the crankcase breather hoses.

[john walker's workshop]

red o-rings are soft, green is quite a bit firmer. green lasts longer.

[rusnak]

Here's a picture that shows the engine (not mine) from the front, and why you know you have a leaking pres. switch or o-ring if you have oil dripping onto the exhaust cross pipe and oil on the top of the motor.

Applies to 3.2 and 911SC

[dentist90]

Originally Posted by john walker's workshop

red o-rings are soft, green is quite a bit firmer. green lasts longer.

Oh cr@p! Not what I wanted to hear. I've had the motor out 3x in 2yrs. The only good thing is I'm getting quicker and I get to recheck the torque of my CV joints annually!

[Steve@Rennsport]

Red is Silicone rubber & green is Viton.

Viton ones are superior due to its abilty to resist attack from petroleum products and heat.

[dtw]

I like the Viton ones, they seem to drop into the thermostat bore with a lot less fuss.

Had a 'rebuilt' 2.7 I installed last year (not my build) and among the numerous issues was a lake of oil at the back of the motor. Pulled the t-stat to find the original black o-ring, which was hard as a rock and fell off the thermostat in 3-4 crunchy pieces.