Rear Main Seal Leak?

[buster1015]

A few weeks ago I began to notice oil under the car when parked. I wiped the underside completely clean and ran the engine to check for leaks in the area. I let it run for at least 20 mins and the oil temps got up to about 190F. Still nothing.

I shut the engine off and within a few minutes I noticed a very small stream of oil coming from the engine to transmission mating area. The drip follows along the case part line and I'm guess it is coming from the rear main seal, can't think of anything else there.

About six months ago I had replaced the rear main seal while replacing the clutch and was extremely careful to not damage the metal surfaces while removing the old one. I used the OEM Kaco brand (999-113-426-41-M204). Tapped it into place using the old seal flipped backwards. Used plenty of oil along the internal seal surface that contacts the crankshaft and none on the outer.

I suspect that oil is leaking between the crankshaft a seal. Perhaps once the engine is running the inside of the seal is pressurized slightly which is enough to push the seal open against the crankshaft. With the engine off and no pressure the seal retracts just slightly and lets oil by.

That said,
Is this a low quality seal and are there better ones out ther I should have used?
Should I drop and replace? Doesn't seem worth it to simply put the same part in.

Hoping for someone with more experience to chime in since trial and error would require dropping the engine :/

Patrick
1987 Carrera Twin Turbo, G50.01 trans

[Discseven]

Patrick,

Your description & photo does suggest a rear main leaking

I've seen exactly the same on my 3.2.

Am showing you my front main seal going in... I used the same brand in the rear and can recommend this brand whatever it is. Perhaps you know the brand from looking at it. If you want... I can look for the brand in my parts file.

I do the same lubed inside and dry outside installation of these seals as you.

[kodioneill]

Smell the oil to check for transmission front seal leak. I think it's very important to use the proper seal installation tool for the rear main seal it has to be positioned perfectly or it will leak.

[Bob Kontak]

Originally Posted by kodioneill

it's very important to use the proper seal installation tool for the rear main seal it has to be positioned perfectly or it will leak.

kodioneill - Expand on that a wee bit. I installed a rear main seal in my 81 in 2009 and have had no problems. I did not use a special tool - but I was drinking. :-)

I know you have a squillion times the experience that I do. Did I just get lucky?

Not arguing - just asking.

[kodioneill]

Hi Bob I think it's a crap shoot without it but with it it's 100% right every time. I'd hate to r&r the engine and transmission for the lack of the right tool.

[buster1015]

Thanks for the input. Since I use Brad Penn oil it is easy to identify that this is motor oil from the green color. Since it's not leaking while driving I think I'll just put a pan under it while I park in the garage and drive it for the next month or so. I replace the seal when I do the next valve adjustment.

Per Wayne's book he recommended tapping the new seal in using the old one flipped over. Perhaps I tapped it in 1mm too deep. Due to the difficult access I'll pickup/borrow the installation tool for the replacement.

[tobluforu]

Put valvoline in and I bet ya the leak will all but go away, worth a shot.

[T77911S]

thats odd that it does not leak while driving.

make sure it is not the sending unit, or T stat or even the vent hose on the back of the motor.

[buster1015]

A couple of weeks ago I went through the trouble of removing the intake and fiberglass cover to inspect the top of the engine. It was clean without a hint of oil which means my previous repairs to the triangle of death, about a year ago, seem to take so it must be the rear main seal.