Major Oil Leak (from where???)

[fmj78]

Question: Has anyone seen a leaking oil pan gasket leak so much that it pools in the bottom of the bell housing?

I just did a clutch job, including rear main seal. Put it all back together, took it for a drive, and came back to a large amount of oil dripping from the bottom of the bell housing. Obviously I thought I screwed up the rear main job so I did it again. Put it all back together, took it for a drive, same pool of oil.

Transmission is back out of the car and the rear main is dry, as is the housing. Right under the housing corners are wet, driver side more than passanger. I can't find any oil above the bottom edge of the rear main housing on the engine. The bell housing is soaked.

Me and three other guys at our shop are stumped where this oil is coming from. Dipstick tube? Oil pan gasket?

[dn010]

Warped rear main seal carrier?

[fmj78]

certainly possible, but would expect it to be obvious where the oil was coming from. The joints look dry.

[DMCMW Dave]

Did you tighten the allen bolts that go into the block all the way before you tightened the two that come up from the bottom? If you did that will leave a gap at the bottom mating surface that won't seal. Did you use anaerobic sealer on the bottom flange surface (no gasket there)?

[mark w]

Did you tighten the allen bolts that go into the block all the way before you tightened the two that come up from the bottom? If you did that will leave a gap at the bottom mating surface that won't seal. Did you use anaerobic sealer on the bottom flange surface (no gasket there)?

so on the rear flange, you should tighten the bottom two first and use anaerobic sealant on that joint. NO RTV!
then tighen the other 5 allen head bolts.

[fmj78]

First go was with anaerobic, second with "the right stuff"

I'm not convinced this is motor oil. It doesn't smell like gear oil, and looks the color of motor oil, but the input shaft seal (NOS) is leaking when I tip the transmission forward.

I guess it could be both, but I can't find any source of a leak that would explain this much oil.

I've got a new production seal coming. Will give that a go.

Thanks for the notes.

[DMCMW Dave]

First go was with anaerobic, second with "the right stuff"

I'm not convinced this is motor oil. It doesn't smell like gear oil, and looks the color of motor oil, but the input shaft seal (NOS) is leaking when I tip the transmission forward.

I guess it could be both, but I can't find any source of a leak that would explain this much oil.

I've got a new production seal coming. Will give that a go.

Thanks for the notes.

Input shaft seal on the trans should never leak. That would destroy the clutch in pretty short order. There are two leak points on that, either the double seal that goes around the input shaft or the o-ring between the tube and the bellhousing.

To answer your original question, I've NEVER seen an original-build oil pan gasket leak. They were apparently made of asbestos and JB weld. (J/K). Aftermarket ones are not as good, I don't believe true factory originals are available.

[chris williams]

Input shaft seal on the trans should never leak. That would destroy the clutch in pretty short order. There are two leak points on that, either the double seal that goes around the input shaft or the o-ring between the tube and the bellhousing.

Mine leaked from the same place for years and assumed it was the rear crank seal...... Then I bothered to smell the oil and realized it was G/box oil! So yes I would do as suggested and check the above!

Chris

[Helirich]

How about clean it up and take it for a short drive. (1/4 of your last drive) Might be easier to see where it is coming from.

[fmj78]

Definitely input shaft seal. Oil came out the tube when the trans was tipped forward. It probably would have been fine to leave the original one in there, but I got a bad case of whileyerinthereitis and replaced it with a NOS one.

Trans is back apart, should have the new seal tomorrow.

Will report back after the next test drive.

[fmj78]

SUCCESS!

The oil leaking was definitely from the transmission, and 99% sure it was my installation method of the input shaft seal that caused the problem.

#RTFM

decouple the shaft, install seal, recouple shaft, tap tube on the seal.

Took it for a spirited drive yesterday, back on the lift and dry as a bone under the car.

[82DMC12]

Did you tighten the allen bolts that go into the block all the way before you tightened the two that come up from the bottom? If you did that will leave a gap at the bottom mating surface that won't seal. Did you use anaerobic sealer on the bottom flange surface (no gasket there)?

Hi Dave,

When you mention the allen bolts, are you talking about the bolts that hold part # 102023, the bracket that the actual rear main seal is in, to the lower crankcase? I see there's a gasket between those the bracket and the crankcase. The shop manual doesn't say anything about changing that thin gasket in the section that discusses changing the rear main seal so I would never have known this detail. Any other details you can provide would be great since I think I have a small oil leak in that area that I'll address one of these days.

[DMCMW Dave]

Hi Dave,

When you mention the allen bolts, are you talking about the bolts that hold part # 102023, the bracket that the actual rear main seal is in, to the lower crankcase? I see there's a gasket between those the bracket and the crankcase. The shop manual doesn't say anything about changing that thin gasket in the section that discusses changing the rear main seal so I would never have known this detail. Any other details you can provide would be great since I think I have a small oil leak in that area that I'll address one of these days.

I suppose you could replace the rear main seal and leave that plate in place, but since in my experience the allen screws are often not much more than finger tight you definitely want to take it apart and do it correctly. It's also a lot easier to change the seal on the bench than on the car.

If you buy a whole clutch kit it comes with the rear main seal and that paper gasket.

The only other "trick" is that the paper gasket is make longer on the open ends than it needs to be. You are supposed to match it to the plate and trim the ends off with a razor blade. Use sealant (anaerobic) on the paper and on the bottom non-gasketed surface.

[82DMC12]

Thanks Dave. Quick follow up. When should one use anaerobic sealant versus hylomar? What's the difference and what is the application? I'm getting back into some restoration this year and trying to brush up.

[Ron]

Same thing...
http://www.valco-hylomarproducts.com/anaerobic.htm

[dmc4087]

SUCCESS!

The oil leaking was definitely from the transmission, and 99% sure it was my installation method of the input shaft seal that caused the problem.

#RTFM

decouple the shaft, install seal, recouple shaft, tap tube on the seal.

Took it for a spirited drive yesterday, back on the lift and dry as a bone under the car.



Hi there - I have the same issue, did you need to split the gearbox to replace that lip seal?

I think I need this O-ring 103103, and the lip seal 103177

Cheers