C2 BB oil leak

[Darwin K.]

I have read most of the archived posts on oil leaks, of which there are many.
I couldn't find a real answer to my question, which is:
I have a leak with oil(engine oil not transmission oil) slowly leaking from the bell housing/fly wheel cover junction even when the engine is cold and hasn't been run in days.
I can't see the source.
Can a rear oil pan seal leak or rear main bearing seal result is such a leak?
Thanks for your ideas,
DK

[Mark E.]

Re: C2 BB oil leak

If you really have an active oil leak from an engine that isn't running, check the oil pan drain plug. They often leak if the washer isn't replaced. Or maybe the oil pan is damaged and has a crack/defect below the oil line.

Also check the valve covers. Oil pools at the back of the cylinder heads because of the engine's tilt, and can leak for days from the VC gasket. The stamped steel BB covers are notorious for bending and leaking.

But keep an open mind. There may be a small leak anywhere, which takes days after shut down to travel to the lowest point of the engine before it drops on the floor.

Remove the inspection cover, and clean the entire engine and transmission case well with Dawn dish soap diluted with warm water using a spray bottle. Then wait and watch for oil leak paths; a black light can help you see these.

At the risk of being wrong, I'll say it probably isn't the rear main oil seal. Those only leak while the engine is running, and the residual oil usually stops dripping within an hour or two after shut down.

[Darwin K.]

Re: C2 BB oil leak

Thanks Mark.

I was also thinking that there should not be a cold oil leak from the rear main seal.
I forgot about oil pooling in the heads because of the engine tilt.
It seems like the valve covers are often the culprits as are the seals.
I had re-torqued them, but it had no effect on the leak.
I may need to replace the gaskets and check the VC for bends etc.
I will keep looking.

Is the oil depth high enough that it could leak through a faulty rear oil pan seal?

DK

[Domenic T.]

Re: C2 BB oil leak

Darwin,
i agree with mark and oil drips down. I always run my fingers in back of the block just under the valve covers to see if there is fresh oil on my fingers. The rear seal should not leak with the engine not run for a while unless a bunch of oil is working its way down after a run.

Dom

[Peter M.]

Re: C2 BB oil leak

Hi Darwin,
I had the same problem with my 67. It would drip just sitting, days after the engine had been run. I did the same checks Mark and Dom are suggesting and couldn't come up with anything conclusive. It appeared to be coming from the oil pan gasket so I changed it this past winter and it hasn't dripped since. I have the dash out of the car and haven't run the engine yet so I can't say for certain that the leak is fixed. And yes I did fill it back up with oil.
Kind Regards