Oil Pan Gasket Or Rear Main Seal?

[clawhamm3r]

What do we think, boys? I want to say oil pan but the way it angles down right to this spot I could see it being rear main and running down the seam to here...but maybe not. I cleaned the whole thing up with a couple of rags and cans of BPC and it's just sat in the air for the last 3 days and this is what I've got (not even running). It's seeping from up where the fresh oil trail is as well as the dirty spot lower down, though the dirty part could just be residual BPC pooling. No oil around the access holes in the bellhousing.

[mrgizmo04]

Cpv, half moons on the valve cover dry?

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[benzthis]

^was going to say cpv.

[clawhamm3r]

I was going to say BTW the CPV is bone dry (did a viton oring like 8 years ago) but figured the picture showed that it was coming from the bellhousing would indicate that haha. I did check it first hoping for an easy fix...

I'll double check the valve cover...but would run down in/through the bellhousing? I'd take that over rear main or oil pan haha.

[mrgizmo04]

There was a thread on oil leaks on the old forum. When I was installing the valve cover I pinched the intake cam wire (didnt know it at the time), oil leaked down the back of the engine and came out between the engine and the bellhousing. I thought it was the rear main .

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[natty99]

exhaust CPS o-ring might have sh!t the bed. Check there when you're checking the valve cover gasket.

[clawhamm3r]

There was a thread on oil leaks on the old forum. When I was installing the valve cover I pinched the intake cam wire (didnt know it at the time), oil leaked down the back of the engine and came out between the engine and the bellhousing. I thought it was the rear main .

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Don't give me hope like that lol. I did just do a valve adjustment like 1200 miles ago so maybe...

[bigjae46]

I would say oil pan gasket.


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[///Mac]

I did my oil pan gasket and CPV a few months ago and immediately had nearly identical seepage as seen in the pic. My OPG and CPV were definitely leaking, so I don't question replacing them vs. the rear main seal. (It was like the Exxon Valdez down there and I had to start somewhere 😆)

Assuming the new OPG and CPV were installed properly, the remaining seepage on my car would be from the rear main seal. Wish I could confirm, but I won't get to it for a few months.

[FBloggs]

Hard to say.
The right side of the block and the bellhousing have been washed..
1,.the dark shadow in the pan webbing where the mating bolt is located.
2,the thin dark line at the bell housing/oil pan join seem point to a past CPV leak that has been sorted, but with rubber o'ring that may be failing again.
A rear main seal leak would bias the oil stain more to the center rib of the transmission since it is not exposed to moving air until it breaches the engine/oil pan seam.
How many miles are on the car?
I'd give the leak a little more time to make a more recent track of oil.
I replaced a CPV seal few months ago. When they fail, the leak worsens quickly. It soils the block outside of cyl #6 and runs down the block at the block butress. The the oil spots the floor with 1 inch drop stains.
Btw,if you pull the chassis reinforcing plate and check the nature of the oil trapped, you can rule out the RMS by how far forward the stain is on the plate.
edit:
should have pictured before the cleaning..
the size and nature of the oil stain on the chassis reinforcing plate will be the best clue.

[nuc1]

Had the same leak. Thought rear main seal. Turned out to be transmission front seal. Tranny fluid mixed with some dirt/grime in the bellhousing....

Mike

[clawhamm3r]

Trust me, the CPV is bone dry. First thing I checked. It was leaking like 8 years ago and replaced with the viton oring.

Second issue is I also have a leak coming from the front, I believe the VANOS line. I actually had oil from the sway bar / AC compressor bracket all the way back to the transmission past the drain bolt. Impossible to tell where anything was coming from hence the cleaning. But the CPV was dry in all of that lol.

Next step was to set up some fans and let it idle it but I haven't gotten that far yet. I will fish my hand back by the firewall and see if it comes back covered in oil from the valve cover. If I can get away with just reseating the valve cover and replacing the VANOS line I'll be doing cartwheels. Car has 115k miles btw.

[Mspir3d]

I had oil there last year. It drove me nuts and I even pulled the transmission at one point. I replaced the oil pan gasket, the rear main seal and I put a bead of silicone filler where the rear main seal housing meets the oil pan. After many, many hours of tracking it down, I found it was coming from the intake cam sensor.

my oil leak in the front turned out to be the valve cover gasket. It was leaking at a tiny spot above the vanos gasket. A very small bead of silicone on top where the vanos meets the head stopped it thankfully. Oil can come from weird places and it's hard to find the origin especially when it can travel along cracks.

[sapote]

If the crank rear seal is leaking then why we don't see the oil drops at the bottom but starting on the RH side of bell housing?

[clawhamm3r]

Well, I went out and reached back behind the valve cover the but unfortunately it was dry. So I idled it for 30 min and got back under and confirmed I have at least an oil pan gasket leak in two places. Guess it's time to do rod bearings too.

Bonus pic of the CPV...Viton oring going strong 8 years later lol.