Engine gurus, oil leak question.

[GypsyR]

I've grown very fond of the new teflon rear seals. I've used them in a couple of applications to cure leaking OEM type seals. Only for one-piece type rear mains though. Doesn't sound like your mechanic has looked at these yet-FelPro #FEL2942RS.
Dunno about a rear seal "shedding" rubber to cause the oil to turn black. Sounds pretty far-fetched to me. Seems like most oil drips I've ever seen from the bellhousing area look black when found on a street-driven automobile. Doesn't matter where exactly it leaks from or how new the oil is, drips back there just look nasty. I don't claim to know exactly why that might be.

[frdnut]

Originally Posted by GypsyR

Dunno about a rear seal "shedding" rubber to cause the oil to turn black. Sounds pretty far-fetched to me. .

I agree...

[camachinist]

I used moly lube in a few places.

If you've got a leaking gallery/cam plug/rear seal, the molybdenum disulfide which collects at termination points can make the oil appear black.

[crickifur]

well that sounds like a smart comment, not exactly sure what it is but it sounds complicated enough to make sense hahaha

[gjz30075]

Originally Posted by GypsyR

Dunno about a rear seal "shedding" rubber to cause the oil to turn black. Sounds pretty far-fetched to me.

+2 on this thinking. I've got a pretty good leak in the rear of mine after several thousand miles from new; probably the rear main for some reason but the oil coming out is crystal clear.

Perhaps you're running really rich?

[pabear89]

Originally Posted by Maxum96

It's a brand new engine. The only part that was rebuilt and reused was the block. All top of the line high dollar parts inside and out. The oil is being blackened as it leaks out. I'm hoping the discoloring of the oil is a tip as to the source of the leak.

Taking a shot at your leak,
Possiable that the builder got some assy lube on the rear main.
I have seen roped (and 1 rubber) rear mains leak from it.
Seems the rope ones are prone to glazing from the assy lube and start leaking very quickly.
The discolored oil was the clue to looking there first.

[camachinist]

That's an effing manufacturer defect. Those have a metal support molded into them. Everything looks perfect otherwise. Was that a Fel-Pro seal? Well, I guess the builder got a wake-up call to start checking lip seals in detail. I work with them for a living and check each one with my finger and a light since they're usually holding a couple thousand psi of hydraulic pressure.

[Maxum96]

Originally Posted by camachinist

That's an effing manufacturer defect. Those have a metal support molded into them. Everything looks perfect otherwise. Was that a Fel-Pro seal? Well, I guess the builder got a wake-up call to start checking lip seals in detail. I work with them for a living and check each one with my finger and a light since they're usually holding a couple thousand psi of hydraulic pressure.

I guess I was a little slow and you posted before I pulled my previous message. I started a new thread because I couldn't update the title. The nick looks like it might have gotten cut with a razor blade.