Rear main seal leak? Help please!

I have a leak that REALLY looks like it's coming from the rear main seal. I can't find any oil beside what's dripping down directly underneath the rear main. It only leaks maybe 20 drops each time I park it. The catch is, it's a new (maybe 15,000 mile) Marshal long block, so it SHOULDN'T be leaking. So what else should I look at before I get really pissed off about this? Is there any chance that the shop that put it in damaged it? Cause I wasn't happy with their work at all. :dunno:

Common leak areas include the rear main seal, valve cover (at the very back) and the oil filter adapter. Happy trails!

Jim http://www.yuccaman.com/jeep/myjeep.html

Best way to tell 100% where the leak is coming from is get a couple of cans of engine degreaser and soak the pass. side, back between engine and firewall, and all around the RMS and flex plate cover. Then hose it off and after a couple of days when it comes back you can trace it back alot easier.

I would check the valve cover at the very back, thats where mine let go on my 90 with only 12k on the new engine, it would pour out while running. The tip off of where the leak was is how it was wet at the oil pan but not on the drive flange of the crankshaft. There were no other signs of a leak otherwise. I switched to a 96 valve cover and newer style gasket to eliminate the leaky cork for good.

Turns out that it is indeed a rear main leak (verified by a mechanic). It's a Marshall motor FWIW. I don't think Marshall's are problematic I'm leanin towards the shop that installed the motor based on past experience. Could be excessive crankcase pressure but I've already checked all my lines and they're clear.

What oil are you running? My very minor leak stopped when I went to Rotella 5w40 full syn. FWIW

That's what I'm runnin. But I hate the idea of having an oil leak, no matter how small, ESPECIALLY on a new motor! :gonnablow

Got a warranty with the shop who installed it? Sounds like you should take it back and let them deal with it if that's the case.

If it was a long block it probably came with a pan on it. if it did then it is a defect from the rebuilder. if the pan was installed by the shop at instilation then they are responsible. I would insist that the responsible party either fix it free of charge or pay to have it repaired. It may be as simple as pulling the pan, cleaning and putting some new silicon at the contact points between seals. (it is a two part rear main)

It's a one piece seal, Marshall is authorizing a claim for it to be replaced. I'm still thinkin it was the shop that screwed it up. I'll wait till I get the old seal out and see if I can tell how it got damaged or what happened. Cause you better believe that if it was indeed the shop's mistake that they'll hear about it. After getting it back from the shop I was missing valve cover studs, all my sensor wires were a mess. They were tangled and dangling and not all of them were plugged in. My primary o2 sensor hadn't been installed, they way overfilled my tranny so I was driving down the highway only to look in my rear view mirror to see a giant white smoke cloud trailing behind me. They didn't use any threadlocker on my header so it loosened up and blew out the gasket that I specifically told them to soak in water before installing, which they didn't do either. And to top things off, they bolted my intake manifold on top of the alignment studs causing my motor to fire on about three cylinders which took me HOURS and HOURS to diagnose. Oh, and it took them about a month and a half to do the swap.

I wouldn't take the old seal out if I were you....not before you find out what the company is going to do about replacing it.

If you take it out, that leaves the door wide open for them to say "well you damaged it when you touched it" (not necessarily in those words, but i'm sure you get what I mean).

Marshall has already authorized a mechanic to replace it so that's no problem I'll just get it from the mechanic when he takes it out. But I'm very curious to see what comes of it.

One-piece rear main seal? Interesting.

Jim