C5RUZR

iTrader: (4)

So I was tracking down my oil leak on my fresh LS2 build. Threads here and here. After ruling out other possibilities and stripping down the rear of the car, sections at a time, I found the source of the relatively large leak is the rear cover. I can't say with certainty that the rear main seal is not contributing, but I'll be replacing it again anyway. I found a few other mentions of oil leaking from the upper bolts on the rear cover. Post #8 has a good picture of a leaking cover/bolt. Apparently there is a high oil pressure passageway in the back upper section of the block that the top section of the rear cover (should) seal off.

So, now that I know what my problem is, I have to tackle it. I've seen the TSB's on the block porosity and the new rear cover assembly which includes cover, gasket, rear main seal and new bolts. GM P/N 12633579. TSB #05-06-01-034K: 5.3L, 5.7L, 6.0L, 6.2L, 7.0L-Engine Oil Leak at Rear Cover Assembly Area (Engine Block Porosity RTV Repair Procedure)

Unless someone has other ideas for why the cover would leak so badly, I'm thinking I'll RTV the block according to the TSB and replace the rear cover with that new assembly. Anything else I should try? Or anyone with experience on a similar leak that recommends doing less? I was also wondering if I should try and seal underneath the head of the bolts or anything? And if so, with what?

Finally, I already pulled the rear cover (that had been installed with new Fel-Pro rear main seal and cover gasket). I noticed that the barbel oil passageway plug (oil gallery plug) was sticking out just a bit. The motor made good oil pressure, so I don't think the machine shop would have misinstalled it. But when I pushed on it, it moved slightly and "clicked" in. I haven't played with one before so I wasn't sure if it was normal to get pushed back into the cover by oil pressure. Then riding against the cover or if it should have been seated in more to begin with and stayed there. I see the FSM specs on that plug, but they seem to conflict. Some say the tolerance should be .08-.14mm inset into the block, while other diagrams show that tolerance outside the block. Is that just the difference between the old and new barbell plug design?

I couldn't get the camera to pick up the UV dyed oil stains as well as the naked eye, but here's some pictures of the rear of the motor. They show pretty well on the upper driver's side of the cover and trickle down, but in reality, the upper passenger side bolt holes were leaking even more!

C5RUZR

iTrader: (4)

PTFE sealant on the rear cover bolt threads possibly?

maroonls1z

I've actually never heard of high pressure causing leaks around the bolt threads? Did you use new bolts the first time?

SSSTANG#1

iTrader: (14)

Or teflon tape.

C5RUZR

iTrader: (4)

No, I reused the bolts (I think they were off my old LS1, but they could have been from the donor LS2). The cover was from the LS2 with new Fel-pro gaskets and seals. I was surprised to see it as well, but based on that picture from the GTO forum, it's not the first time although this one looks a lot worse to me.

Anyone have any knowledge of that oil gallery plug/position?

SSSTANG#1

iTrader: (14)

Doesn't have to be into an oil gallery, if the hole opens into the crankcase it can leak oil if not sealed.

C5RUZR

iTrader: (4)

Any more thoughts?