Rear main seal - install forward or backwards?
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I've ran into a bunch of posts that recommend installing the new style OEM rear main seal backwards on boosted application.
I put a new OEM rear main seal the recommend way (this side out markings facing out) on my forged 370 when I assembled it. It took quite a few tries to install if so I may have just jacked it up suring the install. It's got a steady drip leak at idle (18" vacuum) so I need to replace it before I put it under any boost. I thought I'd ask before I start dropping my 4L80E and transfer case. It's a solid 8-10 hour job so I'd rather not have to do it again.
By the way, I'm running 5/8" hose from each valve cover to a catch can so I haven't had any issues with a boosted crankcase focing oil out the seal on the original motor.
Also, any preference for OEM or Felpro?
Rick
I put a new OEM rear main seal the recommend way (this side out markings facing out) on my forged 370 when I assembled it. It took quite a few tries to install if so I may have just jacked it up suring the install. It's got a steady drip leak at idle (18" vacuum) so I need to replace it before I put it under any boost. I thought I'd ask before I start dropping my 4L80E and transfer case. It's a solid 8-10 hour job so I'd rather not have to do it again.
By the way, I'm running 5/8" hose from each valve cover to a catch can so I haven't had any issues with a boosted crankcase focing oil out the seal on the original motor.
Also, any preference for OEM or Felpro?
Rick
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I've heard both ways as well. I remember seeing an engine builder say they have better luck installing it backwards. I put mine in as gm intended. So far my 390 hasn't seen any boost but its been in nearly a year with no leaks.
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Just be careful not to force it too much. I didn't have a piece of pipe big enough to go that route so I used a small rubber mallet, a block of wood, and my fingers. You should be able to feel when it is evenly seated.