Rearmain Leak On New Crate Motor

[Ardee83]

I ordered a brand new 350 crate motor from JEGS. As soon as I finished installing the motor and took it for its first spin, the rear main was leaking. Since it has the 3 year GM warranty I took it into my local Chevy dealership, that was a fight the serviceman was adamant it was impossible for the rear main to be leaking on a brand new motor. I told him I'm 99.9% sure it's the rear main I've had it on a lift and traced the leak it leads back to the rear main. So after a dye test guess what I was right leaking rear main. So they replaced the rear main I drove it for 3 miles and the new rear main is leaking. I called the dealer back let them know the rear main was still leaking, his reply again I don't how it could still be leaking its brand new. My reply ya I know and so was the rear main when I got it. So to make the long story short the dealer was unwilling to replace the rear main again. So I have decided to drive 15 miles to another chevy dealership I made them aware of the situation with the other dealership and have asked them to replace the rear main for a second time and to ensure that it is repaired and if not to keep the truck until they discover the issue that is causing the rear main to leak. So my question for you guys what could be a possible underlying source causing oil to leak from the rear main? All possible scenarios are welcome. Has anyone ever had a crate motor replaced with a new crate motor?

Installed in an 83 Chevy C10 2WD

[geezer#99]

You got a working pcv system?
Got a pic of your motor?

[kelsfine69]

I bought a 2007 GMC 2500 Duramax brand new. Front crank seal leaks a small amount right from day one. The first dealer replaced the front crank seal 3 times before they said we don't know why. I took it to another dealer and got the news that it was a porous crank. Don't know if that helps but I worked as a GM tech for 10 years myself and never heard of a that. But a new crank fixed it, Good thing it was under warranty...

A flaw in the crank where the seal rides?

[79Betty]

Nicked seal housing. Get those ALOT at work

[Ardee83]

When installed the motor the PCV system was working. the motor has only been in for about 3-4 months and only has 1,500 miles on it. I dropped the truck off at the dealership in Twin Falls yesterday so I am currently unable to check the PCV system. I asked them to keep the truck and make any repairs that are needed and covered under warranty until the leak stops. 79Betty you say a nicked seal housing you literally mean, just a nick in the seal housing? That's crazy but you say its really common? I will keep everyone updated as I hear from the dealer. The service yesterday was outstanding so I hope it continues.... thanks everyone so far

[geezer#99]

Yup! You got a pcv.
Maybe your block was align honed and your crank is now undersize for the bigger bore on the rear cap.
They make oversize seals for that situation.

[Ardee83]

Well I have some crow to eat..... as of now.... the dealership called the rear main is not leaking the oil is coming from the distributor which is great.....as of now.... I'm going to put a new gasket on and clean it up make sure its not leaking anymore. If that is the issue crow has never tasted so good! I will post any new updates!

[79Betty]

That is a relief. We do yes but i personally think it's from people... I think it's from how they ship them... We're pretty rough on em.