Instant Rear Main Seal Leak. Why?

[HighMileage]

My GN never leaked a drop of oil until a new 60mm was put on yesterday. Now it leaks 1 drop every 5 seconds at idle,right out of the dust cover hole.

The factory breather behind the turbo (valve cover to turbo inlet) was replaced with a push in/air filter looking one.

I have the stock valve covers. Stock oil filler neck breather.

Is it possible I created too much crankcase pressure and blew the seal? Boost is set at 22psi.

Thanks!

 

[Dave Dunbar]

Was the dust cap in the oil return hole in the turbo removed before installation?


Posted from the TurboBuick.Com mobile app

 

[HighMileage]

Yes. All of the dust caps were removed from the turbo.

I'm thinking that crankcase pressure isn't escaping fast enough under boost.

I see some GN's with big hoses coming out of the top of their valve covers to large catch cans with filters on top. That's what has me wondering if my stock vent system is adequate.

 

[Nigel]

Steve, do you still have the stock rear main and have you checked the PCV valve. I also have seen oil come from other locations on the back of the motor (valve cover, intake) run down and wind up on the T/C dust cover as a drip, not one every 5 seconds though. Replacing the rope seal is a good idea if you have not already. Can be a PIA depending on the condition of the rope.

 

[HighMileage]

My engine is unopened except for valve springs.

I replaced the PCV a few years go. Valve cover gaskets a few months ago. Its still dry around them.

Yeah,1 drop every 5 seconds. Pretty disheartening to happen suddenly as I've always looked for leaks. I even put fresh cardboard under it. Now I need a sheet pan.

Hopefully this issue doesn't reoccur and keep me from running this at the track before the season ends.

Thanks for the reply,Nigel.

 

[Nigel]

Steve, in the short term you can get an inline check valve or I run the RJC PCV(some don't like it, but my car idles fine with it). That will help. I plan to be at the track Wednesday, may have to travel for work though not sure if that is required yet. Bruce.

 

[TurboBuRick]

Where is the oil line on the dipstick?

 

[HighMileage]

Where is the oil line on the dipstick?

I sure had better check that now.

Usually I don't run it with the oil to the Full mark. I keep it at 3/4.

I'm very mindful not to overfill,even by just a little. Even on my other cars,lawn equipment,etc.

Am I wrong to think that increased blowby from the new turbo blew out the rear seal?

I've done rear main seals in cars in the past. I found that its a case of excessive bearing clearance that causes the crank to wiggle,making it hard for the seal to seal.

Hopefully that's not my scenario.

 

[Pronto]

The stock oil filler is not a vent. If you don't have a filter on it the one on the v/c may not be enough.

 

[HighMileage]

The stock oil filler is not a vent. If you don't have a filter on it the one on the v/c may not be enough.

You're right. In looking at the filler cap closely,it is just that. A cap.

So,the only vent I have is the tiny KN on the front of the right side valve cover.

So now I have to look for additional ways to vent. I don't want to replace the seal only to blow it out again.

Thanks for the replies.

 

[Pronto]

Get a vented v/c cap and see if the leak slows down.

 

[TurboBuRick]

I find running the oil level a little low cuts way down on the rear main leak. I run about half way in the cross hatch.

 

[BuickMike]

IMO the only thing that is a sure fire way to stop a really main leak from crankcase pressure is a crankcase evac system. I use an ls1 electric smog pump that runs under boost. A Hobbs switch activates a relay that turns on the pump. I pull from the passenger valve cover and use the factory separator to pull through to keep oil out of the pump and it works great. I use a stock filler tube on the drivers side to the pump can pull vacuum. Jason Cramer from RJC gave me this idea.

Posted from the TurboBuick.Com mobile app

 

[HighMileage]

I find running the oil level a little low cuts way down on the rear main leak. I run about half way in the cross hatch.

I basically do the same thing. Never at Full. Usually 1/2 or barely 3/4 making sure the stick is seated.

I feel that the only way to cure this sudden leak is to replace the seal. I'm not gonna try a genie in a bottle or any treatment oil.

If its leaking 1 drop every 5 sec at idle,the seal needs to be replaced,imho.

Right now I'm at my neighborhood Mobil where they have 3 bays. I have known these guys forever,and will ask them to replace the seal. I just don't have the time or a lift. ...plus my old Snap On floor jack is leaking.

I just hope they are willing to do it. When I bring it here for NYS Inspection every year,they won't even get in it and refuse to let me leave it. "We don't want to be responsible for that."

So we will see. They are my only local alternative.

Thanks again for your advice,Rick. ...and I remember when you helped me out with this cars issues when I bought it over 4 years ago. That's when I knew *nothing* about these cars.

I appreciate your help.