Oil Leak only under boost?
Thread Starter
On The Tree
Joined: Jul 2013
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From: Augusta, GA
Oil Leak only under boost? I have a 03 Z06 with an LSA in place of the LS6. The turbo kit worked fine with the LS6 but I only ran 7 psi, now Im running 14 psi. The engine is new with only 1500 miles on it. So anyway, it will run all day long without any oil leaking out, but when I run it hard - maybe over 10 psi, oil mysteriously starts leaking from the lower bell housing /clutch inspection cover. I took the cover off and I couldn't see any evidence of a leak from the rear main, but I don't know where else the oil can be coming from. I though maybe the dipstick but it's dry.
So the one thing I do notice is that the motor seems to have a lot of vacuum at the valve covers, which explains why it blew the "press in" oil cap off my Proform Valve Cover. I have since modified the stock oil cap to fit the valve cover so I don't have that issue anymore. My theory is that the motor is not venting enough under boost and is blowing oil past the rear main. I do not have catch can but Im thinking a vented one might be the fix.
Any thoughts or advice would be much appreciated.
So the one thing I do notice is that the motor seems to have a lot of vacuum at the valve covers, which explains why it blew the "press in" oil cap off my Proform Valve Cover. I have since modified the stock oil cap to fit the valve cover so I don't have that issue anymore. My theory is that the motor is not venting enough under boost and is blowing oil past the rear main. I do not have catch can but Im thinking a vented one might be the fix.
Any thoughts or advice would be much appreciated.
Thread Starter
On The Tree
Joined: Jul 2013
Posts: 132
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From: Augusta, GA
Sort of, I have the solenoid valve in between the hose and the throttle body and there is a one way check valve also that is in the hose. It's the STS setup, been meaning to do away with that.
Thread Starter
On The Tree
Joined: Jul 2013
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From: Augusta, GA
Yeah, was thinking about doing that as well. Did some digging and it looks like blowing oil out the rear main is kind of common if the crankcase isn't vented right. And apparently the STS setup is only enough to handle low boost.
9 Second Club
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From: Joliet,IL and Las Vegas 50/50
Had the same thing op. I vented the oil cap using something like this and no longer have oil pushing while in boost.
http://www.ebay.com/itm/Trans-Am-GTO-G8-Billet-Valve-Cover-Breather-Assembly-LS1-LS2-LS6-LS3-LS7-V8-/371082140487?pt=Motors_Car_Truck_Parts_Accessories&hash=item5666381b47&vxp=mtr
http://www.ebay.com/itm/Trans-Am-GTO-G8-Billet-Valve-Cover-Breather-Assembly-LS1-LS2-LS6-LS3-LS7-V8-/371082140487?pt=Motors_Car_Truck_Parts_Accessories&hash=item5666381b47&vxp=mtr
Thread Starter
On The Tree
Joined: Jul 2013
Posts: 132
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From: Augusta, GA
Yeah that was my first thought, I found this diagram for the proper setup for high boost so I might try that. Supposed to go to the track this weekend so maybe I can just runt with the oil cap off without blowing out it.
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Yep, just having a solenoid and check valve under boost won't allow crank case pressure to vent properly under boost. The extra blow-by caused by the boost is pressurizing the crank case and pushing oil past the seals. Get rid of that and run a catch can or reroute the pcv to the turbo inlet if you'd like to do it that way. If it were me - I'd just run a catch can setup and call it a day.
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From: Joliet,IL and Las Vegas 50/50
FWIW, that is the setup I have for my PCV along with running a filter off my oil cap. Seems to be working well for me and i'm using the stock ports on the valve covers to dual saiku michi catch cans.
