2JZGTE Strangest boost leak ever. Is this bad?
#16
Lead Lap
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Same results with valve cover and PCV hose disconnected and plugged. I'm going to do a compression test next. If compression comes back good then it's got to be somewhat normal. Right? Ali, I get what you are saying I'm just having a hard time understanding how it could hold boost perfectly if air can escape through the oil return. Will this not happen when it's running, but only at rest?
#17
Lexus Champion
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No, it doesn't behave the same way when running. When its running, there will be vacuum, or "0" at the hose running from the valve cover to the turbo intake piping. The PCV will be shut in boost conditions, so no boost will feed in from there. At that point, it is pretty much just ring blowby getting to the crankcase, but that vc hose will allow the pressure a place to escape and equalize.
#18
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Same results with valve cover and PCV hose disconnected and plugged. I'm going to do a compression test next. If compression comes back good then it's got to be somewhat normal. Right? Ali, I get what you are saying I'm just having a hard time understanding how it could hold boost perfectly if air can escape through the oil return. Will this not happen when it's running, but only at rest?
normally the crank case should be run to the turbo intake pipe which never sees boost, so pressure can't build up in the crank case from the turbo boosting and even if it does (internally past rings/ turbo seals? etc.) it will escape through that cc fitting. you should never plug the cc fitting on the valvecover, if you do even the slightest leak could allow pressure to build up in the crank case and give your symptoms.
the problem is with your can method is you may be putting in the psi before the turbo, so the crank case fitting will now see boost which it isn't supposed to do before the turbo.
so ideally, you need to remove the crank case hose and plug the intake side, but leave the valvecover side open to the air to vent off any pressure. you can also leave the pcv connected to the intake manifold, it will shut under boost 100%. this way if you are still experiencing any leaks at the return with the crank case open, something is leaking significantly.
If the engine is running fine I wouldn't be concerned if its not leaking anything while running. if the crank case was pressurized while running it will 100% leak oil out of the return line fitting you are saying leaks when you pressure test the system.
#19
Lead Lap
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Thank you everyone for your help. I've got good compression across all cylinders and have finally gotten sequential operating. Car feels really good with a minor caveat (starting a new thread on this).
I don't think the "boost leak" I found is an issue on a running engine.
I don't think the "boost leak" I found is an issue on a running engine.
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