zboi Posted December 23, 2023 Share Posted December 23, 2023 I'm experiencing some high crankcase pressure when in boost, to the point where I have oil coming from the dipstick (seal on that is worn out so I can maybe fix that) and also also shooting like a jet out of the timing cover to cylinder head junction. The timing chain to cylinder head junction is due to the head gasket having torn there. Now I'm not 100% as I haven't been able to look at the leak under boost, but the aftermath is oil getting all the way to the firewall and shock towers with oil puddles at that gasket junction, so I'm suspecting there is some high pressure involved. My current PCV is the factory block tube to manifold, PCV valve seems to work fine from the me blowing in it test, and then a valve cover breather. I see people recommending instead of the breather going to the air filter, but I just have a cone filter directly on the turbo, and not sure how I would achieve that. Is there any other advice how to remedy this? I really really don't want to pull the head to replace that gasket, and it does not leak at all while not under boost (plus this would just make the next weakest link leak. I'm surprised that the pressure isn't relieved by the valve cover breather honestly. Compression is showing pretty good 165 on 5 cylinders 175 on another, but no idea on what the mileage on this motor is. Quote Link to comment Share on other sites More sharing options...
zboi Posted December 23, 2023 Author Share Posted December 23, 2023 (edited) Probably also important, the engine is a L28, and the PCV valve is the factory one (as far as I know). I just read there is supposedly a difference in the turbo and non-turbo PCV valve. Is that true? Edited December 23, 2023 by zboi Quote Link to comment Share on other sites More sharing options...
rossman Posted December 24, 2023 Share Posted December 24, 2023 Most people including myself, simply plumb both the valve cover and block vents to a catch can. Quote Link to comment Share on other sites More sharing options...
zboi Posted December 24, 2023 Author Share Posted December 24, 2023 I just tried driving around with the block breather hose disconnected, which would be analogous of the dual vents/catch cans. Still have the leak showing up and only under boost. I'm thinking this is bad valve stem seals, I can smell the oil start to leak and burn as soon as the boost starts kicking in good. I also had the breather hose positioned where I could see it while driving, and didn't notice any crazy amount of mist or smoke. However, after doing some boosted runs I see some white smoke in the valve cover area, and it smells like burning oil. Quote Link to comment Share on other sites More sharing options...
rossman Posted December 24, 2023 Share Posted December 24, 2023 Seems like you'd have oil burning out the exhaust, especially just after a cold start if your valve stem seals are bad. You could try retorquing your head bolts in case your problem is a head gasket leak into the crankcase. Quote Link to comment Share on other sites More sharing options...
zboi Posted December 24, 2023 Author Share Posted December 24, 2023 Yep I got smoke on cold starts, and the car is hard to start after sitting. Also seen oil on spark plug threads. I had gotten a felpro gasket set for the timing chain job I did, so may as well pull the head and replace all those seals. It will at the very least stop the oil from getting all over the engine bay and onto my header. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted December 26, 2023 Share Posted December 26, 2023 My buddy had his cone filter behind the headlight bucket with piping bent appropriately and through the inner fender and the valve cover hose tapped in after the air filter... Quote Link to comment Share on other sites More sharing options...
evildky Posted December 26, 2023 Share Posted December 26, 2023 Your blowby cant get out because the manifold is pressurized, thereby pressurizing your crankcase. Your block vent should either go before the turbo, which would mean making some sort of adapter between your filter and the turbo or route it to a catch can. Quote Link to comment Share on other sites More sharing options...
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