This is my 4.0 build. Nothing crazy, just hobbyist testing out stuff. Ive learned a lot throughout the way. Currently i have no hoses hooked from the pcv to the manifold, they are cracked. I was thinking about getting a catch can because the damn thing spits out oil through one of the pcv´s once im giving it the beans at operating temp. There is no blow-by, i have made sure of that, aside from that the car runs like an absolute top. Surprisingly however, when i first started up the engine it was just NA, i drove it around a while to test brakes and such before driving it to the dyno, it had no leaks whatsoever. After it was tuned to run on 8 psi we beat the living **** out of that 4.0 on the dyno, and suddenly the rear main seal started to fail.... i beat the **** out of it a little more because it was fun to drive, after all that leak wasnt anything crazy, and then the dead giveaway that something was wrong in the system was when it blew the front main seal away too. What is going on? and what should i do? The front pcv which is just a hole to let out pressure, is not clogged, you can see the vapor coming out. what gives? what should i do?

NOTE : the videos are dyno pulls and the car idling if you want to check it out.

 

As you state, on these engines the PCV valve is just a small hole, doing nothing to prevent pressurized air from the turbo from bleeding into the engine block. PVC valves from other vehicles act more like a check valve when pressurized the wrong way, either by boost or a backfire.

An electric vacuum pump could also be used...

 

Could also be that the piston rings arent sealing. Looks like you just used a dingle ball hone to get some cross hatching in. What grit was it? Going to assume new rings too? Were they anything special or just stock replacements? What did you gap them to?

Also, did you block off both the breather and vent port on the valve cover or just left them open? If blocked, that will do it.

 

All engines have blow-by, boosted engines have more blow-by than NA. The whole purpose of having Positive Crankcase Ventilation (PCV) is to remove the products of blow-by in order to keep the engine and oil cleaner so they both last longer. If you ever worked on 50s vintage engines that used a drag tube venting system you will know what I mean. Those engines have accumulations of gunk that are incredible in just a few years and the engines rarely lasted over 100,000 miles.

PCV means that manifold vacuum is applied to the crankcase/valve cover. A filtered air vent is also installed to let fresh air in as the blow-by gasses are removed. The Jeep version of the PCV is just an orifice that restricts the amount vacuum applied. A real PCV is a spring loaded valve that meters the amount of vacuum applied based on the vacuum available from the intake manifold. When high vacuum is available the valve meters down by compressing the spring thus limiting the rate of air flow. When manifold vacuum is low the spring pushes the valve open allowing more air flow.

You need to have a functioning PCV on your engine. I suspect that the simple orifice type is not going to be adequate for your needs. you will probably need to adapt a real PCV into your valve cover. If your seals haven't actually blown out' but are just weeping from internal pressure, you may not need to replace them.

 

You're getting too much boost blow by past the rings...And if it's high enough to blow the RMS or any other seals that normally don't leak even a proper PCV isn't going to solve that much pressure... You need to use a zero gap style ring like total seal...In simplified terms the ends are tapered and overlap for the seal instead of a gap...That's the only way to solve your problem without spending more than it's worth...Welcome to the world of boosted engines...

 

Corky is 100% correct. Engines are airpumps and yours has a flow issue.