Hello all, I have a 1995 jeep xj 4.0 turbo with a newly rebuilt forged engine. I am going to run 20psi but as I am still tuning I have my wg set at 13psi. My problem is that under boost my rear main seal pours out oil. The engine can idle all day and not leak a drop. I currently have 2 breather ports on my valve cover (without check valve thing) going to a three port catch can (middle port is ran on my turbo inlet pipe after air filter. (3/8 hoses). I know this system is somewhat helping because there is junk oil stuff in the can.

A little back story:

I blew up my stock 225k mile stock engine on 14psi (no idea why... lol)
I than rebuilt the engine with hypereutectic pistons .030 over and had the head machined and I opened the combustion chamber by porting the head to lower cr.
I was using a chinesium turbo that blew apart in a week and pieces made it through my tmic and held my valve open and put a hole in a piston.

Please don’t use Chinese turbos, they cost way more than $80 on eBay...

I than rebuilt the engine again with DSS custom forged pistons and a 70mm garret ball bearing turbo. This time around I just rebuilt it in the car.
After firing it up and driving it, it started pouring oil out the rear main seal. I than tore it apart and installed a new rear main seal thinking that it sitting all torn apart for 4 weeks while waiting for pistons caused the seal to go dry and the crank grabbed it on startup.
Obviously this is not the case.

How can I fix this? Electric Vacuum pump on a pressure switch hooked to a second oil catch can on my oil pan? Any help is appreciated. Thank you.

 

You could try one of these, the exhaust vacuum sucks the oil out. Would be a lot cheaper than a pump.
https://www.moroso.com/crankcase-evacuation-system25900/

 

"Cannot be used on cars with mufflers"

 

It really sounds like you are putting the seal in backwards.
Which way do you have the lip facing?

 

Thank you for the responses. I checked everything over and I can blow air from my mouth freely back through the catch can and it comes freely out the oil dipstick when removed. I am starting to think that my leak is not pcv related.
It is impossible to install the rear main seal backwards because the main cap is machined so that the lip fits in only one way.
Any other ideas why this is happening? Thanks.

 

You are either putting pressure in the crank case or your venting is not adequate.

 

The cap seal you cant get wrong. The block side can easily be wrong.

 

Alright so I put the Jeep on the lift and boosted the engine to 12psi with my foot on the brake and oil started to leak. I also blew 40 psi from an air compressor through the catch can while the engine was running and oil leaked again. Obviously I have a crankcase vent problem. Should I add a very large vent to my oil pan or should I get an electric vacuum pump? Thank you.

 

Post a few pictures of your setup.

You are running 3/8" breather hoses?

 

Yes 3/8 hoses. I can completely bypass my catch can and I still have a ton of crank case pressure. I can post pictures tomorrow.

 

On my oil catch can this is how I set it up and haven't had any oil leak problems.
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I installed a oil catch can that the pcv fumes go through. It has two one way check valves, under no boost it sucks fumes back into the intake manifold, under boost the check valve closes and the other check valve opens sucking fumes into turbos and then into the air stream into intake manifold.

 

Bump your breather hoses and fittings up to at least 5/8 and make sure you have nice smooth transitions everywhere.

 

I got bigger hoses and it no longer leaks. Thanks.

 

Glad you fixed it, one thing that wasn't mentioned is that under boost the amount of blowby increases. So you have to account for that as well as any obvious paths

 

I've been using, and highly recommend, a turbo car PCV setup. Simply copy any factory turbo car from any manufacturer.

On my 5.3L 750hp setup I used a Supra PCV valve, right off the back valve cover tied into the intake manifold suction for the brake booster.

On the front valve cover, run a hose from the crankcase to the pre-turbo intake pipe, the pipe that the air filter is connected to. You also must run a high quality paper air filter element to achieve some pressure drop, post air filter. I used AFE paper-dry re-usable filter. Then measure crankcase pressure with a 2-bar map sensor (same way you measure boost pressure) to dial in or at least make sure you can achieve 1 to 3" Hg of vacuum on the crankcase AT ALL TIMES.

This replicates Factory PCV for any turbo car, and is ideal for daily driver and high mileage engines, useful for 200,000 or 300,000 mileage to keep oil inside the engine and pressure from blowing into oil seals.

VENTING by itself is a time bomb. When the crankcase pressure rises, since pressure is NOT a vector (it is a scalar unit) there is pressure in every orifice moving every direction simultaneously, which means for the vent to be 'working' there must also be pressure applied to every oil seal inside the engine. This will gradually lead to oil leaking, oil blowing out, and oil blowing into the baffle system which will act like a sponge/reservoir for oil to collect. Also, pressure negatively affects piston ring performance, it will increase blow-by to have pressure venting from the crankcase. Additionally, as if those two major issue aren't enough, pressure caused by blow-by gasses is able to easily enter engine oil, due to universal law of partial pressures (chemistry textbook), which will reduce engine oil life and contaminate engine parts with partially combusted hydrocarbon fragments and other blow-by related conglomerates/gasses which interact with metal materials.