When I rebuilt my engine i had a rear main seal leak. Got to a point where it was a steady stream of oil. After I removed the rear main I noticed that I lipped the seal which caused the issue. After searching the forum there were many posts on the best way to replace the seal. In my case I dropped the upper oil pan, removed the locating dowels and gently worked the seal on a slight angle to reduce the likely hood of it lipping again. Punched the dowels back in and put all back together.

I'm noticing now that I have slight leak but not sure if it is due to the added boost or the amount of oil pressure. Running about 14psi and see around 90psi oil pressure when oil is cool. (revup oil pump on non-revup)

Is it common to have a bit of oil out of the rear main on a boosted Z?

 

IMHO it shouldn't leak at all.. After tearing down my last motor with approx 15 k boosted at 10.5# i specifically checked for leakage at the rear main.. It was dry as a bone n that motor had about 80 k on it...

Plus after a while all that oil would start to give u clutch issues street a while no matter how small...

Just makes sense to me!

 

when i did mine, it leaked only when i didnt use enough RTV. You need to use more than just in the corners. the 2nd time I did it with more RTV, no leaks.

 

blew out my rear main seal 3 times. after that last time changing it... let it drip. the motor is about 7 years old now, still drips. **** it. if i ever built another VQ35DE, i would add additional PCV ventilation to attempt and cure it.

 

str8dum1 - I did use rtv across the seal as I noticed your post quite a while ago instead of the corners like the fsm says. My concern is that it is squishing past the rtv since rtv doesn't really stick to the rubber seal.

phunk - The pcv is drilled out. This goes to catch can then back to intake pipe with inline check valve. Driver side cover goes to atmosphere and both covers are still joined in the middle.

 

RTV doesn't stick to rubber?! That's a myth if I've ever heard one. Put some rtv on a dry clean piece of rubber and it's a nightmare to get it all off. It sticks quite well. I've never had a rear main leak and I always use rtv across that little rubber seal.

About your breather system. The passenger side being attached to the intake makes it pointless during boost. The boost pressure closes the check valve meaning it won't vent to the atmosphere at all. The drivers side rear port is only 1/8" diameter hole inside that large nipple. You have to drill it out to get any venting from that.

So under boost you are only venting out of a 1/8" hole. Not near enough to reduce the boost pressures in the crankcase. The middle cross over ports are the largest ports and when vented to atmosphere provides the best crankcase relief of pressure.

also, oil pressure will not affect those seals. There is no direct oil pressure on the rear main or front main. Oil will splash up on those from motion or crank windage. Crankcase gas pressures are what would force the oil out of those seals.

 

Jeff, the RTV sticks but not like its "keyed". I noticed this when I removed the oem seal and i was able to peel the rtv off the original seal.

With the breather system I was supposed to say that it goes into the turbo intake pipe. See image below

 

^ why the check valve in that setup? doesn't appear to serve any purpose except restrict flow.

 

To be honest i read through the long a$$ thread about catch cans and crankcase pressure on this forum and the above is what I ended up with. The check valve is a earls -8AN so it has a decent opening.

Does my setup help CC pressure nfi however open to suggestions.

 

You need to use more than just in the corners

 

I drilled out my pvc, drilled out driver rear vent, drilled out front center vents and everything is dumped to atmosphere with breather filters. No problems at all

 

@DiegoQuin - The RTV was across the whole seal.

I will start with enlarging the rear cover outlet but happy to try other options. All ports to the atmosphere may help but this will probably make the car smell like oily fumes.

 

ehh my car smelled like exhaust anyway so i never noticed lol

 

not sure Mr RIzk, if that passenger side vents when under boost then it should flow enough but it would be restricted by the small openings on those ports. If you have abnormally high blow by then they might not be sufficient for your exact engine then.

are you using the oem nissan rear main seal? The aftermarket ones are junk.

 

@binder

Yep new oem rear main and new oem half moon seal. Not sure if related the only other difference between most builds i have seen in the US and mine is that the piston to bore clearance is tighter on mine. Most owners I have seen use about 0.035 where mine is 0.028.

 

Hmm, less clearance I would assume should reduce blow by if it causes any effects. I don't think it would be significant though since the rings will be doing the sealing moreso than the piston walls themselves.

 

A quick update. I have now drilled out the rear drivers side port to about 10mm and also enlarged the PCV to 6mm. I hope this helps.

 

It should help a lot with crankcase venting. The unfortunate thing is if that rear seal has already been compromised then it might be damaged and continue to leak no matter what.

 

I just got my new motor in and started driving it last night to break it in. Sure enough, my mother ****ing rear main seal is leaking. I wish I would have known that was a common problem, I would have been more careful putting in the new seal. Now I have to go and pull the ****ing motor back out again. FML.

 

Least you noticed the leak before u ran out of oil. Could have been a lot worse