Guest bastaad525 Posted December 23, 2003 Share Posted December 23, 2003 You know... a thought has occured to me, and is kinda pissing me off now. I had posted how my turbo motor has suddenly decided to leak from both the front and rear main oil seals, and also from the oil pan gasket. All three units are no older than 4 mos. Some suggestions and thinking lead me to believe this was caused by a clog in my PCV system. I run both the valve cover and the crank vents open to atmosphere, I had a small K&N on the valve cover, but had used a heavy duty paper towel as a makeshift filter on the crank (had always intended to put a K&N there as well... but well you know... outta sight outta mind). The paper towel had gotten coated with oil fairly quickly, and had pretty much blocked off the crank breather completely. I was convinced that this was most likely the cause of my leaking seals, as pressurized blowlby was probably getting into the crank and not able to get out... even though the valve cover breather was breathing easily. By the way, I have since replaced the paper towel with another small K&N, and unfortunately, it has not helped the leak problem as some of us had thought/hoped it might possibly do. Then I figured... okay think about a stock PCV setup on this motor... the PCV valve itself is a one way valve that only allows air to be sucked out from the crank, into the intake. But that valve is only open, allowing the air to be sucked out of the crank, under vacuum, right? I would think it would be held closed from the intake manifold side under boost, effectively blocking the crank vent, the same way my oil soaked paper towel was doing, and leaving only one way for pressure in the crank to be released, which is thru the valve cover breather. So now I am really doubting that the clogged crank breather really was the cause of my seals leaking at all. Any one have a second oppinion on this? I mean... I know it must have been caused by something and I find it highly unlikely that the seals were installed wrong or something like that... it's kinda hard to do I would think! But it must be that, or something else... so now I'm kinda angry... you're not supposed to have this stuff happen on a newly rebuilt motor. And if it wasn't my fault after all... grrrrrrrrrrr. My other issue is... I think having both breathers open and breathing so freely now may just be the source of the exhaust smell in the car... either that or somehow it's the leaking oil getting burned but I've checked several times now and dont see any indications that the leaked oil is getting anywhere near the exhaust... just on the oil pan and straight back to the tranny. Anyways now I"m thinking of ways to reconnect everything. I may just run a hose from both valve cover and crank breathers, tee them together into one, and run that one to the stock location on the AFM-to-turbo boot... that should be fine right? I REALLY dont want to remove the intake manifold to have a hole tapped for a PCV valve and the old hole can not be used. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 23, 2003 Share Posted December 23, 2003 Bastaad, you're thinking Chevy or something. The PCV in an L series is a hole covered with some folded up screen in the side of the block. The vent on top of the valve cover is baffled. That's it. No one way valve in either case. Connecting the PCV to the intake is a fine idea, and it won't hurt anything. The only thing it will do is add oil and crap to the air fuel mixture, but that was part of the original design anyway. At least it should definitely show you whether or not those hoses are the cause of your exhaust smell. I don't think your noxious fumes are coming from the PCV though. You might get a whif, but not enough to complain about. Another cheap easy thing to do if you think that your seals are bad is to pull the front crank pulley and pull the front seal and look at it. See if it looks burnt. They were lubed before installation, right? Anyway if the front seal looks good I'd hesitate before pulling the tranny to get to the rear one. Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 23, 2003 Share Posted December 23, 2003 hmm I thought a PCV valve was there to let air thru one way but not the other? Like a check valve. I'm talking about the valve that normally bolts in on the underside of the intake manifold, and then a hose goes from the block vent to that. I thought the whole purpose of that was for it to suck blowby gases out of the block, but that it had to be one way so that air could not get pushed from a pressurized intake manifold back INTO the block? Another thing I remembered. For a long while after I first swapped to this intake manifold, I had the whole thing set up like this: I left the hose in place from the valve cover to the intake boot, and just put a plug on the block breather. I even posted a question here asking if that would be okay (it's here: http://hybridz.org/phpBB2/viewtopic.php?t=25744&highlight=breathers). Going back and reading that thread I remember that I did it that way back then for the same reason... noticeably worse/more exhaust smell in the cabin when those breathers were left open to atmosphere. The general consensus was that it was okay to block the block vent like that as long as the valve cover was not also blocked, and that having it routed that way, the suction of air from the intake boot where the valve cover is routed to, would be enough to draw any pressure out of the block, as well as any blowby. And as long as the block is sealed properly (oil cap, dipstick, etc.) it shouldn't create a vacuum leak either. I ran the car that way for a couple months with no sign of leakage from seals or oil pan gasket. Again, this is all adding up to tell me that the 'filter' I had on the block vent getting clogged up would NOT have been the cause of my seals failing. By the way... I still have the old stock PCV valve that was bolted into my stock turbo manifold, and looked at it... it did not appear as you described, rather it was a typical PCV valve (at least as 'typical' as all the ones I've seen) with a sort of floating pin in the middle that is spring loaded and can be shaken around. Definately looks like a check valve to me.... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 23, 2003 Share Posted December 23, 2003 Well, maybe I'm wrong. Wouldn't be the first time. But the original carby setup doesn't have a check valve in it that I'm aware of, and the ports that come off the valve cover and the block don't have valves in them. I guess I was thinking Chevy or Ford where the PCV valve (the check valve) is stuck straight into the valve cover. I have to admit I'm not too familiar with the L series FI setup. Never owned one, so I've never had to learn it. FWIW--those Volvos have a "flame trap" which is a copper or plastic mesh and that's it. (That I'm aware of) Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 23, 2003 Share Posted December 23, 2003 actually I was running an N/A motor with SU's on it before this motor, and it too had a one way PCV valve, bolted into the balance tube that went between the two intake manifolds. Same deal there, a hose is connected to the crankcase breather vent and runs to this PCV valve. The valve cover breather on that one just runs into the air filter housing. That still strikes me as odd... I would think that would create a vacuum leak, as air could be drawn in from the valve cover vent, thru the block and thru the PCV valve, into the balance tube, which is already PAST the SU's, and from there of course thru the intake manifolds and into the engine... hence this air would be unmetered wouldn't it? never could make sense of that..... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 24, 2003 Share Posted December 24, 2003 Well I figured out a way to route both breather vents back into the intake. It took some creative parts mixing and (mis-)matching Now both vents are routed to the rubber boot between the AFM and turbo. I figure this should work just about as well as stock... possibly even a little better?? Since there is always suction present in that boot to pull any blowby out of the engine, and under boost it should really be pulling, I imagine it might possibly have some of the 'evacuation' effect that can supposedly benefit hp? I dunno... anyways... it still hasn't helped my oil leaking problem NOR has it helped get rid of the sudden increase in exhaust smell inside the car... I'm really getting bummed about this whole thing... what an xmas present huh? I went from having my Z running 99% perfect to having it puking oil from several places and filling the car with horrid exhaust smell... and all this out of a rebuilt motor with new seals and gaskets all around. Merry F'ing Xmas........ Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 24, 2003 Share Posted December 24, 2003 Do you really want oily crap going thru the AFM? That plan seems suspect. The Bernoulli principle would keep air drawing INTO the manifold I think, even with a turbo. I think the check valve is probably there to keep backfires from igniting the compressed air/fuel/oil in the crankcase. Again, I THINK. Could also be that there isn't enough flow at low rpm to suck... Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 24, 2003 Share Posted December 24, 2003 I plumbed it in after the AFM, before the turbo. Into the stock location that the valve cover breather would go into anyways. Even if there is no suction there... that's okay the main thing is that I didn't want there to be any restriction, and I want the blowby to be recycled and burned by the engine as opposed to just pouring out into the engine bay. But I was also hoping that when on boost, when there would be the most blowby getting forced past the rings, that the suction in that pipe would be strong enough to instantly pull that blowby out and never let any pressure build up in the block. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.