Guest bastaad525 Posted December 19, 2003 Share Posted December 19, 2003 Just had a few questions about the details of the PCV system on the L28ET motor. First thing I'm trying to figure out is this... does air flow thru both the block and the valve cover, like from one to the other, or are they 'blocked off' from each other... in other words, can air from the block escape out thru the valve cover breather? On the flip side of that... I was told many times that air that comes in thru the valve cover can definately go thru the block... For instance, if you leave the hose hooked up from the block to the PCV valve, and were to disconnect the hose from the valve cover (but of course plug the end of the hose that goes to the intake boot between the AFM and turbo) that air could get sucked in thru the valve breather, thru the block and PCV valve into the intake, creating a vacuum leak. I really want to clarify exacly how all this stuff is connected. The reason this has come up is that I've recently discovered that apparently both the front and rear main seals, as well as the oil pan gasket on my turbo motor, have all started to leak. They were all newly replaced not more than 3 mos ago. Someone suggested to me that a clogged PCV system could result in pressure build up in the block from blowby, and could cause the seals to start leaking. The catch is, I am not running the PCV system at all, rather, I have both the block breather and valve cover breathers open to atmosphere. So I would think pressure in the block would not be an issue, though it is by far the best explanation for my suddenly leaking seals. However, there was an issue that came to mind. On the valve cover I have one of those little K&N filters, but the crank breather I had just left open for quite some time. About a month ago I became concerned about dirt getting into the block this way (dont ask me why it took me that long to think of that) but being a broke bastard, I couldn't go get another little K&N to put on there, so instead I took one of those blue shop towels and clamped a section over the end of that breather. I figured that would work as good as the K&N and left it at that. About two weeks ago I happened to take a look at my makeshift filter and of course the thing was drenched in oil... I figure it may have been clogged enough that it couldn't breathe very well at all. So I would think this COULD have caused excess pressure to build up in the block, except for the fact that the valve cover is still open and that filter is fine, not clogged at all... so if I got blowby and resultant buildup in pressure in the block, couldn't it still escape from the open valve cover breather? As further example, a while ago I posted another thread regarding a possible alternative routing of the two breathers. I had noticed that I got more exhaust smell in the car with the breathers being open to atmosphere, but unfortunately, rehooking up the PCV system was not an easy option for me given I had swapped intake manifolds. So I had asked if I could keep the hose in place from the valve cover to the intake/AFM to turbo boot, and just plug the block breather tube, to which I got replies that this would work fine, that it would not cause any sort of vacuum leak or unmetered air to enter the intake, and I also assume this is an indication that any excess pressure that would build up in the block could vent out thru the valve cover and get sucked into the intake. Bottom line is... would a clogged or plugged block breather tube cause excess pressure to build up in the block, causing my main seals to blow out as they have done, but given the fact that the valve cover breather is open and breathing just fine. Or do I need to look somewhere else for the cause. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 19, 2003 Share Posted December 19, 2003 The valve cover and block vent both go to the air cleaner on a carbed Z, they don't need to be "connected" to allow the air to circulate. A blocked PCV will blow seals for sure. If you think yours is blocked, fix it then see if you still have leaky seals. I don't think the block vent would be likely to clog with dirt, seeing as it always has pressure, not vacuum, and dirt isn't likely to get in there. A K&N is a good idea, though, just to be sure. Definitely take the blue shop towel off the block vent and clean the motor and see if it is still leaking. The vent at the valve cover is baffled and I don't know if it would allow pressure to escape fast enough to prevent the seals from leaking due to pressure. When I worked for Volvo, we used to see B23 motors covered in oil all the time. We replaced the PCV and the valve cover gaskets and oil cap seal, and the rest of the seals would be ok. Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 19, 2003 Share Posted December 19, 2003 So you think I may get lucky here? I mean, if it IS pressure in the block causing the problem, and I get rid of that pressure (putting a proper K&N filter on the block breather or just leaving it open again) my main seals may stop leaking? You are giving me hope and a reason not to be so upset anymore I'll pick up a K&N today and put it on the block vent and spray the motor off again when I get a chance... I'm hoping for the best and expecting the worst Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 19, 2003 Share Posted December 19, 2003 Just clean it and leave it open and see what happens. You won't be using the K&N when you route the PCV to the exhaust, right??? Good luck. Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 20, 2003 Share Posted December 20, 2003 Just clean it and leave it open and see what happens. You won't be using the K&N when you route the PCV to the exhaust' date=' right??? Good luck. Jon[/quote'] Well I went down and checked it and sure enough it was clogged BADLY... I pulled the little towel off and tried to blow thru it with a straw... wasn't happenin... I can imagine how the engine felt So that IS most likely what was happening... like you said... it just wasn't able to bleed the pressure off fast enough so when running on boost enough built up in the block to blow out the seals and gasket. Anyways I went down and got a little K&N like I shoulda done ages ago and put it on there... I feel so friggin stupid... such a dumb little mistake that will possibly cost me so much. Anyone else here ever have issues with blocked PCV valves on a turbo car cause leaky seals?? Did remedying the blocked valve cause the seals to stop leaking? I know I'll find out for myself either way... I guess just trying to gauge my odds. *crossing fingers* Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted December 20, 2003 Share Posted December 20, 2003 dude, a K&N on there is not going to make one bit of difference. did your blue rag make a diff? No. if it got clogged it was clogged from the inside not from stuff on the outside. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 21, 2003 Share Posted December 21, 2003 no dude TRUST me it got clogged BECAUSE I put the rag on there. The rag completely covered the opening, and just got soaked with oil way quick, because it's only one layer... less than a square inch of area to get soaked thru. The K&N must be like four or five times that much area, plus... well I dont know how to put this in words... but... the filter is round... now when oil comes out of there it tends to go down... gravity and such so while oil WILL soak into the part of the filter facing down, the uppermost parts SHOULD stay unclogged and free breathing, I know that is the case with the one on the valve cover thus far... With my stupid idea of just putting one later of shop towel over the opening it had no place to go. BUT just in case I will keep a VERY close eye on it for a while and be sure than the K&N wont be any kind of restriction... if it does I'll just run it open but I REALLY hate that idea. Another reason the K&N will work better is that the shop towel is really dense material... even when clean it's hard to blow air thru it... the K&N is a nice loose weave it should have no problems venting whatever pressure builds up in the block... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 21, 2003 Share Posted December 21, 2003 Did you clean out the pipe when you rebuilt the engine? If so, I'd say its odd that it would be plugged so quickly. What is plugging it? Carbon, dirt, what? Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 22, 2003 Share Posted December 22, 2003 Did you clean out the pipe when you rebuilt the engine? If so' date=' I'd say its odd that it would be plugged so quickly. What is plugging it? Carbon, dirt, what? Jon[/quote'] Yes we did. It wasn't the pipe itself that got plugged, rather, it was the paper shop towel I had used to cover the opening of the pipe... I intended it just as a makeshift filter to keep dirt from getting into the vent, but blowby from the block soaked the shop towel in oil to the point that you just couldn't pass any air thru it. It was a stupid idea that I wouldn't have done if I'd put more thought into it. I've never run w/o the PCV system before, and never run a turbo motor before... never occured to me that this thing was gonna clog and that the boost pressure in the block would have nowhere else to go 'cept out the seals. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 22, 2003 Share Posted December 22, 2003 OK, I was thinking the whole tube was packed with crap. Have you been able to tell if it has stopped yet? Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 22, 2003 Share Posted December 22, 2003 No I haven't driven the car for two days I parked it on Saturday after getting home and feeling incredibly sick and dizzy from a mix of exhaust and fuel fumes in the car... haven't really had a chance to do much about it but will tinker with it today. I found a small leak in one of the hoses that goes from the fuel to the little vent tank... All the details are on one of my other threads on this section of the forum. For a while fumes of any kind had ceased to be a problem... over the last couple weeks the exhaust smell has come back and getting worse and worse... dont know why nothing has changed that I can tell. The fuel smell just started on friday and was the final straw. Anyways... I still have high hopes and am keeping my fingers crossed that the seals will have stopped leaking. Quote Link to comment Share on other sites More sharing options...
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