Guest Tim78zt Posted August 16, 2002 Share Posted August 16, 2002 Hi guys! Just to recap...I still have the blowby coming out of the valve cover vent, which opens to the atmosphere. I wrote about this a while back and there wasn't enough info to conclude anything back then. Some said blown engine, broken rings, etc. So here is what I've done: Leakdown test...shows 5% or less leakdown in all cylinders. Compression test...checks out good all the way across. No smoke from tailpipe. PCV valve not clogged. There is almost always blowby, even without boost. It is less noticeable during light cruising speeds. So what do you think? Valve guide seals? Crankcase somehow pressurizing? Clogged vent pipe from PCV to engine block? Failed oil rings on pistons? This blowby did seem to happen suddenly when it first began about 10 months ago. Like one day it was not there, next day it was. It has not gotten any worse, but it does produce a grayish gunky mud that I catch in the catch can you guys recommended to me. Tim78zt Quote Link to comment Share on other sites More sharing options...
jeffp Posted August 16, 2002 Share Posted August 16, 2002 If you aregetting a gray matter like substance, there is only one way that can be made. Water in the oil will turn it grey so check to make sure you dont have water leaking into the cylinders, or the oiling system some way. The key here is the gray, that means water and oil are getting mixed somehow. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 17, 2002 Share Posted August 17, 2002 Was their anything that happened that you can recall that could have caused a problem? ie, over heat, bad gas and detonation. I have all my vents plumbed back into the intake tract since I don't like the smell, and it is supposed to make the engine internals stay cleaner longer. What does the underside of you oil cap look like? What about your oil? Do you see any oil in the antifreeze? White smoke from the exhaust? I would only use the Nissan gasket or the HKS one on a turbo engine. I am currently using the nissan gasket, and it has done a great job for me. If you change the head gasket, be sure to have the head checked for warpage. Sounds like Jeff has nailed you problem. Good luck with the repair. Quote Link to comment Share on other sites More sharing options...
Guest Tim78zt Posted August 19, 2002 Share Posted August 19, 2002 Lock, it's never over-heated and I always use 93 oct Mobil or Chevron. Oil cap is clean, oil is clear, exhaust does not smoke any color, no fluids mixing in radiator or crankcase. Right now it has a Nissan gasket and the block is o-ringed. Sure seems like the crankcase is getting pressurized and pushing the vapor thru the path of least resistance. Someone suggested that the crankcase vent was plugged because the vapor begins billowing within about 30 seconds of startup. To check that I have to drop the oil pan. I changed the oil last week so I'll wait till next oil change to do that. Thanks for the tips, guys! I'll double-check everything y'all have mentioned. Tim78zt Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 19, 2002 Share Posted August 19, 2002 Well I would say and o-ringed block pretty much would rule out a blown headgasket, unless there is major head warpage. What kind of rings did you run? The oil control rings I used in my engine had a fairly wide gap on the little flat rings that go above and below the wavy part. I recall being concerned about it, but I have never seen anything where someone has given a spec on ring end gap for those little thin deals. Also what kind of headwork did you have done? I have never replaced valve guides, but I usually always replace valve stem seals. I don't know how oil could get into the valve guide area except past the valve stem seals. Even if you had new ones installed, a small burr on one valve could make a hole where oil could get by. I got Beck Arnley seals from Advance Auto Parts online, and they are shorter than the one's I took off the P79 head I set up last week. Don't know if they are any good yet, but when I ring the engine and get it back together I will report in on them. They were nice and soft though, unlike the one's I took off. If you are not smoking and using oil, you could always just run a line from the valve cover into the hose in front of the turbo and make it go away. Know what is funny, the engine in my 260 has a major smoking problem, yet I have no blow by out of the valve cover. I have it out of the tube on the side of the block though. Of course that is plumbed in. I also know my compression is low on the back two cylinders. Go figure that one out. Good luck figuring it out. Quote Link to comment Share on other sites More sharing options...
Guest Tim78zt Posted August 19, 2002 Share Posted August 19, 2002 LJ, I looked back thru all the receipts for the buildup and I can't find where I was ever charged for rings!! So I don't know. And it's been 4.5 years since the work was done so I doubt the shop would remember. The headwork was sorta proprietary in that there was some porting done but I wasn't told by who (it was sent out...not in-house) or what they did. Also a valve job and cut down valve guides. I wasn't charged for valve guide seals either, so it is really possible they overlooked replacing them when it all went together. I have revved this thing pretty hard in the past so it's possible the valve guide seals blew out?? The head was shaved .080 and clamped with an ARP stud kit. That tube on the side of your block eventually makes it's way thru a mesh screen and leads to the oil pan. There should be a small cover held on with 2 6mm screws that holds that wire mesh. Mabe the cover is loose or missing. Thanks again!! Tim78zt Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 19, 2002 Share Posted August 19, 2002 Well if you have 4.5 years on the engine, that could explain your blowby issue too. I mean yes you have good compression and leak down is good also, but you could have a little wear in there. If it was me, I would plumb the top of the cover back infront of the turbo and drive it. My turbo engine uses oil, always has, but it has forged pistons and I flog the mess out of it at the track. I have about the same amount of time on mine, and plan on freshening it in a couple of years. I guess I could go with JE's next time and get a tighter cylinder wall clearance. I don't know what else to check. Good luck from here. Quote Link to comment Share on other sites More sharing options...
Guest Tim78zt Posted August 19, 2002 Share Posted August 19, 2002 by in front of the turbo do you mean the intake/throttle body? What happens to all that gunk? Doesn't look like something that would burn. Thanks again for the help!!! Tim Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 20, 2002 Share Posted August 20, 2002 In front of the turbo. The stuff gets sucked up and run through the system. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted August 21, 2002 Share Posted August 21, 2002 Tim, Do you think it could be the seals on the turbo itself? I've had that happen before the seals go bad and the oil seeps past into the intake track while in vaccum. Most of the oil gets caught up in the intercooler but, during boost it gets pushed in. You might pull some of your intake pluming and take a look at the pipes to see if you have any oil in them. Quote Link to comment Share on other sites More sharing options...
Guest Tim78zt Posted August 21, 2002 Share Posted August 21, 2002 Gosh Cody, you'd hope it wouldn't be that!! The turbo only has about 3 years of wear always using Amsoil synthetic. Would a failed turbo seal cause vapor to be pushed out thru the valve cover vent? Please give more detail on the route the vapor would be taking for this to happen. I don't understand the path the oil is taking to get from the seal to the valve cover vent all that well. On a side note, do you hang out at Alamo very often? They built my motor so I was trying to contact someone there who might answer my question without getting defensive about the valve guide seal issue. Tim78zt Quote Link to comment Share on other sites More sharing options...
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