Guest bastaad525 Posted January 20, 2004 Share Posted January 20, 2004 Okay... I"m not panicking about this (yet) but, rather just trying to get some ideas on this. As many of you know, I've gone thru hell with this turbo motor from day one of the install... and in the course of ironing out the many, large problems I ended up rebuilding the engine.... well a 75% rebuild, the head was fully done at a shop, whereas me and a friend of mine 'freshened' the block ourselves after the motor started burning oil and smoking profusely (which happened right after I had had the head rebuilt and reinstalled). We replaced all the rings and bearings (new valve stem seals were also installed). After that, the smoking had completely stopped so far as I had seen. Now... I think four months later, and with no more than 2,000 miles on the block, I have recently noticed a little smoke here and there, coming from the exhaust. At idle, a tiny bit will sometimes come out, never constantly, just a puff... I'd say this happens like 5% or 10% of the times that I have looked (which is often), and seems more common after just starting the motor, though does NOT seem particular to whether the motor is warm or cold. My wife followed me home from Tim240z's house today and kept an eye on my exhaust to see what it's doing when on the move. During normal, relaxed driving, she saw absolutely no smoke at all. If I went WOT, she would also see no smoke for as long as I was holding the throttle... the only time she would see a puff of smoke, and this was consistent, happening almost every time, is during a shift, ONLY durning a WOT acceleration pull. For each shift she would see a small puff of what she describes as light bluish grey smoke. That's it, only during shifts or actually any time I suddenly let completely off the throttle after holding WOT. The small, rarely occuring puffs I've seen at idle have also looked like oil smoke. I have checked my plugs and found NO oil on any of them, though they do look a little sooty, and I know from my dyno run last month that I do run pretty rich (10:1 A/F ratio) on boost in the midrange and then leans out above 4500 or so. Which reminds me, all the times I had her watching me doing little WOT pulls on the freeway, and that she observed smoke coming from the exhaust, I wasn't holding WOT into very high RPMS, usually shifting in the 4k range. On the other end of that, I did have her watch once as I took off from a stoplight and took it all the way up to 5500 before shifting, and she saw NO smoke at all, not during the takeoff, between shifts or when I let off. There is almost no play in the turbo shaft, though there is some oil residue in the J-pipe when I remove it (I believe it is a normal amount). When I recently checked compression I got about 120 psi, very very close and consistent across all six cylinders. I will also say that my meter has consistently read low on every engine I've tested, it's a cheap no-name unit, I estimate it is probably closer to 130-140psi. Personaly, I suspect the turbo seal may be leaking oil on the exhaust side... with new rings and valve seals, even, good compression, and no sign of oil on the spark plugs this makes the most sense to me. However, three things do make me suspect it may be the rings again. #1. my friend who helped me 'refresh' the block recently revealed to me that he did NOT hone the cylinder walls as I had thought he had done, rather, he said they looked VERY good when he got the pistons out and didn't feel it needed it. #2 he also mentioned that the brand of piston rings he bought was Rock, which, frankly, I've never heard of that brand, and that worries me as to their quality. #3 I have observed blowby smoke coming from the valve cover breather quite a few times, though I can't say it was or was not an excessive amount. Anyways... a leakdown test is up on my list of things to do at some point, and I know that will be probably one of the best ways to re-find the condition of the engine... was just wondering what you guys' first impression was as to what the cause of this new smoking problem would most likely be? Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted January 20, 2004 Share Posted January 20, 2004 I am curious if there would be a way to put an oil additive into the oil in a spot where it would first have to go through the turbo, and not the engine. If you could do this, I am pretty sure there are additives that will make a very unusual smell at the point that they blow out the exhaust. Then you could tell (based on when the smell comes through the exhaust) if it is from the turbo seal, or elsewhere. Do you have a working oil pressure gauge? I think I remember you saying before that you dont trust your gauge. Maybe you are building up too much oil pressure? What grade oil are you running? Do you have a high-quality high-flow oil filter? Any way that you could take the turbo off and secure an old bicycle innertube to it to pressurize the oil inside to see if the seal leaks? Quote Link to comment Share on other sites More sharing options...
fl327 Posted January 20, 2004 Share Posted January 20, 2004 pull the jpipe off and see how wet or dry the turbo output is. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 20, 2004 Share Posted January 20, 2004 DOH I knew I forgot to put some info in that post, thanks Nic... I'm running Mobil 1 10-w30 oil, and broke the engine in with Castrol non synthetic straight 30w. I'm running a Mobil 1 oil filter, which, considering it's cost ($13!!!) I have to believe it must be a good filter... my next oil change though I will hunt down a Wix filter since so many seem to swear by them. My oil pressure gauge reads about 1/3 of the way up at idle, and varies between there and up to maybe 5/8 of the way up while I'm driving around. I have no idea how I could use some additive the way you describe... I may be able to try that bicycle pump trick though. I'm curious, can a turbo be leaking oil even if the shaft has next to zero play? I mean this thing feels like it is brand new.... Quote Link to comment Share on other sites More sharing options...
fl327 Posted January 20, 2004 Share Posted January 20, 2004 I wouldnt rule out a leak from the turbo. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 21, 2004 Share Posted January 21, 2004 nah, not ruling it out, rather, I'm almost sure that's what it has to be... figure everthing else has been fixed already... that's pretty much the only thing left. Okay but I have a question, if the turbo shaft seems fine, or the bushing or whatever it is that causes there to be excessive play in the shaft (which in this case there is not) what else can go bad that would cause oil to leak from the turbo? The turbo output and the whole J-pipe have a light film of oil thruout, but from what I gather it is not more than what is considered a normal amount. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 21, 2004 Share Posted January 21, 2004 Anyone else? Just wondering if the symptoms I describe are typical to one specific problem... or more specifically, if the pattern I describe seems a likely indicator of bad rings or valve seals or sounds more like the turbo? Quote Link to comment Share on other sites More sharing options...
Guest znow white Posted January 22, 2004 Share Posted January 22, 2004 I was also wondering about that...if a shaft can have no axle play I believe it could still break a seal to cause an oil leak. Thats what happened on mine... the shaft doesnt have allot of play but the jpipe is full of oil.... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 22, 2004 Share Posted January 22, 2004 but can anyone confirm if the symptoms make more sense to be the turbo? I find it odd that it really only smokes pretty much between shifts, and there is no oil on the plugs at all. Quote Link to comment Share on other sites More sharing options...
fl327 Posted January 22, 2004 Share Posted January 22, 2004 adjust the valves first and see if it still smokes. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 22, 2004 Share Posted January 22, 2004 Valves being out of adjustment can cause smoke? I know for a fact mine are a little out... a bit of tapping going on there... I give up trying to adjust them myself... even the last time I did it, I was very confident, and did it in like 20 mins, engine hot, and was CERTAIN I had gotten it just right, and yet still it taps. After that I gave up. If you think that could be a cause I'll get my friend to adjust them... he always seems to get it right. Quote Link to comment Share on other sites More sharing options...
technicalninja Posted January 22, 2004 Share Posted January 22, 2004 I am suprised no one has brought up valve guides. If the guides are worn oil will be pulled past the stem seals during high vacuum conditions (ie when you get off throttle during gear changes- due to large number of intake strokes at 6k rpm vacuum in intake can reach 27-28 inches for a moment). This issue is common on all engines. Did your machine shop replace the guides? In 20+ years of wrenching on Zs I have all ways had to replace at minimum all of the exhaust guides and 50% of time intakes also. when both the guides and seals are bad the engine will smoke badly at start up (worse in cold weather). Replacing just seals will usually cure cold start smoke for 10-15k miles but engine will still smoke during shifts and smoke will be more prevalent during high RPM shifts. Stem seals will wear out much quicker on bad guides. If guides are in perfect shape stems seals do very little to reduce oil consumption. Nearly all early chevy V8 engines had no seals (some had a useless O-ring which rode the valve stem itself). Hope this helps-good luck Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 22, 2004 Share Posted January 22, 2004 I have the same problem with my engine, and suspected the turbo due to oil in the compressor housing. I replaced the turbo, and still have it. Now with a blown head gasket, I am going to have the head worked, and ALL the valve guides replaced. I talked with a guy at Rebello, and he says the turbo engines routinely have to have exhaust valve guides replaced, hardly ever on the intake. So that is what I am going to do. I have good compression, no smoke except when boosting and then shift gears. If the guides don't solve it, then the turbo is going to FP for a rebuild and compressor upgrade, and if that doesn't work, then the engine is coming out. I got no oil anywhere right now. No intake, PCV, none dripping from the turbo that I can find. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 22, 2004 Share Posted January 22, 2004 I am suprised no one has brought up valve guides. If the guides are worn oil will be pulled past the stem seals during high vacuum conditions (ie when you get off throttle during gear changes- due to large number of intake strokes at 6k rpm vacuum in intake can reach 27-28 inches for a moment). This issue is common on all engines. Did your machine shop replace the guides? In 20+ years of wrenching on Zs I have all ways had to replace at minimum all of the exhaust guides and 50% of time intakes also.when both the guides and seals are bad the engine will smoke badly at start up (worse in cold weather). Replacing just seals will usually cure cold start smoke for 10-15k miles but engine will still smoke during shifts and smoke will be more prevalent during high RPM shifts. Stem seals will wear out much quicker on bad guides. If guides are in perfect shape stems seals do very little to reduce oil consumption. Nearly all early chevy V8 engines had no seals (some had a useless O-ring which rode the valve stem itself). Hope this helps-good luck It may be the guides then... I am not sure if the shop that rebuilt the head replaced the guides or not, as I went thru a third party. I know the seals are new, I pulled off all the rockers myself and removed the seals, they were all new. I also checked for side-to-side play of the valve stems in the guides and they were all very tight. But, your symptom description does make sense, and if that's the case I'm stuck for now. The one thing that you mention that does NOT match is that the smoke is definately LESS prevalent the higher I rev the engine. If I shift around 4000rpm, then there is a little puff, if I shift at 5000+ rpm, then nothing. I would think the higher vacuum at higher rpm would cause more smoke. I didn't know that the guides on turbo engines wore out much faster... I know the few N/A heads I've had built, replacing the guides was never an issue, or required, and never gave problems when I didn't. Just another case of turbo motors needing too much damn maintanence Lockjaw keep me informed if replacing the guides solves your problem... Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 22, 2004 Share Posted January 22, 2004 will do, but I hope you aren't in a hurry, I have't turned the first wrench yet. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 24, 2004 Share Posted January 24, 2004 doh anyone else with fl327? On thinking that possibly misadjusted valves may have something to do with it? As I said I give up trying to do them myself... one of those things I just can't seem to get right. I can pay a friend like $30 to do it... I know I probably should do this anyways but just wondering if it would have anything to do with the smoking? Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted January 24, 2004 Share Posted January 24, 2004 I can't see how... My bets the guides. Quote Link to comment Share on other sites More sharing options...
twoeightythreez Posted January 7, 2007 Share Posted January 7, 2007 Mine (L28ET) doesn't smoke at cold start, but starts smoking heavily 10min after startup. Compression ranges from 160-170 across (which seems high for turbo motor but...) If I drive the car the smoke seems to dissipate, and it's fine until I let it idle for awhile again, and then I carpet the rear with smoke. If I pull the hose off the valve cover (I still have this going to the intake thru a 2nd PCV valve, and it seems to be working, admitting vacuum but blocking boost) while the engine is smoking there is no smoke puffing out of the valve cover. The turbo outlet has no oil film on it. I don't get it. ANybody have ideas? Is it possible for a turbo seal to leak only into the exhaust when the car is sitting, then just have smoke as the exhaust heats up? I'm at a loss here. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted January 7, 2007 Share Posted January 7, 2007 Check your PVC... might be clogged.. too much POSITIVE pressure in the block.. so much the oil is not draining down the oil line into the oil pan.. so its backed up.. has no where to go but OUT.... this will get oil in the compressor and intake piping.. as well as oil in the exhuast which burns and creates smoke notice it only smokes when WARMED UP!? well when its cold.. the oil is dripping into the exhuast but doesnt burn because its cold. then the exhuast heats up then you have smoke how do I know? ive had this issue.. i eventually just ran an OPEN setup with a mesh screen.. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted January 7, 2007 Share Posted January 7, 2007 LOL... Guys, did you guys notice that the last post was January 2004? Quote Link to comment Share on other sites More sharing options...
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