Nigel Posted June 15, 2002 Share Posted June 15, 2002 I have a rebuilt l28 Turbo engine in my '73 240Z. The engine has new cast Nissan pistons, perfect circle rings, Clevite 77 bearings, 1mm HKS metal head gasket, ARP fasteners all around, and complete head work. Turbo is a T3/T04 hybrid. Engine management is SDS. I've got about 50 miles on it so far, and three things that may be related have got me rather concerned. The first thing I noticed is that when I rev the engine, I see a puff of grey/blue smoke. Secondly, I checked the plugs and number 5 is wet (or, at least damp) and it smells like oil (as best I can tell with my alergies). All the others have a grey/tan color. The third thing I noticed is that the top of the number 5 piston is competely clean! All of the others have carbon deposits. Now, I've read that a rebuilt engine may smoke and oil foul plugs until it gets broken in. Is this true? And what about the fact that that piston top is completely clean? Is this what you'd expect to see with an oil fouled plug? It seems kind of strange to me, but I've never had a car with a rebuilt engine before. Out of curiosity, I did a compression test on #5 and it's two neighbours and they all came out dead even at 150. I put a timing light on the #5 plug wire and it flashes steadily, so it should be getting spark. I'm kind of wondering if that injector may be clogged (original 20 year old injectors). I did put a screwdriver to it, and it does click away nicely. Hopefully you guys will be able to reassure me that this is all normal for a fresh engine. I sure hope so, because this whole restoration project has been one problem after another and it's been draging on for years. I just want to drive the damn car! Thanks!!! Nigel Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 16, 2002 Share Posted June 16, 2002 Ok, first you only have 50 miles on it, so it is feasible that the oil control ring is not seated yet, but I kind of doubt it. You could have a leaking valve stem seal also. With a turbo engine, and a turbo, you could have lots of issues, but I would bet money on a oil control ring. I had the same thing happen to my last engine, and I was so careful, yet, I still screwed up the expander ring in the oil control set-up. You did not say what rings you have specifically. Are they chrome? If it were me, I would snatch that piston out and put a new oil control ring on it and put it back together. Not what you want to hear I bet. Good luck. Quote Link to comment Share on other sites More sharing options...
Nigel Posted June 16, 2002 Author Share Posted June 16, 2002 No, that's not what I wanted to hear. *#%@&%$%#! This can't be hapening. It just can't be! The insulator on that plug is just shiny, not dripping wet. Is it really that bad? I'm not too certain of what the rings are made of. I can't find any specifics on the Dana web site. I had to pull the rebuilt transmission yesterday because the leading edge of half the teeth on the front countershaft gear have all chipped for no good reason! I managed to slice the back of my hand open on the pressure plate while I was removing the clutch to get at the rear main seal that's leaking! I swear I could have rebuilt 5 Z's in time it's taken me to do this 1! Nigel Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 16, 2002 Share Posted June 16, 2002 My last project Z was the worst I have ever dealth with, so I feel your pain. Some of the Nissan ring packs had a fine wire that went thru the expander ring in the oil control pack, but I have not checked any lately to see.That would have saved me. I had no smoke for about 100 miles, and then all of a sudden, there it was. My next engine is going to have an 89 mm bore, and I think I am going to use 300TT rings. If it is any consolation, I have smoke now when I shift gears after building some boost. Not all the time though, so I am thinking that the turbo is going south. Good luck with the car, but I would almost be willing to bet money your oil control ring is not right. Make sure you check the valve stem seal first. When you pull the head, and the piston edges are shiny on that cylinder, that is a pretty good indication of oil control problems. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted June 16, 2002 Share Posted June 16, 2002 Just a thought guys. Could the valve stem seal on that cylinder be leaking. I would imagine that the exhaust would put out blue smoke all the time if the oil ring had crapped out. If it's only doing it on acceleration (or revving) that seems classic for a bad seal on the valve stem. If this is the case, you can fix it without tearing down the motor. Worth checking into. Tim Quote Link to comment Share on other sites More sharing options...
Nigel Posted June 17, 2002 Author Share Posted June 17, 2002 A stem seal would certainly be more manageable. I'm going to see my engine builder tomorrow to talk with him and see what his opinion is. I've got the wet plug with me for him to look at. Still hoping for the best... Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 17, 2002 Share Posted June 17, 2002 Well he would have to dog the engine to really get a haze, and that is a until it is broken in. I hope it is a valve stem seal. Man I hate those wavy rings, they suck. Quote Link to comment Share on other sites More sharing options...
Nigel Posted June 17, 2002 Author Share Posted June 17, 2002 I didn't have time to go to the shop today, so no input yet from the builder. I'd be awfully surprised if he screwed up the oil ring. He's been building these things for years. Not that mistakes don't happen from time to time... I wish I had one of those fiberoptic inspection gizmos. Then I could just look up at the valve and see if it's wet. Oh yeah, is there any way to tell if a bad turbo seal could be contributing to the smoke (no effect on the plug of course). I removed the down pipe to get the trany out, and the inside of the turbine is grey/black. There's noting obvious to suggest a seal problem there. I already had to send the turbo back because the seal had not been machined properly. I'm paranoid that it could still be leaking too. Thanks guys! Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 18, 2002 Share Posted June 18, 2002 Tim I think for the most part you are right, except when you over lap the oil control wavy ring, rather than just butt them together, which is what I did. Oil would get by it a little at a time, and POOF, I would get a puff of smoke. Not every time, and I did not let it happen much before the engine got snatched and re-rung. It is a very easy thing to do, and I know how meticulous I was during the ring installation. If his valve stem seal is leaking, he should see oil on the backside of the valve too, right? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted June 18, 2002 Share Posted June 18, 2002 If his valve stem seal is leaking, he should see oil on the backside of the valve too, right? Right, and he would generally not get the piston face mucky either.I see what you mean about the oil ring installation, but I am not wholly convinced that it would be noticed only during acceleration/revving. I would think that you would get a slight haze out of the tailpipe that is unrelated to rpm, but then I don't have the experience with the situation that you do, I am only using the very basic engine theory knowledge that I have. It would suck to have to tear down the motor again!!! At least it can be chalked up to practice!! Tim Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 18, 2002 Share Posted June 18, 2002 Who is building your turbos? I have seen 1 turbo seal problem, even though the guy would not own up to it. 300zxtt and the turbo on one side smoked something awful at idle, set it back and he checked it and said nothing was wrong with it, but it quit smoking after that. Hum.... I have an intermitant oil smoke problem that may be a seal too. I get smoke when I build a little boost and shift gears. I don't have any oil in the compressor housing, but have not gotten all the junk off to check the turbine. Mine could be rings, or valve stem seals, or turbo. This engine has had a hard life, so even if it were the engine, I would not be upset. Good luck. I hope it is something simple. Quote Link to comment Share on other sites More sharing options...
Nigel Posted June 19, 2002 Author Share Posted June 19, 2002 I don't know who did the turbo. It was sent out by the shop that did my engine. Who ever it was, they did own up to the fact that they hadn't machined it properly. I'm sure it's fine now, it's just that with so much going wrong, I get worried. I spoke with my engine builder yesterday, and showed him the wet plug and described the symptoms. He said not to panic yet and put some more miles on it, but to keep a close eye on it. So, at least now he's aware of the situation. Now I just have to put my transmission back together... Nigel Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 24, 2002 Share Posted June 24, 2002 Just make sure you keep a watch on your oil level for the while and see what is happening. Hope you are right and the engine is really ok, that would be great. Quote Link to comment Share on other sites More sharing options...
Nigel Posted June 25, 2002 Author Share Posted June 25, 2002 Good News! After I got the transmission back together and installed, I took the car for a nice strong run. I kept the revs below 4K and stayed out of the boost, but I gave the engine a good workout and put some load on it and... no more smoke or oily plug! I guess the rings just hadn't bedded in before. Happy again... Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
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