stravi757 Posted September 11, 2011 Share Posted September 11, 2011 So heres the story. I picked up a 280zxt engine from the JY a while back that looked like it was rebuilt, the engine was super clean, all the gasket were new ect.. Before I went to install it i Did a compression test to find 0psi on every cylinder. I started taking everything apart and found that the timing chain had been installed incorrectly. I put it back on right. put a new headgasket, did a compression test and got 140psi across all cylinders. So now I put the engine in the car, wire it, and it fires first try and the engine is running real smooth, idle was perfect ect. But within a minute or so heavy smoke is coming from the exhaust. I let it keep running but the smoke just persists. the smoke is constantly coming out whether you rev it or let it idle. When you let it idle for a while then rev it, lots and lost of thick smoke will come out. I checked the PVC, no oil. I checked the J-pipe and throttle body, no oil. check the plugs and they all have oil deposits on them and numbers 1 2 and 5 are wet. I switched the turbo just for he hell of it, no difference. So I figure if the oil isnt coming through the intake it has to be coming from the valve guides/seals or rings. My question is can the oil be coming from the rings even with good compression? or could it be the valve seals? And how much smoke would there be if it was the valve seals, because the engine is making ALOT of smoke. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted September 12, 2011 Share Posted September 12, 2011 How much have you run the engine? If the engine is actually a fresh rebuild the rings are not seated, but this does not usually cause gross oil consumption. The rings could be stuck in the ring grooves which sometimes improves with use. Maybe you just need to run the eninge for a few hundred miles to get it loosened up and start seating the rings. Quote Link to comment Share on other sites More sharing options...
stravi757 Posted September 12, 2011 Author Share Posted September 12, 2011 How much have you run the engine? If the engine is actually a fresh rebuild the rings are not seated, but this does not usually cause gross oil consumption. The rings could be stuck in the ring grooves which sometimes improves with use. Maybe you just need to run the eninge for a few hundred miles to get it loosened up and start seating the rings. ive run the engine for about 25 minutes so far under no load. i guess I could drive the car a few hundred miles to perhaps properly seat the rings, but I would like to try and pinpoint my problem before doing something like that. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted September 12, 2011 Share Posted September 12, 2011 ive run the engine for about 25 minutes so far under no load. i guess I could drive the car a few hundred miles to perhaps properly seat the rings, but I would like to try and pinpoint my problem before doing something like that. Was the engine you removed pumping a lot of oil? Perhaps the exhaust is full of oil and it needs time to burn out. You said the smoke starts a minute or so after starting the engine suggesting the smoke comes after things get hot. If the rings are the issue it would smoke at start-up. The other possibility, if time is required before the smoke starts, is oil build-up in the top-end. Perhaps there is too much oil getting to the top or there are blocked oil return passages allowing too much oil to pool around the guides. Don't get to rushed looking for a problem that might not exist. It does not sound like any damage will be caused by running the engine more. Run the engine more and go for a drive if you can. Sometimes things need a little time to settle down. Check the oil a lot. If the oil level is not dropping quickly there is hope. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 12, 2011 Share Posted September 12, 2011 did a compression test and got 140psi across all cylinders That's a very low number. Most likely rings. When you had the head off did you check to see if the rings had stuck or rusted to the cylinder walls due to the engine sitting for a long time? Quote Link to comment Share on other sites More sharing options...
stravi757 Posted September 12, 2011 Author Share Posted September 12, 2011 Was the engine you removed pumping a lot of oil? Perhaps the exhaust is full of oil and it needs time to burn out. You said the smoke starts a minute or so after starting the engine suggesting the smoke comes after things get hot. If the rings are the issue it would smoke at start-up. The other possibility, if time is required before the smoke starts, is oil build-up in the top-end. Perhaps there is too much oil getting to the top or there are blocked oil return passages allowing too much oil to pool around the guides. Don't get to rushed looking for a problem that might not exist. It does not sound like any damage will be caused by running the engine more. Run the engine more and go for a drive if you can. Sometimes things need a little time to settle down. Check the oil a lot. If the oil level is not dropping quickly there is hope. There is just a down pipe after the turbo, nad it didnt smoke the first time i started it up, now it smoke immediately when I start it. Maybe it was possible I used the wrong head gasket and its blocking some oil passages? That's a very low number. Most likely rings. When you had the head off did you check to see if the rings had stuck or rusted to the cylinder walls due to the engine sitting for a long time? The cylinder wall had no rust at all on them when I took the head off. And I thought 140 psi was very close to the sock CR for a turbo engine? Quote Link to comment Share on other sites More sharing options...
johnc Posted September 12, 2011 Share Posted September 12, 2011 Oops. My mistake on the turbo engine CR. Quote Link to comment Share on other sites More sharing options...
stav2201 Posted September 30, 2011 Share Posted September 30, 2011 Im brothers with the OP, it seems as though the valve seals are worn. Perhaps from lack of lubrication from sitting so long and eventually drying? I am replacing them but im concerned with the valve guides while i have the head disassembled, any ideas on how much play there should be with the valves if any at all? Quote Link to comment Share on other sites More sharing options...
zack_280 Posted September 30, 2011 Share Posted September 30, 2011 Suggest some reading material. http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=how+to+rebuild+your+nissan&x=0&y=0 Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted October 1, 2011 Share Posted October 1, 2011 How many quarts of oil are in the sump? Is the dipstick the correct one for your car? Is this car equipped with an automatic transmission that could be sipping trans. fluid through the vacumm for the modulator? Just a few things to check before tearing down the engine. Also....how is the turbo drain path from turbo to pan? Quote Link to comment Share on other sites More sharing options...
stav2201 Posted October 1, 2011 Share Posted October 1, 2011 How many quarts of oil are in the sump? Is the dipstick the correct one for your car? Is this car equipped with an automatic transmission that could be sipping trans. fluid through the vacumm for the modulator? Just a few things to check before tearing down the engine. Also....how is the turbo drain path from turbo to pan? Correct ammount of oil Correct dipstick Manual transmission Im pretty sure its the valve seals, i just replaced them all today so hopefully i can finish adjusting the valves and have it running tomorrow. If it still smokes i guess my oil rings on the pistons are busted or my valve guides are worn (but they seemed fine when i was changing the valve seals). Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted October 1, 2011 Share Posted October 1, 2011 What happens when you remove the oil filler cap with it running? Quote Link to comment Share on other sites More sharing options...
stav2201 Posted October 1, 2011 Share Posted October 1, 2011 Finished adjusting the valves and got it running. Still burning the same amount of oil as before, my guess is the idiot who built the engine before i got it out of the junkyard put the oil rings on incorrectly. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted October 6, 2011 Share Posted October 6, 2011 You would be able to tell if it was rings or valve stem seals by listening to the oil cap when the engine is running. Quote Link to comment Share on other sites More sharing options...
stav2201 Posted October 7, 2011 Share Posted October 7, 2011 You would be able to tell if it was rings or valve stem seals by listening to the oil cap when the engine is running. what noise would it make if that was the case? Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted October 7, 2011 Share Posted October 7, 2011 (edited) On a L28 without excessive blow-by, you shouldn't hear anything. If you have blow-by you should hear a growling noise and putting your hand plugging the hole might even cause pressure to build that you will notice when you remove your hand on a car with huge amounts of blow-by. There are varying degrees of this and what I described is "whole engine blow-by" and just a single cylinder with the amount of smoking mentioned would manifest itself as muted pops through the oil cap hole instead of a groan. Usually, if an engine has enough blow by to make clouds of smoke, then you should expect that it will expel exhaust gases past the rings into the crankcase. A properly running L28 with stock breather hose routing may actually misfire as removing the oil cap will allow air that was not metered by the air flow meter to enter the engine and cause a miss in some cases. Some guys run into the misfire when they remove the hose that goes from the valve cover to the induction system between the air flow meter and the throttle body and instead use a filter on the valve cover barb. If you don't have any of the "blow-by" symptoms described, then rejoice that you instead have leaking valve stem seals. Of course, removing the head to fix the seals will also allow you to inspect the bores which might show some scuffing. Edited October 7, 2011 by HowlerMonkey Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 7, 2011 Share Posted October 7, 2011 I've told this story before, but one of my Z buddies had a friend who built a motor and then fired it up and just let it idle for something ridiculous like two hours. Thing was smoking like crazy. He calls my friend complaining that something is really wrong, etc. My buddy goes over and has a look and asks what he's done and is told about the long period of idling. So goes out for a drive and just beats the piss out of it. Up to redline and then back down, back up to redline, back down over and over. Comes back about 15 minutes later, pulls up, no smoke. I think before you pull the pistons and look at the oil rings, you might as well go drive the thing and do the same revving up and down bit. It's not going to hurt the motor in the long run, but it might save you some hours pulling the engine and the crank, etc. Quote Link to comment Share on other sites More sharing options...
stav2201 Posted October 8, 2011 Share Posted October 8, 2011 I've told this story before, but one of my Z buddies had a friend who built a motor and then fired it up and just let it idle for something ridiculous like two hours. Thing was smoking like crazy. He calls my friend complaining that something is really wrong, etc. My buddy goes over and has a look and asks what he's done and is told about the long period of idling. So goes out for a drive and just beats the piss out of it. Up to redline and then back down, back up to redline, back down over and over. Comes back about 15 minutes later, pulls up, no smoke. I think before you pull the pistons and look at the oil rings, you might as well go drive the thing and do the same revving up and down bit. It's not going to hurt the motor in the long run, but it might save you some hours pulling the engine and the crank, etc. I thought about doing that but i would of gotten pulled over by the police in my town and got a ticket if i did that. PLus, when i got the engine the guy put the timing chain on incorrectly. I figured if your gonna spend all this money rebuilding engine and put the timing chain on incorrectly whats going to stop this guy from putting oil rings or bearings on incorrectly. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 9, 2011 Share Posted October 9, 2011 Then I guess you're screwed, and are in for a teardown. Personally I'd run the hell out of it anyway and see what happens. You can get out of town to do this, you know. I've seen the same thing JM comments upon, as well as engines that have laid up in storage that got the rings stuck. Nothing wrong with them, just stuck from sitting. BTW, it's eTc, and pCv... Quote Link to comment Share on other sites More sharing options...
stav2201 Posted October 9, 2011 Share Posted October 9, 2011 (edited) well i decided to put everything back together and see what happens when i beat the crap out of the engine. I drove it around for 20 minutes cruising at about 4k rpms, still burning oil and smoking; i don't think it got any better. Ill try putting some thicker oil in it tomorrow and maybe it will make a difference. Is there a specific process i should follow while trying to beat the crap out of my engine? Edited October 9, 2011 by stav2201 Quote Link to comment Share on other sites More sharing options...
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