Iowa280zx Posted April 3, 2010 Share Posted April 3, 2010 Hey guys, I need a few pointers here... I have a 81 280zxt, it runs great, idles fine (most of the time) and is bone stock except for full 3 inch to 2.75 exhaust. The thing thats puzzling my atm is when I start the car up, it sounds like a normal Z does.. I hear an ever so slight chatter from the valves but it's not obvious unless you are really listening. But when I actually take the car out for a drive it's a constant ticking fest and it comes and goes when ever I give it gas and let off. It's quite noticable and extremely annoying. I never noticed it before I got my exhaust finished, but it's worlds quieter than it was and I'm assuming it was there but I just didn't hear it. Also, I've checked for exhaust leaks and didn't find any. Any ideas here or is it just my valves going bad? The only thing that confounds me is that the car drives fine other than the annoying sound. Quote Link to comment Share on other sites More sharing options...
l28t260z Posted April 3, 2010 Share Posted April 3, 2010 Hey guys, I need a few pointers here... I have a 81 280zxt, it runs great, idles fine (most of the time) and is bone stock except for full 3 inch to 2.75 exhaust. The thing thats puzzling my atm is when I start the car up, it sounds like a normal Z does.. I hear an ever so slight chatter from the valves but it's not obvious unless you are really listening. But when I actually take the car out for a drive it's a constant ticking fest and it comes and goes when ever I give it gas and let off. It's quite noticable and extremely annoying. I never noticed it before I got my exhaust finished, but it's worlds quieter than it was and I'm assuming it was there but I just didn't hear it. Also, I've checked for exhaust leaks and didn't find any. Any ideas here or is it just my valves going bad? The only thing that confounds me is that the car drives fine other than the annoying sound. have you checkd if its coming from the turbo? had that problem with my car when i first got me l28 in my s30... turbo wasnt getting any oil then burned up Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 3, 2010 Author Share Posted April 3, 2010 The turbo seems to be working fine and spools like a champ. Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 3, 2010 Author Share Posted April 3, 2010 I also just used some seafoam in the oil earlier today before I changed it. Didn't seem to make any difference. Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted April 3, 2010 Share Posted April 3, 2010 Hey Iowa, if I was guessing, without hearing the car run, I would say you probably need to do a "cold", then a "hot" valve lash adjustment. This is covered in Chilton, Haynes, & Nissan manuals; & is easily done the first time in a few hours. All you need is a feeler guage w/ SAE & /or Metric values (based on preference), a new valve cover gasket, & a couple of box end wrenches (17 & 19 I think, don't quote me though). Almost every Z I've ever owned has done this. This is a good place to start, but there are 4 or 5 other possible causes. But worst case scenario, you have a properly adjusted valve train for $15, then you can move on to more "serious" diagnosis. Also, if the exhaust was really loud, & now it's quieter, it could just be the "click" of the injectors, but I doubt it. Good luck man & post your findings. You need to get this fixed before you install that intercooler this week...LOL! Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 3, 2010 Author Share Posted April 3, 2010 (edited) Hey Iowa, if I was guessing, without hearing the car run, I would say you probably need to do a "cold", then a "hot" valve lash adjustment. This is covered in Chilton, Haynes, & Nissan manuals; & is easily done the first time in a few hours. All you need is a feeler guage w/ SAE & /or Metric values (based on preference), a new valve cover gasket, & a couple of box end wrenches (17 & 19 I think, don't quote me though). Almost every Z I've ever owned has done this. This is a good place to start, but there are 4 or 5 other possible causes. But worst case scenario, you have a properly adjusted valve train for $15, then you can move on to more "serious" diagnosis. Also, if the exhaust was really loud, & now it's quieter, it could just be the "click" of the injectors, but I doubt it. Good luck man & post your findings. You need to get this fixed before you install that intercooler this week...LOL! I did a cold adjustment earlier today and only got to drive the car for 5 minutes before the wife called and wanted me home. The noise never really changed from what I could tell. I'll do the hot tomorrow assuming it's not raining over here like crazy. Something tells me it's not going to fix it though. If I can get a quality sound clip from my digital recorder I'll post it up, 90% of the time it just gets wind noise and exhaust when I try lol. I remember having to clean the crap out on my old turbo eclipses lifters back in the day. Is that possible on a 81zxt or is it just one of those situations where once they get old you are just kind of s.o.l.? It's got to be somewhere in valve area from what I can tell. It's hard to diagnose it though since it won't make the noise unless i'm driving it Edited April 3, 2010 by Iowa280zx Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 3, 2010 Author Share Posted April 3, 2010 I did a cold adjustment earlier today and only got to drive the car for 5 minutes before the wife called and wanted me home. The noise never really changed from what I could tell. I'll do the hot tomorrow assuming it's not raining over here like crazy. Something tells me it's not going to fix it though. If I can get a quality sound clip from my digital recorder I'll post it up, 90% of the time it just gets wind noise and exhaust when I try lol. I remember having to clean the crap out on my old turbo eclipses lifters back in the day. Is that possible on a 81zxt or is it just one of those situations where once they get old you are just kind of s.o.l.? It's got to be somewhere in valve area from what I can tell. It's hard to diagnose it though since it won't make the noise unless i'm driving it one other idea I had was that maybe it's possible that the guys who did the exhaust missed a weld or something. I hear the normal injector chatter and the only time the clicking happens is under load and while driving. Sitting out of gear and revving the engine won't make it happen. Could a small exhaust leak like that cause the clicking nose? It's all in tune with the rpm of my car when I get going too and goes away when I am off the gas and cruising. Any other ideas would be much appreciated because it's driving me batty. Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted April 4, 2010 Share Posted April 4, 2010 Is the motor down on power? If it is could be exhaust leak, carboned up combustion chambers & the ECU is dialing the timing back under load, etc. Is it sluggish? Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 4, 2010 Author Share Posted April 4, 2010 Is the motor down on power? If it is could be exhaust leak, carboned up combustion chambers & the ECU is dialing the timing back under load, etc. Is it sluggish? Everything feels pretty strong. I'm only running 4-5lbs of boost though atm. I'm kind of leaning towards exhaust at the moment though. I'll throw it up on the lift tomorrow, check and post up what I find. Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted April 4, 2010 Share Posted April 4, 2010 OK, keep us posted..... Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 6, 2010 Author Share Posted April 6, 2010 Well I ended up putting the car up on a lift and noticed the guy who did my exhaust missed a few welds, so i patched them up. The noise is still there and I am totally unable to figure out where it's origin is. Any idea on worst case scenerios? Also.. I have the original n/a engine sitting around from the swap. Could it be worn rocker arms and could those be transferred from the n/a to turbo engine? It's a 83 and the turbo is a 81. Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted April 7, 2010 Share Posted April 7, 2010 Well I ended up putting the car up on a lift and noticed the guy who did my exhaust missed a few welds, so i patched them up. The noise is still there and I am totally unable to figure out where it's origin is. Any idea on worst case scenerios? Also.. I have the original n/a engine sitting around from the swap. Could it be worn rocker arms and could those be transferred from the n/a to turbo engine? It's a 83 and the turbo is a 81. Do the "hot" lash adjustment yet? Yep, rockers will transfer unless it's the 83 hydra-lifter head (P90A), but the cam they are broken into has to make the migration as well. Unfortunately, n/a cam specs are a little different than turbo for anti-reversion purposes, BUT will usually work well in most cases (see my sig specs). Worst case scenario may not be the reality, but if it makes the sound after getting into it & then letting off, it's probably a bad rod bearing. Bad main(s) bearings USUALLY knock all the time & get worse with load. A cracked ring land chunk(s) that moves " in & out" against the bore, but is held in place by the rings, will create extra clearance & therefore noise under load or warm up (but is usually accompanied by blue exhaust smoke, fouled plug, loss of power, etc). Try to systematically pull one plug wire at a time and listen for changes, or a clear up of the noise, to narrow it to the problemed cylinder(s), then inspect further. Quote Link to comment Share on other sites More sharing options...
kelltainer Posted April 9, 2010 Share Posted April 9, 2010 hey my car just started doing this today, lol. Mine was the speedometer gauge, the little clicker or one the bearing on it is messed up....im taking it to my buddies shop tomorrow to have him look at it but i can see it moving wierd and hear the clicking coming from it. May want to check it out on yours! Ill let you know what we do to fix it. Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 16, 2010 Author Share Posted April 16, 2010 Think I figured it out... I ended up going ghetto style and used gas line to poke around my engine and listen. There was a leak on the far rear of my exhaust manifold and I'm willing to bet there is a few more around there. This should be a big pile of fun since I'm not taking the head off, just the intake/exhaust. Quote Link to comment Share on other sites More sharing options...
woldson Posted April 17, 2010 Share Posted April 17, 2010 Common problem. You stated that your turbo spools like a champ, after that I kinda ruled out exhaust leak. Glad you found it. Quote Link to comment Share on other sites More sharing options...
Iowa280zx Posted April 17, 2010 Author Share Posted April 17, 2010 I got the intake/exhaust off in about 30 minutes and could see 3 nasty spots where it was leaking. Also... I found the last bolt on the exhaust manifold was broken off inside the block. God bless the junkyard that actually used that rear loop to pull the engine Something tells me this is going to really suck and I'm definitely not using a easy out on it. Quote Link to comment Share on other sites More sharing options...
borini63 Posted May 8, 2010 Share Posted May 8, 2010 (edited) It's time to upgrade the exhaust manifold bolts in your ZXT....it's a headache...I just let somebody else do it for me cost $900.Bigger bolts and that will last for ever. Edited May 8, 2010 by borini63 Quote Link to comment Share on other sites More sharing options...
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