Phillip Posted February 25, 2009 Share Posted February 25, 2009 Hey, I recently just put a new full exhaust system on from MSA, 3-2 headers and their 2.5" exhaust. After the install the engine compartment is still just as loud as when there was only a manifold(even though I have full exhaust now), and there is an extremely loud "knocking" noise coming from around cylinders 5 or 6 anyone know what could be causing this? If this has been posted before sry I could not find it. Thanks! Quote Link to comment Share on other sites More sharing options...
islanddozer Posted February 25, 2009 Share Posted February 25, 2009 Knocking noises are never good. You have new gaskets for that exhaust ? Torqued all bolts ? Any performace or idle problem ? Quote Link to comment Share on other sites More sharing options...
AK-Z Posted February 25, 2009 Share Posted February 25, 2009 do a compression test Quote Link to comment Share on other sites More sharing options...
capt_furious Posted February 25, 2009 Share Posted February 25, 2009 Have a close look at the new exhaust itself and try to determine if it's hitting anything. If it's really close to any sheet metal or suspension components, vibration at idle could be bouncing it off of something. When you say 'extremely loud', is it a metallic clank knock, like a pipe against a hard surface, or an internal 'clonk' from within the engine itself? Is it synced with the engine ignition? Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 25, 2009 Author Share Posted February 25, 2009 for one the engine itself is extremely loud atm can't hear exhaust over it, and the knock is in sync with the ignition and even louder than the engine, sounds like its from 1cylinder either #5 or #6, it doesn't sound like a pipe hitting anything because I don't think that would hit as often as the sound happens. There is a brand new gasket on it, although I did have some problems with the nuts that torque to like 12lbs, the flange on the header is really thick but on the intake manifold its thin, are the nuts supposed to be touching both? or just the header? I do have some idling problems, but thats because I just got car running and im gonna adjust ignition timing today, would that be a problem? does that help ? thanks for replying! Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 26, 2009 Author Share Posted February 26, 2009 Ok so I just unplugged cylinder #6's fuel injector, and the knocking sound stopped, but then of course rpm were messed up at higher rpm. I plugged the injector back in and the knocking sound came back, any thoughts? Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted February 26, 2009 Share Posted February 26, 2009 go on youtube and search "Nismopicks l28et rod knock" or something like that, does it sound like that? Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted February 26, 2009 Share Posted February 26, 2009 heres a link Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 26, 2009 Author Share Posted February 26, 2009 on youtube the video "944 turbo lifter noise or rod knock" is the exact sound i'm getting here's link Quote Link to comment Share on other sites More sharing options...
islanddozer Posted February 26, 2009 Share Posted February 26, 2009 do you have an injector to swap ? could be that injector. have you pulled the plugs ? compression test yet ? Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 26, 2009 Author Share Posted February 26, 2009 I didn't have anyone to do compression test with, If theres a good chance its the injector ill buy one rq and swap it, i pulled the plug from the 6th injector, and car sounded fine besides for the engine being way to loud imo, ill see if I can get a friend to help me with compression test. it seriously sounds like a rod knocking, but i don't get why it stops when injector plug is pulled, because piston is still going up and down right? Quote Link to comment Share on other sites More sharing options...
woldson Posted February 26, 2009 Share Posted February 26, 2009 Yes, but, freely. Not nearly the amount of force being applied to the rod/cap. As time passes and the problem get worse, if it is rod knock, you will hear it under all conditions. (even starting) By then your very done and need to be fliped. Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 27, 2009 Author Share Posted February 27, 2009 I can hear the knock while acceleterating, it starts up normal but then immediately goes to knocking, when cylinder #6 is unplugged I can still faintly hear it, so this would be a rod knock? If so then im gonna rebuild the engine :/ Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 27, 2009 Author Share Posted February 27, 2009 Ok, so I have decided I am going to swap to a 280zx turbo engine so I can drive the car, while im rebuilding the stock motor. Does anyone know if 3-2 Headers from MSA (round exhaust ports) fit over the square exhaust ports of a 280zx turbo engine? thanks much! Quote Link to comment Share on other sites More sharing options...
GOTAZ Posted February 27, 2009 Share Posted February 27, 2009 Phillip, Any chance something fell into the # 5/6 intake/exhaust ports during the header swap? Any stripped flange studs/nuts? Have you tried using a stethoscope to help pinpoint the location? As for my experience with MSA headers: They didn't clear the Bob Sharp 4bbl intake already in use. They hit each other; not allowing the gasket faces to sit flat against the head. It took many trial fittings and 3 new gaskets (destroyed two in process) after alternately filling the underside of the intake or violently (but carefully) customizing the interfering header pipe with a ball peen hammer. But, while having all this fun I was completely distracted from the need for a heat shield between the intake/carb & exhaust. Nutz. This really makes hot weather tuning a crap shoot. Which leads me to really really hate the yearly AZ rectal exams to get my tags renewed. Okay, no more venting, promise. Maybe Sincerely though, Good Luck. Doug. Quote Link to comment Share on other sites More sharing options...
Phillip Posted February 27, 2009 Author Share Posted February 27, 2009 well on the headers the nuts that are supposed to be touch both the intake manifold and the header, are a little messed up because, the header flange is twice as thick as the one on the exhaust manifold, thus the intake and header to not meet correctly, and the half circle where part of the nut is supposed to touch is too wide and my nut goes inside it, did you have to use washers? according to MSA you don't need washers if I read correctly, when I was installing the header I kept a garbage bag over the intake and exhaust ports so slim to no chance that something got into 5th or 6th cylinder Quote Link to comment Share on other sites More sharing options...
islanddozer Posted February 27, 2009 Share Posted February 27, 2009 I don't know about MSA headers but the nut is to hold the header to the head. If you have the nut inside the hole how is it supposed to hold tightly to the head. Try cutting washers in half and build up the intake and 1 full washer over all or just order the mounting hardware Quote Link to comment Share on other sites More sharing options...
dan5138 Posted February 27, 2009 Share Posted February 27, 2009 You said the engine sounded better with the plug on #6 injector removed. I would remove #5 and #6 injector plugs, and see what the engine sounds like. The only abnormal thing at this point is the engine should be missing noticably. How old are the injectors? Once the old ones start to go they can get pretty loud. When I first got my '76 it sounded like someone had the valves adjusted way slopy, and it ran rough. Replaced the injectors and it runs and sounds great now. Quote Link to comment Share on other sites More sharing options...
Phillip Posted March 1, 2009 Author Share Posted March 1, 2009 Well, now I can hear the sound pretty good, even with injector 5 and 6 unplugged, so its getting worse. I decided im going to rebuild the engine, was going to do it over the summer but now i have to lol. zstore/MSA quoted me 700-900bucks to buy everything to make a complete kit, does anyone know of a place that I could get cheaper? Quote Link to comment Share on other sites More sharing options...
islanddozer Posted March 1, 2009 Share Posted March 1, 2009 I used www.rockauto.com. Fast, cheap and stand behind their products. I use their site for part numbers and try to get what I can locally first. Quote Link to comment Share on other sites More sharing options...
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