1994SEV6 Posted October 27, 2011 Share Posted October 27, 2011 Hey there guys! I'm new to NPORA, but so far I like it a lot. The common problems and fixes section was amazing. I've been hearing about the exhaust stud manifold problem for some time now, and I'm fairly convince that I have this problem. Some people were trying to tell me I had a bottom rod knock, but I've been driving it for 6000 miles. Then some other people were certain it was a bent valve or lifter tap. I have no idea how ONE vavle would get bent, but the lifter seems to be very common. Anyway, this exhaust manifold stud breakage issue seems to be very widespread. I was just wondering if there was a way to confirm it for sure? I hear one idea of using the seaform in the intake vacuum and then see if the white smoke comes out near the engine. Seems fairly do-able but not entirely positive. Here's some info: my nissan is a 1994 SEV6 with about 130k miles. I bought it about 7000 miles ago and as far as I can tell, everything but the auto trans is original. About a week after I got it, the tapping occured. It's been worrying/irritating me ever since. I have seen some posts about how to fix the problem, but I don't want to go fixing something that ain't broke. I need to know how I can 100% positively confirm that it is the broken exhaust manifold studs causing the problem. Also, if not, what else could this be? Thanks in advance guys Link to comment Share on other sites More sharing options...
devonianwalk Posted October 27, 2011 Share Posted October 27, 2011 I personally havnt had that problem but, I'd suggest that you apply some pressure to the exhaust manifold while the engine is still cool to check if the knocking temporarily goes away. Link to comment Share on other sites More sharing options...
Precise1 Posted October 27, 2011 Share Posted October 27, 2011 /\Says the guy with the 10mm exhaust studs... Welcome!! Ok, I recommend removing the heat shields and looking to see if the studs/nuts are still there. Then, put a socket on them and try to turn them (checking to see if they are broken but haven't fallen out). Third, I HIGHLY recommend a mechanic's stethoscope for chasing noises ($5-10). You can use a tube (metal or even cardboard) or a solid rod (long screwdriver) as a makeshift noise transmitter/amplifier but the stethoscope is the way to go. B Oh, just leave the heat shields off, they are pretty much useless... Link to comment Share on other sites More sharing options...
Tungsten Posted October 27, 2011 Share Posted October 27, 2011 Oh, just leave the heat shields off, they are pretty much useless... A symptom of a broken exhaust manifold stud is a loud tapping noise that gets even louder under load. It almost sounds like a misfire or detonation if you are close to it. It may also most likely become quieter as the engine warms up and the manifold expands and seals from the heat. You can also see carbon deposits from the exhaust around the area in which it is leaking. Just do a YouTube search for broken exhaust stud sounds to hear what it is. There was at least one other member that posted an exhaust stud leak video and you could clearly hear the leak. 1 Link to comment Share on other sites More sharing options...
1994SEV6 Posted October 28, 2011 Author Share Posted October 28, 2011 A symptom of a broken exhaust manifold stud is a loud tapping noise that gets even louder under load. It almost sounds like a misfire or detonation if you are close to it. It may also most likely become quieter as the engine warms up and the manifold expands and seals from the heat. You can also see carbon deposits from the exhaust around the area in which it is leaking. Just do a YouTube search for broken exhaust stud sounds to hear what it is. There was at least one other member that posted an exhaust stud leak video and you could clearly hear the leak. Oh believe me, I searched extensively in this forum for results on exhaust stud manifolds. Nothing useful. I did rub my hands around the exhaust manifold to try to find some carbon deposits. My hands came back clean. I know what it sounds like, but that also sounds like a lot of other things. The tapping could be exhaust manifold studs, or a valve tap, or a lifter tap, or a rod knock. I just want to know how to know between the 4 Link to comment Share on other sites More sharing options...
ahardb0dy Posted October 29, 2011 Share Posted October 29, 2011 WELCOME TO NPORA, PICS !! Does the tapping noise go away after the engine warms up? Usually with a broken stud (studs), you will get the noise when cold and it will go away when warm, not all the time but mostly. The other common noise at start up is the lifter noise again when cold until the oil has a chance to make it to them than the noise goes away. Do you hear the noise all the time? Link to comment Share on other sites More sharing options...
1994SEV6 Posted October 30, 2011 Author Share Posted October 30, 2011 WELCOME TO NPORA, PICS !! Does the tapping noise go away after the engine warms up? Usually with a broken stud (studs), you will get the noise when cold and it will go away when warm, not all the time but mostly. The other common noise at start up is the lifter noise again when cold until the oil has a chance to make it to them than the noise goes away. Do you hear the noise all the time? I do hear the noise all the time. It is much louder when cold though. If it's plenty warm, I can still hear it if I listen for it when stopped. I can hear it tapping up until about 2.5-3k RPM when it goes too fast and just becomes one noise instead of individual taps. My muffler rusted out and fell off about two weeks ago. It broke at the flange connecting the intermediate pipe and the muffler. When I didn't have a muffler on, the tapping got MUCH louder. This last bit of info seems to convince me that it's an exhaust stud thing. If it was a lifter, then it wouldn't get louder from the muffler being off, right? Link to comment Share on other sites More sharing options...
Dowser Posted October 30, 2011 Share Posted October 30, 2011 Well if the exhaust is off and it hasn't been repaired yet, you should just look into Thorley Headers, or Pace setter's if no thorelys are available, replace the manifold with those, and however many broken studs you find, (I've never known a Pathfinder without a broken stud) replace with the much stronger grade nissan studs for the 300Z or go with bolts as some other have done. You'll be doing the Muffler and piping anyway so a little more can't hurt, and you'll get a bit more power out of the deal. Link to comment Share on other sites More sharing options...
1994SEV6 Posted October 30, 2011 Author Share Posted October 30, 2011 (edited) Well if the exhaust is off and it hasn't been repaired yet, you should just look into Thorley Headers, or Pace setter's if no thorelys are available, replace the manifold with those, and however many broken studs you find, (I've never known a Pathfinder without a broken stud) replace with the much stronger grade nissan studs for the 300Z or go with bolts as some other have done. You'll be doing the Muffler and piping anyway so a little more can't hurt, and you'll get a bit more power out of the deal. WOW!! the broken stud issue is really that widespread? That's ridiculous. That's what I have for sure then. The previous owner said it had an exhaust leak and then the tapping started about 3 days after I got it. How long does it take to just fix the studs, and how long does it take to replace the headers? Also, how much do said stronger studs cost? Can I only get them at the Nissan dealer? edit: LOL. nvm. Thorley headers can hit a grand easy. no thanks Edited October 30, 2011 by 1994SEV6 Link to comment Share on other sites More sharing options...
Dowser Posted October 30, 2011 Share Posted October 30, 2011 (edited) Thorely's aren't that expensive. Although they are more expensive then Pace Setters, You'll find not as many favorable reviews from the Pace setters brand. Stevo from Rugged Rocks is a member here that provides many products for our rigs and according to this link, the price is $469.95 and being a member here gets you a 5% Discount. That's a savings of $23.50 bringing the total to $446.45 before applicable taxes. Keep in mind that depending on how bad an exhaust leak is your manifold may be warped and need to be machined. Which may be an expensive requirement to keep your old manifolds. The Studs from nissan are quite expensive for what they are really. Everyone here will agree with that. I suggest speaking with our Nissan Parts Pimp, Alkorahil, in the Services area to get a quote. He can provide you with the best prices for Nissan replacement pieces hands down. If that is still too rich for your blood you can also get bolts like some other on here have down. I believe they have needed to tighten them after the fact at some point if I remember correctly. Once again, Pace Setters are considerably cheaper then Thorelys which may be another route. Edited October 30, 2011 by Dowser Link to comment Share on other sites More sharing options...
1994SEV6 Posted October 30, 2011 Author Share Posted October 30, 2011 Thorely's aren't that expensive. Although they are more expensive then Pace Setters, You'll find not as many favorable reviews from the Pace setters brand. Stevo from Rugged Rocks is a member here that provides many products for our rigs and according to this link, the price is $469.95 and being a member here gets you a 5% Discount. That's a savings of $23.50 bringing the total to $446.45 before applicable taxes. Keep in mind that depending on how bad an exhaust leak is your heads may be warped and need to be machined. Which may be an expensive requirement to keep your old manifolds. The Studs from nissan are quite expensive for what they are really. Everyone here will agree with that. I suggest speaking with our Nissan Parts Pimp, Alkorahil, in the Services area to get a quote. He can provide you with the best prices for Nissan replacement pieces hands down. If that is still too rich for your blood you can also get bolts like some other on here have down. I believe they have needed to tighten them after the fact at some point if I remember correctly. Once again, Pace Setters are considerably cheaper then Thorelys which may be another route. oh man. my heads? from an exhaust leak? The same heads that warp when you blow a head gasket? I thought those were for intake, not exhaust. How long would it take them to get to the "warped heads" phase? Link to comment Share on other sites More sharing options...
adamzan Posted October 30, 2011 Share Posted October 30, 2011 I think he means manifolds, not the heads . When I had my studs done by a shop (only 2 were broken but changed all anyways), they used ones from carquest I believe. Three years later and they are still working fine. Not everyone has had problems with pace setter headers but a lot have. If you decide to go that route check the welds when you get them. I got a set and they were fine . Link to comment Share on other sites More sharing options...
1994SEV6 Posted October 30, 2011 Author Share Posted October 30, 2011 I think he means manifolds, not the heads . When I had my studs done by a shop (only 2 were broken but changed all anyways), they used ones from carquest I believe. Three years later and they are still working fine. Not everyone has had problems with pace setter headers but a lot have. If you decide to go that route check the welds when you get them. I got a set and they were fine . oh!! ok. whew...i thought if my heads were warped just get out now. So, I've tried to apply pressure to the manifolds while it was cold. They don't really seem to budge. I also put my hand down there and felt some air, but it was cold air, so I think I was jut feeling air from the radiator fan. I didn't feel any warm air. Where do they leak from? the top, or the bottom, or some unreachable place or what? Link to comment Share on other sites More sharing options...
Dowser Posted October 30, 2011 Share Posted October 30, 2011 Thanks for the save Adamzan. Ya I meant to type manifold but I'm a zombie right now. Been sick for a week with no end in sight, and my kids keep me utterly exhausted. At any rate, I meant the manifolds tend to warp if left for long periods of time with broken studs. Once you determine whether or not you have a manifold leak, you could always just play it by year. Get whatever broken studs out that are broken, if any are broken at all, then take the manifolds and run a straight edge on them to see if they are still true. If they are warped, get a price quote to machine, go to a wreckers and see if you have luck there, etc, and weight those options against getting the headers. If the price is within a couple hundred bucks I'd opt for the headers myself. If the manifold is still, fine, then reuse it and call it good. I just figured if you were doing exhaust anyway it could be a good time for an upgrade. Link to comment Share on other sites More sharing options...
teixeira Posted November 1, 2011 Share Posted November 1, 2011 Pics? Link to comment Share on other sites More sharing options...
JamesRich Posted November 2, 2011 Share Posted November 2, 2011 It is a good time for an upgrade, because steeevo is waiting on a few more people to sign up for the thorley header group buy. James Link to comment Share on other sites More sharing options...
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