zeiss150 Posted January 3, 2011 Share Posted January 3, 2011 (edited) Hey Guys! I was wondering if anyone had tips on getting an a torque wrench on to the exhaust nuts. I can't seem to get a socket onto the nuts in a way that I can use a torque wrench. I think last time I used a wrench and just "guessed" when it was torqued enough (Lame, I know!) So any advice would be AWESOME! I wanna make sure I don't have any exhaust leaks when I put it all back together again. May the force be with you! Matt- Edited January 3, 2011 by BRAAP Advertised parts removed from post. Quote Link to comment Share on other sites More sharing options...
hoov100 Posted January 3, 2011 Share Posted January 3, 2011 Just get them really tight. They need to be tight enough to seal and tight enough not to come undone. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 3, 2011 Author Share Posted January 3, 2011 they Haynes manual says that the torque is 8#'s that's not very much. I suppose that is just "tight". I just don't want an exhaust leak. Does anyone know if the turbo manifold gasket is any better or does it matter? Matt- Quote Link to comment Share on other sites More sharing options...
ktm Posted January 3, 2011 Share Posted January 3, 2011 They only need to be tight enough to press the manifold against the gasket hence the 8 ft-lb torque requirement. If you try to tighten them too much, you'll strip the threads in the head. This is why using studs for the exhaust manifold is preferred over bolts. Tighter is not necessarily better. Quote Link to comment Share on other sites More sharing options...
rossman Posted January 3, 2011 Share Posted January 3, 2011 (edited) You might also want to consider using these all-metal self locking nuts. They are reduced diameter so you can use a smaller socket making access easier. Edited January 3, 2011 by rossman Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 3, 2011 Author Share Posted January 3, 2011 Yeah I'm using studs. I just wish I could get a torque wrench on them... oh well. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 3, 2011 Share Posted January 3, 2011 It is possible if you can find the right combination of extensions with the right socket on the end. I think I had two longs and a short (maybe two 6" and a 3"?, not sure of the lengths). It's almost a straight shot to all of them except the one in the front, which will be cocked a little bit, If I recall correctly. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 4, 2011 Share Posted January 4, 2011 I've heli-coiled one of my cylinder heads and will do the other when I need to pull the intake and exhaust. Using a header has lead to leaks when not tightening in some given sequence. My personal experience has been to snug up everything then do a final torque starting with the lower hardware first then move on to the nuts clamping the intake/exhaust together and lastly the upper intake hardware. I've never experienced a leak since following this procedure. It might not be an issue with the stock exhaust manifold. A torque wrench has never been used. Grandpa always said "Tight is tight". That applies to most everything in life... Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 5, 2011 Author Share Posted January 5, 2011 I torqued the manifold nuts to about 10lbs (the manual says 8lbs but whats an extra 2 lbs?) and I was able to get a torque wrench on almost all of them. I think there were 2 that I couldn't get a wrench to so I just used my built in torque wrench in my elbow. I'll have the head all buttoned up tomorrow and I'll crank it over and see if I have any exhaust leaks. Thanks for the help guys! Matt- Quote Link to comment Share on other sites More sharing options...
rossman Posted January 5, 2011 Share Posted January 5, 2011 (edited) The numbers are seemingly small but 2 ft-lbs is 25% more torque. To give you an idea of the force on the bolt, the rough calculation I use for bolt preload is Fp = T/(kD). Assuming D = .315 (M8?) and k = .15 for lubricated threads... Fp = 24/(.15*.315) = 500 lbs of additional preload from ONLY 2 ft-lbs of additional torque. So now you have an additional 500 lbs of force trying to pull out of those aluminum threads. Edited January 5, 2011 by rossman Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted January 5, 2011 Share Posted January 5, 2011 (edited) You all missed an important issue that was brought to my attention a couple years back: Tensile strength. Original Datsun/Nissan studs did not receive just a superseded part number. You will have to verify new studs and torque accordingly. There are 3 or 4 different studs out there. original studs, upgrade for those studs with supposedly better studs, and there are the turbo studs, and I believe they also had an upgraded stud come out for the turbo as well. Both the upgraded studs for the turbo and the non-turbo are orderable and possibly available through your local dealer. They were using high tensile strength originally which would get shocked and snap from heat cycling. They went to a slightly softer material capable of resisting the heat cycling. They also changed the protective coating over the years. But the important issue is that it becomes critical as to what you torque these to depending on which stud you end up with. Depending on which stud is in your hand will determine how well it handles the torque and heat cycling. Obviously then one would be more prone to failure than the other. Ive never had or seen a stud pull the threads out of a L series head. They almost always break flush or above. Ive over torqued a few of these and snapped them clean off. Yes I know, dumb right? Anyway threads were still fine. Those aluminum threads will take a beating. The studs are and were meant to be the weak point and they will break or strip before the cylinder head threads. Using the wrong studs could easily result in cylinder head thread damage(and we are not talking incorrect thread pitch). On my personal L6's I double gasket using the composite type gaskets(shiny silver ones). I use a Nissan stud, part number is in my build log somewhere, but its not a std L series stud and it works at 15lbs of torque. The stud I use is readily available and always in stock at the dealer. Its from a mid 90's Nissan is all I remember off hand. I started using this setup on my l28et with 18lbs of boost. If the heat cycling and back pressure didnt blow out the gasket or snap a stud there I figured its good enough for any of my non-turbo L series setups. I am not an expert on the subject. Im just relaying what I have learned. I spent a lot of time at dealership digging through Nissan studs an figuring out their applications and properties(which isnt easy). Then there was all the trial and error on my L28et and the ever warping manifolds. Perhaps someone with some real knowledge will chime in and confirm or deny my findings. All I know is it has worked for me for over 6 years and until it doesnt work anymore thats what Ill continue to do. I can torque all of them straight on but 1 on my SU's. With EFI there are like 2 studs that are hard to reach. Its the intake manifold that determines which ones you will be able to reach straight on. EFI has that heat shield to that has allowance for a socket, but it makes it even more difficult to get the socket on the nut. Late model ZX's seam to be the worst and it may be easier to remove the heat shield that hangs down vertically if you can get the 10mm headed bolts out. The ONLY time Ive seen thread damage in the head is when someone(including myself) attempts to remove a broken stud. The act of removing said broken stud causes the damage not the actually breaking of the stud. Drill bits, extractors, center punches, chisels, hammers, etc being the executioner of our threads not over torqued studs. Edited January 5, 2011 by rayaapp2 1 Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted January 5, 2011 Share Posted January 5, 2011 Another "tip" if you will - once the engine heat cycles a couple times, you'll want to go back and re-torque, as dissimilar metals will expand and contract under heat and can sometimes loosen themselves up. I always retorque after the engine cools after several trips up to operating temperature. There's usually a little "slop" in a few of the bolts. I also re-torque (just about everything on the car) before a track event. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 6, 2011 Author Share Posted January 6, 2011 Everything looks good. I don't seem to have any leaks yet. I'll go back and re torque the studs after a few more warm up cycles. By the Way I'm using an SU and header setup with a P90 head. So far it seems to be working GREAT! Thanks for the advice! Oh yeah when i took off the old gasket I could see that I had a massive exhaust leak right at the center of the header. You can see were the gasket wasn't sealing. Now wonder I always smelled like exhaust! Matt- Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted January 6, 2011 Share Posted January 6, 2011 That's good that you found an exhaust leak - but you may not be out of the woods just yet. A good bit of exhaust fumes can seep in under a bad hatch seal, bad taillight seal, or any other open orifice into the cabin. I have also found that using a 90 degree exhaust turndown at the end of the tailpipe does wonders to cure exhaust seepage. Point it at the ground. It may look retarded, but dang it works. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted January 6, 2011 Share Posted January 6, 2011 Hopefully you checked your exhaust manifold flange for straightness? A straight edge and a feeler gauge goes a long way. Odds are that if you had a leak, you also have a warp and it should be checked. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 10, 2011 Author Share Posted January 10, 2011 Hopefully you checked your exhaust manifold flange for straightness? A straight edge and a feeler gauge goes a long way. Odds are that if you had a leak, you also have a warp and it should be checked. I don't think it was a warp in the header. it was the very center of the exhaust flange only about 3 inches and then it sealed again. I think the bolts just weren't tight enough. It seems to be sealed just fine now. No exhaust leak so far. My car is pretty buttoned up. I have all the door and hatch seals nice and tight. I also have my tail pipe pointed at the ground. I'm just going to re-tighten the nuts one more time and make sure they didn't loosen and then I'm gonna leave it! Rock on party people! Matt- Quote Link to comment Share on other sites More sharing options...
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