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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / February 2007TTY head bolts - replace?
I'd always thought that any head bolts should be replaced, but even more important for tty bolts. Local nissan tech says no - not necessary. Do I believe him? > I'd always thought that any head bolts should be replaced, but even more > important for tty bolts. > Local nissan tech says no - not necessary. > Do I believe him? Nope. If the specs in the factory shop manual are something like "xx ft-lbs + yy degrees" the bolts should be replaced. In fact the FSM will probably tell you specifically to replace them. If they are TTY, you might want to consider replacing them with ARP, which would be reusable. I'd prefer studs to bolts, makes positioning the gasket easier and they are theoretically more reliable. nate  Signaturereplace "roosters" with "cox" to reply. http://members.cox.net/njnagel >> Do I believe him? > > Nope. Why not? Depending on the application, he may be right. > If the specs in the factory shop manual are something like "xx ft-lbs > + yy degrees" the bolts should be replaced. In fact the FSM will > probably tell you specifically to replace them. Not true! Just because a bolt has a torque/turn value does not mean that it is a "torque to yield" bolt that needs to be replaced. Best to follow what the factory service manual says. I can't speak to other brands, but GM will always tell you whether a bolt has to be replaced or not. Trust me, not all torque/turn bolts have to be replaced. Ian > Not true! Just because a bolt has a torque/turn value does not > mean that it is a "torque to yield" bolt that needs to be replaced. [quoted text clipped - 4 lines] > > Ian I had heard the same story as Nate, but good to know that there are exceptions to every rule. One of our engineers also told me that if I install studs, as was mentioned earlier, that I would have to have the engine bored with studs in place and with a plate installed. I never heard this before, but would appreciate any comments. I think it is the best of best if you can do the boring with a plate torqued down and with the engine heated to operating temperature, but I didnt really think there would be a difference between bolts and studs. ?? Use a torque wrench and the same old headbolts,if you want to. cuhulin You are way out in the sticks,no access to new bolts.You think you will have any lesser luck with the same old bolts than new bolts? You will not. cuhulin > You are way out in the sticks,no access to new bolts.You think you will > have any lesser luck with the same old bolts than new bolts? You will > not. > cuhulin You certainly WILL... IF the old bolts were "torque to yield" or if they have been elongated/necked more than the manual allows. Not all head bolts are intended to be reused. Many years ago,about once or twice each month,people used to remove the cylinder heads from their vehicles.They would scrape out the carbon,put on a new head gasket,use the same old head bolts and torque wrench or no torque wrench,tigten her down and keep on driving.All the new bolts in the World will not do you any better than good usable old head bolts. cuhulin > Many years ago,about once or twice each month,people used to remove > the cylinder heads from their vehicles.They would scrape out the > carbon,put on a new head gasket,use the same old head bolts and > torque wrench or no torque wrench,tigten her down and keep on > driving.All the new bolts in the World will not do you any better > than good usable old head bolts. Ummmm.....the year is 2007. Ian > Many years ago,about once or twice each month,people used to remove the > cylinder heads from their vehicles.They would scrape out the carbon,put > on a new head gasket,use the same old head bolts and torque wrench or no > torque wrench,tigten her down and keep on driving.All the new bolts in > the World will not do you any better than good usable old head bolts. > cuhulin Unless, of course, the torque spec is such that the bolt is permanently deformed by the act of torquing it down. Which can and does happen. Back in the ancient days you describe, head bolts were simply good quality standard cap screws, and they were sized/torqued so that didn't happen. That is not always the case on a modern engine. nate Signaturereplace "roosters" with "cox" to reply. http://members.cox.net/njnagel Nate Nagel <njnagel@roosters.net> wrote in news:erllh741vk8 @news2.newsguy.com: >> Many years ago,about once or twice each month,people used to remove the >> cylinder heads from their vehicles.They would scrape out the carbon,put [quoted text clipped - 5 lines] > Unless, of course, the torque spec is such that the bolt is permanently > deformed by the act of torquing it down. Which can and does happen. I thought that was what "torque to yield" means. The bolt is tightened just to the point where it's permanently stretched, which is why that sort of bolt needs to be replaced if removed. SignatureTegger > > Unless, of course, the torque spec is such that the bolt is permanently > > deformed by the act of torquing it down. Which can and does happen. > > I thought that was what "torque to yield" means. In order for any word or phrase to have any meaning it needs to be used correctly. In this thread, the only thing that is known for sure is that the OP has failed to ask a meaningful question. The question is - should the OP get new head bolts? What kind of engine is unknown. Someone might guess it is some kind of Nissan because a Nissan tech is said to have offered an opinion. But who knows, the Nissan tech might just be his neighbor and the engine in question might be a lawn tractor. Presumably the tech has told him that he doesn't have TTY bolts and yet the idiot asks a question about TTY bolts and asks if he should believe the tech (without actually knowing what the guy told him). So my take is - even if the "tech" is retarded and has an IQ of 40 and just sweeps the floor down at the Nissan dealership I would say the the tech is probably right simply because he has to be a little smarter than the guy asking the question. -jim > The bolt is tightened just to the point where it's permanently stretched, > which is why that sort of bolt needs to be replaced if removed. > > -- > Tegger > Many years ago,about once or twice each month,people used to remove the > cylinder heads from their vehicles. You are so FOS its simply amazing. Not even a Model T needs that frequent head-removal. Sheesh. > I had heard the same story as Nate, but good to know that there are > exceptions to every rule. There are many folks who do not realize that there is a difference between a "torque to yield" bolt and one that simply has a "torque/turn" spec for tightening it down. On the other hand, it certainly would never hurt anything to replace head bolts when doing a repair job. > One of our engineers also told me that if I install studs, as was > mentioned earlier, that I would have to have the engine bored with > studs in place > and with a plate installed. I never heard this before, but would > appreciate any comments. Since I've never been into performance applications, I don't have a definitive answer for this. I've always thought that bolts or studs notwithstanding, a performance machine shop would always bore cylinders with torque plates installed. Ian >> Not true! Just because a bolt has a torque/turn value does not >> mean that it is a "torque to yield" bolt that needs to be replaced. [quoted text clipped - 17 lines] > really think there would be a difference between bolts and studs. > ?? Yes you should use a torque plate on a performance engine with studs. The reason is that the bore will distort some when the studs are torqued down. So you heat the block and torque the studs down and then do the final honing. You also want to install the main caps since they can cause the bottom of the bore to move a bit as well. This goes along with all the other machine work done in order so you don't mess up the block. BUT the above really only applies if your building for max performance. For a street engine you could install studs and call it close enough. TTY bolts are use once and replace. Torque+angle bolts MAY be able to be reused. If you can reach both ends of a bolt a stretch gauge is great, if your using a stud it is possible to use one but not easily. SignatureSteve W. Near Cooperstown, New York > > I had heard the same story as Nate, but good to know that there are > > exceptions to every rule. > Yes you should use a torque plate on a performance engine with studs. Agreed, a torque plate should be used for best results in any application. IMO, the engine should be at operating temperature when the boring is done ("hot boring"), as this further simulates the stresses on the engine under presumed operating conditions. My question was not the above, but rather if I must use studs on the torque plate if I intend to stud the engine, or if bolts would give the same distortion pattern during boring and still allow me to use studs during assembly. My opinion is that it will be close enough for a good street rebuild. I have a couple of old buddies who are Railroad nuts. Ordinary auto engines though,I have rebuiilt a few of them before and I always reused the same old bolts.I never had a problem with them later on either.But,if you want to buy new bolts,studs,whatever.Go for it. cuhulin > I have a couple of old buddies who are Railroad nuts. > > Ordinary auto engines though,I have rebuiilt a few of them before and I > always reused the same old bolts.I never had a problem with them later > on either.But,if you want to buy new bolts,studs,whatever.Go for it. > cuhulin The thing is; some engines are different than others. That is why specific information is essential. Torque plates are used for keeping the block cylinder area flat and straight,while you are doing other things.I did not cheat and look it up first on the internet.I am only recalling from memory (if you can call it that?) from an old magazine article I have somewhere around here. cuhulin > Torque plates are used for keeping the block cylinder area flat and > straight,while you are doing other things.I did not cheat and look it up > first on the internet.I am only recalling from memory (if you can call > it that?) from an old magazine article I have somewhere around here. > cuhulin Well, plates allow you to induce a similar level and pattern of stress into the block as you would expect with a head bolted in place. This lets you bore through the stress distortion, more or less. It is very common to set up the boring bar with no torque plates at all, and that is probably good enough for some rebuilds. When you circulate hot water through the block as you bore, it helps balance another possible source of stress distortion. That is how I understand it, at any rate. In my case, I had the block bored, all the parts balanced and matched, but had intended to put it together with studs. Was told I couldnt do it. But Im do not intend to take it back to the machine shop at this point and have them do it over again (unless powerful evidence surfaces that I MUST.;>) I wont be racing this little demon anyway. >> Torque plates are used for keeping the block cylinder area flat and >> straight,while you are doing other things.I did not cheat and look it up [quoted text clipped - 22 lines] > > I wont be racing this little demon anyway. No problem using studs that I can see. Be aware that studs can make it a PIA if you ever need to pull a head off from an engine that is installed in a vehicle. Just use a good set of studs (ARP has some of the best) And make sure you use sealer on them if required. SignatureSteve W. > Torque plates are used for keeping the block cylinder area flat and > straight,while you are doing other things. Not really, flatness has little to do with boring plate's function. Its real job is to put the correct TWISTING stresses on the bores, which are caused by the head bolts. Torquing the bolts pre-distorts the block, you bore a round hole, take the plate off and the hole goes un-round. Assemble the engine, and then torque the heads on and the cylinder goes BACK to being as close to perfectly round as possible. >>Not true! Just because a bolt has a torque/turn value does not >>mean that it is a "torque to yield" bolt that needs to be replaced. [quoted text clipped - 12 lines] > and with a plate installed. I never heard this before, but would appreciate > any comments. You should do that even with BOLTS! No reputable engine builder would do otherwise. > I think it is the best of best if you can do the boring with a plate torqued > down and with the engine heated to operating temperature, but I didnt > really think there would be a difference between bolts and studs. > ?? I would say that there's not. And in fact I'd say studs would be less likely to distort the bore than bolts. But a "torque plate" with all the fasteners torqued down to the same value as the cylinder head will have is the ONLY way to go, regardless. >> I'd always thought that any head bolts should be replaced, but even more >> important for tty bolts. [quoted text clipped - 12 lines] > >nate TTY intentionally stretches the fastener to the point just before yield. Torque plus turn is many times considered to be more accurate for fastener stress and gasket compression. It also tends to ignore the effect of thread friction where a lube (if any) is not as specified resulting in more accurate setting. The method I had a dard time wrapping my head around was the Kanichi (spell?) wrench I saw being used to troque the head bolt on the B5.9L Cummins at the factory a few years ago. It uses a sonic sensor to determine when correct torque has been reach based on sound pitch. It apparently works just fine in practice. Lugnut > TTY intentionally stretches the fastener to the point just > before yield. Torque plus turn is many times considered to [quoted text clipped - 9 lines] > > Lugnut I have seen adverts on bolt elongation gauges, but have never worked with one. They claim it is the 'only' way to fly. Have you guys ever worked with one of these. >> TTY intentionally stretches the fastener to the point just >> before yield. Torque plus turn is many times considered to [quoted text clipped - 14 lines] > >Have you guys ever worked with one of these. Some time in my past, we used stretch guages on many of the fasteners in the locomotive engines. The mains were a 3" diameter stud about 20" long. We "snugged it up" at 1200 ft lb and then put the guage on to stretch the suckers another 0.030". The rods started at 900 ft/lb and stretched 0.060". It could be a bear getting them tight if your air pressure dropped under 250 psi at the wrench. Lugnut > Some time in my past, we used stretch guages on many of the > fasteners in the locomotive engines. The mains were a 3" [quoted text clipped - 3 lines] > It could be a bear getting them tight if your air pressure > dropped under 250 psi at the wrench. EMD, Alco, or GE 7FDL prime mover?? Just curious. >> Some time in my past, we used stretch guages on many of the >> fasteners in the locomotive engines. The mains were a 3" [quoted text clipped - 5 lines] > >EMD, Alco, or GE 7FDL prime mover?? Just curious. Alco 2-51 & GM 8-238's. Had some Fairbanks 10 cyl OP's that had some stretch specs. Nothing like working on something big enough you can find it when you drop it! Our apps were marine - not actual loco except in yard duty equipment. Lugnut >>EMD, Alco, or GE 7FDL prime mover?? Just curious. > > Alco 2-51 & GM 8-238's. Had some Fairbanks 10 cyl OP's that > had some stretch specs. Nothing like working on something > big enough you can find it when you drop it! Our apps were > marine - not actual loco except in yard duty equipment. The Alco 251 is still in production for marine use. So is the Fairbanks-Morse OP- the us Navy uses a lot of them for auxiliary powerplant. Actually, F-M and Alco are both part of the same company now- interstingly called "FM-Alco" :-) >>>EMD, Alco, or GE 7FDL prime mover?? Just curious. >> [quoted text clipped - 7 lines] >powerplant. Actually, F-M and Alco are both part of the same company >now- interstingly called "FM-Alco" :-) My experience with them was USCG. Loved the ALCO's and F-M. They have both been thru several owners since I trained at the ALCO plant for several months in 1967. The feeling of brute power standing between a pair of V16 ALCO's at full power is incredible. You can feel the turbos sucking everything in from 6 feet away from the intake. It is almost unreal the wear and abuse the things can take and still do their job at full power as long as you keep oil and water in them. It was like old home week about 10 years ago when I got an opportunity to spend some time at the throttle of some Locos with CSX that had the Alco's. Most of the newer locos are running the EMD's. Automobile technology is incredible these days but, to me, no more awsome than those big bruisers even after I lived with them a few years. Lugnut I own a big old cast iron Leo number 3 Railroad Depot heater,it was made in Chattanooga.It is sitting on my front porch,it must be at least one hundred years old.A couple of my buddies are Railroad nuts,they own a bunch of old Railroad related things.Things such as lights,signs,switches,insulators,speeders,lots of other Railroad things. cuhulin I would agree with replacement, due to lack of further information on their age or if they have been loosened in the past. SignatureKnifeblade_03 http://www.automotiveforums.com
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