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Re: Mystery Nut--Anyone Identify?
"Elle" <honda.lioness@nospam.earthlink.net> wrote in
news:hIkbg.4307$y4.4095@newsread2.news.pas.earthli nk.net: > I took the exhaust manifold shroud off today. It is indeed > an exhaust manifold nut (with broken-off stud stuck in it). > It's the one nearest the distributor. > > I am amazed at how many people (Nasty, Tegger, Eric, > SoCalMike) nailed this, and with a fuzzy photo, too. What a > phenomenal newsgroup! Broken studs are very common. I had one too. Mine broke below the surface of the head. My mechanic removed it, but wouldn't tell me how (trade secret, or so he says...). It was done at the same time as my head gasket replacement, so the machine shop that trued the head probably did it. The problem is that exhaust pulses are quite violent. This is the reason you need heat-resistant "prevailing torque" nuts. The nuts don't vibrate off, but the pulses often break a stud. Funny, the one that broke on mine was the one nearest the timing belt. It must be a random thing. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: Mystery Nut--Anyone Identify?
"TeGGeR®" <tegger@tegger.c0m> wrote in
news:Xns97C8D2ABBFBEtegger@207.14.116.130: > > The problem is that exhaust pulses are quite violent. This is the > reason you need heat-resistant "prevailing torque" nuts. The nuts > don't vibrate off, but the pulses often break a stud. That combined with the exhaust system flexing as the engine torques on its mounts, of course... -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: Mystery Nut--Anyone Identify?
"TeGGeR®" <tegger@tegger.c0m> wrote in
news:Xns97C8D2ABBFBEtegger@207.14.116.130: > > The problem is that exhaust pulses are quite violent. This is the > reason you need heat-resistant "prevailing torque" nuts. The nuts > don't vibrate off, but the pulses often break a stud. That combined with the exhaust system flexing as the engine torques on its mounts, of course... -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: Mystery Nut--Anyone Identify?
"TeGGeR®" <tegger@tegger.c0m> wrote in
news:Xns97C8D2ABBFBEtegger@207.14.116.130: > > The problem is that exhaust pulses are quite violent. This is the > reason you need heat-resistant "prevailing torque" nuts. The nuts > don't vibrate off, but the pulses often break a stud. That combined with the exhaust system flexing as the engine torques on its mounts, of course... -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: Mystery Nut--Anyone Identify?
"TeGGeR®" <tegger@tegger.c0m> wrote
> "Elle" <honda.lioness@nospam.earthlink.net> wrote >> I took the exhaust manifold shroud off today. It is >> indeed >> an exhaust manifold nut (with broken-off stud stuck in >> it). >> It's the one nearest the distributor. >> >> I am amazed at how many people (Nasty, Tegger, Eric, >> SoCalMike) nailed this, and with a fuzzy photo, too. What >> a >> phenomenal newsgroup! > > > > Broken studs are very common. I had one too. Mine broke > below the surface > of the head. My mechanic removed it, but wouldn't tell me > how (trade > secret, or so he says...). It was done at the same time as > my head gasket > replacement, so the machine shop that trued the head > probably did it. Mine is broken off at the outer surface of the exhaust manifold. Hopefully "all" I have to do is remove the manifold, and I'll plenty of leftover stud to drill/double-nut/etc. I'm not going to pursue it until I get my new front lower control arm bushings in (knock on wood). Tomorrow's a big day. Doggone Napa said they had the stud. I go there and they insist it's a 10 mm stud. I didn't have the broken nut-stud with me and bought it. Back I go. > The problem is that exhaust pulses are quite violent. This > is the reason > you need heat-resistant "prevailing torque" nuts. The nuts > don't vibrate > off, but the pulses often break a stud. > > Funny, the one that broke on mine was the one nearest the > timing belt. It > must be a random thing. Interesting. Maybe I'll see about replacing all nine or so, before they break within the cylinder head. Thanks for the info. As always, it's very helpful. |
Re: Mystery Nut--Anyone Identify?
"TeGGeR®" <tegger@tegger.c0m> wrote
> "Elle" <honda.lioness@nospam.earthlink.net> wrote >> I took the exhaust manifold shroud off today. It is >> indeed >> an exhaust manifold nut (with broken-off stud stuck in >> it). >> It's the one nearest the distributor. >> >> I am amazed at how many people (Nasty, Tegger, Eric, >> SoCalMike) nailed this, and with a fuzzy photo, too. What >> a >> phenomenal newsgroup! > > > > Broken studs are very common. I had one too. Mine broke > below the surface > of the head. My mechanic removed it, but wouldn't tell me > how (trade > secret, or so he says...). It was done at the same time as > my head gasket > replacement, so the machine shop that trued the head > probably did it. Mine is broken off at the outer surface of the exhaust manifold. Hopefully "all" I have to do is remove the manifold, and I'll plenty of leftover stud to drill/double-nut/etc. I'm not going to pursue it until I get my new front lower control arm bushings in (knock on wood). Tomorrow's a big day. Doggone Napa said they had the stud. I go there and they insist it's a 10 mm stud. I didn't have the broken nut-stud with me and bought it. Back I go. > The problem is that exhaust pulses are quite violent. This > is the reason > you need heat-resistant "prevailing torque" nuts. The nuts > don't vibrate > off, but the pulses often break a stud. > > Funny, the one that broke on mine was the one nearest the > timing belt. It > must be a random thing. Interesting. Maybe I'll see about replacing all nine or so, before they break within the cylinder head. Thanks for the info. As always, it's very helpful. |
Re: Mystery Nut--Anyone Identify?
"TeGGeR®" <tegger@tegger.c0m> wrote
> "Elle" <honda.lioness@nospam.earthlink.net> wrote >> I took the exhaust manifold shroud off today. It is >> indeed >> an exhaust manifold nut (with broken-off stud stuck in >> it). >> It's the one nearest the distributor. >> >> I am amazed at how many people (Nasty, Tegger, Eric, >> SoCalMike) nailed this, and with a fuzzy photo, too. What >> a >> phenomenal newsgroup! > > > > Broken studs are very common. I had one too. Mine broke > below the surface > of the head. My mechanic removed it, but wouldn't tell me > how (trade > secret, or so he says...). It was done at the same time as > my head gasket > replacement, so the machine shop that trued the head > probably did it. Mine is broken off at the outer surface of the exhaust manifold. Hopefully "all" I have to do is remove the manifold, and I'll plenty of leftover stud to drill/double-nut/etc. I'm not going to pursue it until I get my new front lower control arm bushings in (knock on wood). Tomorrow's a big day. Doggone Napa said they had the stud. I go there and they insist it's a 10 mm stud. I didn't have the broken nut-stud with me and bought it. Back I go. > The problem is that exhaust pulses are quite violent. This > is the reason > you need heat-resistant "prevailing torque" nuts. The nuts > don't vibrate > off, but the pulses often break a stud. > > Funny, the one that broke on mine was the one nearest the > timing belt. It > must be a random thing. Interesting. Maybe I'll see about replacing all nine or so, before they break within the cylinder head. Thanks for the info. As always, it's very helpful. |
Exhaust Manifold Stud Replacement Questions [was Re: Mystery Nut--Anyone Identify?]
What torque should be applied to the exhaust manifold stud
(91 Civic LX, 176k miles) when installing it in the cylinder head? This torque specification does not seem to appear in the service manual or my Chilton's. I see the locking nuts get 23 ft-lbs, so I suppose that's reasonable for the studs, too. Still, perhaps someone here has some more insight or thoughts on what is reasonable here. Also, ISTM I should replace all nine studs. Any good reason not to? "If it ain't broke, don't fix it," is a good rule, but on a car this old, and since broken exhaust manifold studs are fairly common, I think an ounce of prevention may be appropriate here. Your experience on this matter is welcome. I plan to double nut the studs to remove them, being mindful that they are fatigued and could very well break off in an undesirable way. Again, they're 8 mm nominal diameter studs. My Civic yesterday recorded the lowest gas mileage since I started keeping careful records two years ago--36.3 mpg vs. my average of about 40 mpg (higher in late spring and summer). It's never been this low for this time of year. I googled and it certainly seems that the missing nut may be causing an exhaust leak and causing the engine control system to run rich. I am pricing a new exhaust manifold gasket, studs, and nuts locally today. |
Exhaust Manifold Stud Replacement Questions [was Re: Mystery Nut--Anyone Identify?]
What torque should be applied to the exhaust manifold stud
(91 Civic LX, 176k miles) when installing it in the cylinder head? This torque specification does not seem to appear in the service manual or my Chilton's. I see the locking nuts get 23 ft-lbs, so I suppose that's reasonable for the studs, too. Still, perhaps someone here has some more insight or thoughts on what is reasonable here. Also, ISTM I should replace all nine studs. Any good reason not to? "If it ain't broke, don't fix it," is a good rule, but on a car this old, and since broken exhaust manifold studs are fairly common, I think an ounce of prevention may be appropriate here. Your experience on this matter is welcome. I plan to double nut the studs to remove them, being mindful that they are fatigued and could very well break off in an undesirable way. Again, they're 8 mm nominal diameter studs. My Civic yesterday recorded the lowest gas mileage since I started keeping careful records two years ago--36.3 mpg vs. my average of about 40 mpg (higher in late spring and summer). It's never been this low for this time of year. I googled and it certainly seems that the missing nut may be causing an exhaust leak and causing the engine control system to run rich. I am pricing a new exhaust manifold gasket, studs, and nuts locally today. |
Exhaust Manifold Stud Replacement Questions [was Re: Mystery Nut--Anyone Identify?]
What torque should be applied to the exhaust manifold stud
(91 Civic LX, 176k miles) when installing it in the cylinder head? This torque specification does not seem to appear in the service manual or my Chilton's. I see the locking nuts get 23 ft-lbs, so I suppose that's reasonable for the studs, too. Still, perhaps someone here has some more insight or thoughts on what is reasonable here. Also, ISTM I should replace all nine studs. Any good reason not to? "If it ain't broke, don't fix it," is a good rule, but on a car this old, and since broken exhaust manifold studs are fairly common, I think an ounce of prevention may be appropriate here. Your experience on this matter is welcome. I plan to double nut the studs to remove them, being mindful that they are fatigued and could very well break off in an undesirable way. Again, they're 8 mm nominal diameter studs. My Civic yesterday recorded the lowest gas mileage since I started keeping careful records two years ago--36.3 mpg vs. my average of about 40 mpg (higher in late spring and summer). It's never been this low for this time of year. I googled and it certainly seems that the missing nut may be causing an exhaust leak and causing the engine control system to run rich. I am pricing a new exhaust manifold gasket, studs, and nuts locally today. |
Re: Exhaust Manifold Stud Replacement Questions [was Re: MysteryNut--Anyone Identify?]
Elle wrote: > > What torque should be applied to the exhaust manifold stud > (91 Civic LX, 176k miles) when installing it in the cylinder > head? This torque specification does not seem to appear in > the service manual or my Chilton's. > > I see the locking nuts get 23 ft-lbs, so I suppose that's > reasonable for the studs, too. Still, perhaps someone here > has some more insight or thoughts on what is reasonable > here. > Studs should have slightly more torque than nuts as it is desired that the nut turn freely (when loosening) while the stud remains in place. this can be done by locking two nuts together when installing the stud. Using "lock tight" is also a possibility but may not be as effective due to the high heat this application must endure. > Also, ISTM I should replace all nine studs. Any good reason > not to? "If it ain't broke, don't fix it," is a good rule, > but on a car this old, and since broken exhaust manifold > studs are fairly common, I think an ounce of prevention may > be appropriate here. Your experience on this matter is > welcome. > Yes, I would replace all of 'em if it is not a big hassle. > I plan to double nut the studs to remove them, being mindful > that they are fatigued and could very well break off in an > undesirable way. > That's ok. Just be patient and work the studs in both directions to gradually loosen 'em up. Also, a direct blow or two to the top of the stud itself can be beneficial. Just make sure a nut is present to protect the threads. > Again, they're 8 mm nominal diameter studs. > > My Civic yesterday recorded the lowest gas mileage since I > started keeping careful records two years ago--36.3 mpg vs. > my average of about 40 mpg (higher in late spring and > summer). It's never been this low for this time of year. I > googled and it certainly seems that the missing nut may be > causing an exhaust leak and causing the engine control > system to run rich. > Ethanol mix maybe?? > I am pricing a new exhaust manifold gasket, studs, and nuts > locally today. |
Re: Exhaust Manifold Stud Replacement Questions [was Re: MysteryNut--Anyone Identify?]
Elle wrote: > > What torque should be applied to the exhaust manifold stud > (91 Civic LX, 176k miles) when installing it in the cylinder > head? This torque specification does not seem to appear in > the service manual or my Chilton's. > > I see the locking nuts get 23 ft-lbs, so I suppose that's > reasonable for the studs, too. Still, perhaps someone here > has some more insight or thoughts on what is reasonable > here. > Studs should have slightly more torque than nuts as it is desired that the nut turn freely (when loosening) while the stud remains in place. this can be done by locking two nuts together when installing the stud. Using "lock tight" is also a possibility but may not be as effective due to the high heat this application must endure. > Also, ISTM I should replace all nine studs. Any good reason > not to? "If it ain't broke, don't fix it," is a good rule, > but on a car this old, and since broken exhaust manifold > studs are fairly common, I think an ounce of prevention may > be appropriate here. Your experience on this matter is > welcome. > Yes, I would replace all of 'em if it is not a big hassle. > I plan to double nut the studs to remove them, being mindful > that they are fatigued and could very well break off in an > undesirable way. > That's ok. Just be patient and work the studs in both directions to gradually loosen 'em up. Also, a direct blow or two to the top of the stud itself can be beneficial. Just make sure a nut is present to protect the threads. > Again, they're 8 mm nominal diameter studs. > > My Civic yesterday recorded the lowest gas mileage since I > started keeping careful records two years ago--36.3 mpg vs. > my average of about 40 mpg (higher in late spring and > summer). It's never been this low for this time of year. I > googled and it certainly seems that the missing nut may be > causing an exhaust leak and causing the engine control > system to run rich. > Ethanol mix maybe?? > I am pricing a new exhaust manifold gasket, studs, and nuts > locally today. |
Re: Exhaust Manifold Stud Replacement Questions [was Re: MysteryNut--Anyone Identify?]
Elle wrote: > > What torque should be applied to the exhaust manifold stud > (91 Civic LX, 176k miles) when installing it in the cylinder > head? This torque specification does not seem to appear in > the service manual or my Chilton's. > > I see the locking nuts get 23 ft-lbs, so I suppose that's > reasonable for the studs, too. Still, perhaps someone here > has some more insight or thoughts on what is reasonable > here. > Studs should have slightly more torque than nuts as it is desired that the nut turn freely (when loosening) while the stud remains in place. this can be done by locking two nuts together when installing the stud. Using "lock tight" is also a possibility but may not be as effective due to the high heat this application must endure. > Also, ISTM I should replace all nine studs. Any good reason > not to? "If it ain't broke, don't fix it," is a good rule, > but on a car this old, and since broken exhaust manifold > studs are fairly common, I think an ounce of prevention may > be appropriate here. Your experience on this matter is > welcome. > Yes, I would replace all of 'em if it is not a big hassle. > I plan to double nut the studs to remove them, being mindful > that they are fatigued and could very well break off in an > undesirable way. > That's ok. Just be patient and work the studs in both directions to gradually loosen 'em up. Also, a direct blow or two to the top of the stud itself can be beneficial. Just make sure a nut is present to protect the threads. > Again, they're 8 mm nominal diameter studs. > > My Civic yesterday recorded the lowest gas mileage since I > started keeping careful records two years ago--36.3 mpg vs. > my average of about 40 mpg (higher in late spring and > summer). It's never been this low for this time of year. I > googled and it certainly seems that the missing nut may be > causing an exhaust leak and causing the engine control > system to run rich. > Ethanol mix maybe?? > I am pricing a new exhaust manifold gasket, studs, and nuts > locally today. |
Re: Exhaust Manifold Stud Replacement Questions [was Re: Mystery Nut--Anyone Identify?]
"Grumpy AuContraire" <Grumpster@GrumpyvilleNOT.com> wrote
> Elle wrote: >> >> What torque should be applied to the exhaust manifold >> stud >> (91 Civic LX, 176k miles) when installing it in the >> cylinder >> head? This torque specification does not seem to appear >> in >> the service manual or my Chilton's. >> >> I see the locking nuts get 23 ft-lbs, so I suppose that's >> reasonable for the studs, too. Still, perhaps someone >> here >> has some more insight or thoughts on what is reasonable >> here. >> > > Studs should have slightly more torque than nuts as it is > desired that > the nut turn freely (when loosening) while the stud > remains in place. > this can be done by locking two nuts together when > installing the stud. > Using "lock tight" is also a possibility but may not be as > effective due > to the high heat this application must endure. > > > >> Also, ISTM I should replace all nine studs. Any good >> reason >> not to? "If it ain't broke, don't fix it," is a good >> rule, >> but on a car this old, and since broken exhaust manifold >> studs are fairly common, I think an ounce of prevention >> may >> be appropriate here. Your experience on this matter is >> welcome. >> > > Yes, I would replace all of 'em if it is not a big hassle. > > > >> I plan to double nut the studs to remove them, being >> mindful >> that they are fatigued and could very well break off in >> an >> undesirable way. >> > > That's ok. Just be patient and work the studs in both > directions to > gradually loosen 'em up. Also, a direct blow or two to > the top of the > stud itself can be beneficial. Just make sure a nut is > present to > protect the threads. Sounds good. My parts are on order locally and I think I'll work on this before my pass. side front bushings. I'm going to soak as much as I can of the applicable bolt threads in PB Blaster today. Fortunately I had the header pipe disconnected from the exhaust manifold a couple of years ago. Thanks for sharing your experience, JT. >> Again, they're 8 mm nominal diameter studs. >> >> My Civic yesterday recorded the lowest gas mileage since >> I >> started keeping careful records two years ago--36.3 mpg >> vs. >> my average of about 40 mpg (higher in late spring and >> summer). It's never been this low for this time of year. >> I >> googled and it certainly seems that the missing nut may >> be >> causing an exhaust leak and causing the engine control >> system to run rich. >> > > Ethanol mix maybe?? No. I am using the same gas stations I usually use. They haven't shifted. Last time I did get a winter mix, I didn't notice a change in fuel mileage (using odometer miles/gallons added to top off). |
Re: Exhaust Manifold Stud Replacement Questions [was Re: Mystery Nut--Anyone Identify?]
"Grumpy AuContraire" <Grumpster@GrumpyvilleNOT.com> wrote
> Elle wrote: >> >> What torque should be applied to the exhaust manifold >> stud >> (91 Civic LX, 176k miles) when installing it in the >> cylinder >> head? This torque specification does not seem to appear >> in >> the service manual or my Chilton's. >> >> I see the locking nuts get 23 ft-lbs, so I suppose that's >> reasonable for the studs, too. Still, perhaps someone >> here >> has some more insight or thoughts on what is reasonable >> here. >> > > Studs should have slightly more torque than nuts as it is > desired that > the nut turn freely (when loosening) while the stud > remains in place. > this can be done by locking two nuts together when > installing the stud. > Using "lock tight" is also a possibility but may not be as > effective due > to the high heat this application must endure. > > > >> Also, ISTM I should replace all nine studs. Any good >> reason >> not to? "If it ain't broke, don't fix it," is a good >> rule, >> but on a car this old, and since broken exhaust manifold >> studs are fairly common, I think an ounce of prevention >> may >> be appropriate here. Your experience on this matter is >> welcome. >> > > Yes, I would replace all of 'em if it is not a big hassle. > > > >> I plan to double nut the studs to remove them, being >> mindful >> that they are fatigued and could very well break off in >> an >> undesirable way. >> > > That's ok. Just be patient and work the studs in both > directions to > gradually loosen 'em up. Also, a direct blow or two to > the top of the > stud itself can be beneficial. Just make sure a nut is > present to > protect the threads. Sounds good. My parts are on order locally and I think I'll work on this before my pass. side front bushings. I'm going to soak as much as I can of the applicable bolt threads in PB Blaster today. Fortunately I had the header pipe disconnected from the exhaust manifold a couple of years ago. Thanks for sharing your experience, JT. >> Again, they're 8 mm nominal diameter studs. >> >> My Civic yesterday recorded the lowest gas mileage since >> I >> started keeping careful records two years ago--36.3 mpg >> vs. >> my average of about 40 mpg (higher in late spring and >> summer). It's never been this low for this time of year. >> I >> googled and it certainly seems that the missing nut may >> be >> causing an exhaust leak and causing the engine control >> system to run rich. >> > > Ethanol mix maybe?? No. I am using the same gas stations I usually use. They haven't shifted. Last time I did get a winter mix, I didn't notice a change in fuel mileage (using odometer miles/gallons added to top off). |
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