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Advice on torquing exhaust manifold bolt that keeps loosening (Stripped Threads)

EfiniX

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portland, or
Or rather a bolt. I know it's supposed to be torqued to 13'lbs, but with the heat wrap on the manifold, I can't get a socket on the bolt. I've tightened it by hand twice since installation and that bolt keeps running itself out. I'm thinking about putting a locking washer on, but EHMotorsports pointed out that the heat typically invalidates any real benefit in short order. So...

...tightening by hand with a 7" wrench. Just how tight should it be? Get it snug, then a quarter turn? 2/5ths? 3/5ths? They are new ARP studs, but that's because a few of the stock bolts were broken after the last round of work. That day sucked and I'm not looking to repeat it.
 
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coyotes

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Are you talking about the studs to the head or the bolts that connect the manifold to the turbo? The nuts to the head I used ratchet wrenches. If you can't get a socket on it maybe try a 1/4" drive socket? Which one can't you reach, is it the one by the power steering pump? You gotta remove the bracket to have room to get to it (although I was able to remove the nut with a 1/4" drive socket on a universal joint)
 
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EfiniX

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portland, or
I'm talking about the nuts that go on the exhaust manifold studs in the head. Evan and I replaced those studs with ARP studs about a month ago. I've just recently noticed that one of the nuts has walked itself off the stud. Fortunately it hasn't fallen completely off the stud due to the heat wrap actually holding it in place at the end of the stud. Thank goodness for small miracles, the bolt that's running out is the top-left, arguably the easiest to get to. Thing is, I can't get a socket on the bolt because of the heat wrap meaning I can't get my torque wrench on it. Even if I could push/pull/squish the heat wrap down a bit to get a socket on, that tension would throw the torque wrench off.

Breaking an exhaust bolt is a nightmare, so I'm looking for a little advice on guessing at 13'lbs using a 1/2" wrench. I've actually tightened it twice now, and it's run off within a day each time. I'll probably throw a locking washer on it because why not, but I'm very nervous about putting too much torque on that nut and breaking the stud.
 
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coyotes

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I think you'd be ok if you estimate and just use common sense when tightening down, you have worked on cars enough to *know* when something is properly tight. I would say put a small dab of locktite on it or try putting a second nut on top of the first if there is room. Perhaps it is not tight enough if it keeps backing off? I have not seen exhaust manifold nuts back off like that before.

Or buy a crow foot wrench and put your torque wrench on it.
 
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mitsuturbo

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Jun 2, 2008
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Exh mani nuts should be checked periodically after initially torquing them down. Especially if you're using a copper gasket, or one of the composite ones that seem to be so prevalent in the cheaper gasket kits. Even with the mitsu MLS i check mine every so often and make sure they're tight, even though these seem to exhibit less "crush" characteristics and seem to lend less to the nuts going loose. I'm running a copper gasket now and after a few miles they were all a bit on the loose side. Clamped it down some more and not all seems well.
 

prove_it

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How old is your manifold? I wonder if it has some warping happening causing the nut to work off. It seems odd that it's come loose twice when all others haven't.

Could be just not tight enough, but 13 lbs/ft torque is very low and achievable by hand easily. Now your sure it's the nut coming loose and not the stud moving out right? Otherwise, tighten to snug then go about a 1/3 turn and that should put you around 15 lbs/ft torque.
 

EfiniX

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portland, or
Ah, this!
Manifold is an FP with 5000 miles on a head with the same. Copper gasket (if memory serves). The stud isn't any further out then its neighbors, so I think I'll put a locking washer on it and give it a 1/3rd turn.

Thanks!
 

EfiniX

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portland, or
Ok. I couldn't get the old nut off without pulling the manifold off the head due to clearance issues. No worries, thigh. I just torqued it down harder and scribed the end of the stud. If it comes loose again I should be able to tell if the stud has turned.

Fingers crossed...
 

prove_it

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Good plan. Best of luck.
 

Street Surgeon

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Omaha, Nebraska
Use nordlocks, add 20% more tq when tightening (if you can't get a socket or crows foot on it just german gut-n-tight it) and you're done, they won't back off.
 

tektic

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ronkonkoma, ny
Are you using the factory copper locking nuts?

I have not had issues with theses /ubbthreads/images/graemlins/dunno.gif
 

prove_it

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FWIW, I've had the same set of stainless steel studs with washer, lock ring, and nut. Haven't had a single issue in 20k miles.
 

467

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Mar 16, 2001
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Fremont Ca
Exhaust Manifold nuts - 18 to 22 ft./lbs. A 7 in wrench is about 1/2 foot from the nut to near the end of the wrench your pushing on. Push perpendicular to the the wrench with about 36 lbs of force. Calibrate your fingers or hand against a scale to get a feel for pushing 36 lbs just before you tighten. Or, if you have a fish scale type device pull perpendicularly on the end of the wrench with a line to the scale if you have room.
 

G

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Feb 24, 2004
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zompton
Quoting tektic:
Are you using the factory copper locking nuts?

I have not had issues with theses /ubbthreads/images/graemlins/dunno.gif



Mitsubishi never offered factory copper nuts.
 

prove_it

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Sioux Falls, SD
What?
 

SleepinGVR4

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Feb 12, 2003
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Danville, Pennsylvania
Quoting G:
Quoting tektic:
Are you using the factory copper locking nuts?

I have not had issues with theses /ubbthreads/images/graemlins/dunno.gif



Mitsubishi never offered factory copper nuts.



Wrong.
 

EfiniX

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Oct 18, 2012
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647
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portland, or
Well it ran itself out again, so I gave a good, strong twist in the parking lot of the airport. The scribe mark on the stud hasn't turned, so I don't thing it's running itself out. If it happens again, I'm going to cut the end of the stud off so I can run the nut off (without having to loosen the whole manifold) and swap it with a locking nut.
 

coyotes

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If you're manly enough, drill a hole through the nut and stud and safety wire it. /ubbthreads/images/graemlins/grin.gif
 

prove_it

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Are you using lock washers? That might do the trick.
 

EfiniX

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portland, or
Quoting coyotes:
If you're manly enough, drill a hole through the nut and stud and safety wire it. /ubbthreads/images/graemlins/grin.gif



Safety wire won't keep the nut tight. It's just there to keep it from falling off and onto the road surface if it comes loose. Unfortunately, the manifold is doing that now.

And I'm fairly sure that I'm not using a lock washer. That will change if it comes loose again.
 
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