Broken Exhaust Stud

GotRoad? · 12-19-2005, 10:43 AM

Yesterday when removing my exhaust pipes I broke off one of the header studs. About 1/2 inch is protruding which is not enough to get vice grips on from the side. What is the next best way to get the stud out. I went to Sears to see what tools they might have to get the piece out. One was a cutter bit with a collet that taps into the broken stud & then backs it out. It seems like it might be hard to use. The other piece was some sort of nut that you drive onto the broken studd with a hammer and then use a wrench or socket to back the whole works out. As I've never used either I would appreciate some advice. Also is the thread direction reversed on the end of the stud that screws into the head ? Thanks !

-Craig

repoe3 · 12-19-2005, 10:58 AM

you are on the right track. try wd-40 and other chemicals that might ease the grip the threads have on the bolt. the drill and tap way is low impact, i would try that first.

repoe3

Flatbutt1 · 12-19-2005, 11:51 AM

I've been a broken and exhausted stud for years

maxer900 · 12-19-2005, 12:21 PM

PB Blaster is a great product for lossening stuck bolts. Available from PeP Boys. Let is soak overnight then use a torch to heat the area around the stud before trying to remove it
If there is enough thread sticking out to get two nuts on then you can use one to jam against the other.

Good luck

1100s nut · 12-19-2005, 03:37 PM

Quote:

Originally posted by flatbutt
I've been a broken and exhausted stud for years

Flattbutt, your also a Nut!!! :-)

Lane

RoundelRider · 12-19-2005, 04:17 PM

Have you seen/used one of these stud removers??? You can get them at your local autozone (inexpensive one anyways) Can ya get this on it???

If you can find some get some AeroKroil. This stuff makes PB blaster look silly (and PB is some good stuff) Heat is your friend, if you dont have a oxyaceteline (sp?) torch, a small torch from home deopt with some MAPP gas might work, propane wont get it hot enough.

Can you tighten it back in some? Work it back and forth with smome penetrant and you might get lucky. Worse case is ya have to drill out the brken stud and install a Helicoil.

Ive busted a few exhaust bolts/studs on Hondas, and I feel your pain!

GotRoad? · 12-19-2005, 05:04 PM

RR,
I've seen the stud remover you've shown, but unfortunately it's too big to get into the restricted space where the bolt exits the head. That's most of the problem; getting hold of enough of the piece and getting some leverage to turn it out. For now I'lll keep putting some penetrating oil on the thing and maybe have a go drilling it out and tapping with a bolt extractor. Saturday will be soon enough to try.

Sideshow_S · 08:22 PM

Bolt extractor seem to work for me about 2 out of ten times. The other 8 times they crack off hardened steel into the hole I drilled to tap them into.

If you want my advice, and I find this to work well when you take your time, follow these steps:

You'll need: drill bit set, centering tool, compressed air (optional), a good eye, drill, tap & drill chart, tap that matches the stud's dimensions.\

1. Buy a centering tool for a drill bit. This is important. Failure to use a centering tool will result in helicoils.

2. Either the facing surface of the stud sheared so that drilling it will drill nicely, or it has a big nasty center that will lead a drill bit to the side. If so, use a dremel to assist in making a surface that will allow you to drill out the center of the stud.

3. Start with a small bit. 1/16" is a good one. Use the centering tool over the stud and drill out a pilot hole. Taking your time is key, you need not break the drill bit off in the stud.

4. Work up through drill bit sizes. A 1/8" could follow. To avoid stripping the inside of the bolt, look up the size of the drill that would be used for tapping the size of the bolt that is used in the exhaust. Use a drill bit size that is about .050" less than the drill that would be used for tapping. Use compressed air, if you have it, to clean the hole repeatedly during driling. At this point, the bolt is weak enough that you can start pulling out thread fragments from the stud. If not, use the next size of drill up. Eventually, you will have the first few threads removed and you can get ready to hit them up with a tap.

5. (Re)Tap the exisiting threads to clean them. Double-threading with the hole is bad. Make sure you have the correct start when the tapper hits the metal.

This has worked for me more often than extractors. This method is usually my alternative after extractors break off. Which is a pain b/c you then have to waste more drill bits cleaning out the hardened metal.

davidgiannini · 12-19-2005, 07:54 PM

You could try on of these stud extractors.

RoundelRider · 12-20-2005, 04:46 AM

Quote:

Originally posted by davidgiannini
You could try on of these stud extractors.

Thats what I just posted, and he said he didnt have room to get on it with something like that!!

See above!

repoe3 · 12-20-2005, 05:27 AM

slight thread jack...those stud removers. looks like they work by slipping over the broken stud and you use a wrench to turn the knurled wheel that hoepfully will back the stud out. is that right?

repoe3

roger albert · 12-20-2005, 06:59 AM

Exactly Repoe.

Socketwrench/breaker-bar cams the knurled wheel into the stud.
The work very well when there is sufficient access. I think David posted his pick because that one is much more compact than the elcheapos such as roundel and I have. Might work where ours don't

Anyway, Sideshow's advice and procedure is great. But I'd try at least one thing, which GotRoad mentioned himself. The extactors with internal splines that hammer on and then wrench off. At 1/2" exposed, you might have the room. They work really well, and unlike screw extractors, don't break off so frequently.

If that doesn't work I'd add one variation to Sideshow's writeup. I use left (reverse) twist drillbits when doing this. (or when using the dreaded brittle extractors) The advantage is that the drill is exerting torque to loosen the screw during the process, rather than tightening it. On the very first time I ever did this, and well greater than half the time since, the broken screw or stud back itself off during the process. It works extremely well (though like any remedial measure, not _always_) that I'm shocked more mechs and techs don't use it.

And as was said by others, heat and PBB or other good penetrant is worthwhile. To that, I'll add some sharp raps with a steel hammer, which can shock/break/loosen the hold of corrosion. Hammer-oil-soak, Hammer-oil-soak. Lather rinse and repeat as long as you have patience for. Even 50 cycles over a week will take a lot less time than removing a head and taking it all to a specialist.

If you have to drill, do it like Sideshow councels, only twist left.

davidb2 · 12-20-2005, 04:31 PM

I hammered on the stud, then plug welded a oversized nut on the end. I think I used 110-18 low-high dc straight. Its been a while. But it worked. and if that fails, you can still drill with the lefty bits.

PFFOG · 12-20-2005, 05:07 PM

Quote:

Originally posted by davidb2
I hammered on the stud, then plug welded a oversized nut on the end. I think I used 110-18 low-high dc straight. Its been a while. But it worked. and if that fails, you can still drill with the lefty bits.

What he said, slip a nut over the stud, weld it on and turn it off with a socket. The heat from welding helps loosen it, and the hammering ( not tapping, but a couple of good sharp smacks) almost always loosens a stuck fastener.

Drilling, tapping, stud extractors are the last measure when all else fails.

davidb2 · 12-20-2005, 05:50 PM

and 11018 rod is stronger than uncle Al's breath on christmas eve.

GotRoad? · 12-22-2005, 08:08 AM

Between a heat gun, PB Blaster and a hammer-on bolt grabber that I got at Sears I managed to get the broken exhaust stud out. FYI the studs are 8x1.25 except that the threads are cut more deeply than standard so you need the OEM pieces (only $0.96 ea.; such a deal)) Thanks to all for their suggestions. Merry Xmas & HNY!

roger albert · 12-22-2005, 12:36 PM

Glad you got it.

Those hammer on ones REALLY are good, if you have room to hammer.
I've had great luck with them. Only use the old style brittle easy out types when the break is recessed.

BMW is shockingly reasonable about some little custom parts like that.

Merry xmas and happy riding to you too.

GotRoad? · 12-22-2005, 02:56 PM

OK you gurus:
Now that I have removed the broken exhaust stud & discovered that the OEM pieces are a nominal 8x12.5, but not quite, due to the screwy cut of the OEM thread how advisable, or foolish is it to retap the hole to a standard 8x1.25 ? The reason that I ask is that I have the SJ exhaust inserts which adds to the length the exhaust stud must span, and a slightly longer stud (45 mm vs stcock 40) would be the ticket, and might explain why mine broke off in the first place. So how stupid is it for me to retap the existing (nonstandard) hole with an 8x1.25 tap and then get an 8x125 x45 mm replacment stud (used with a wavewasher, of course). ?

PFFOG · 12-22-2005, 03:04 PM

I find it hard to believe that they used a "non-standard" thread. More than likely the threads have changed due to oxidation/corrosion. I would tap it and make sure you get a good quality stud as they are subject to a lot of stress due to expansion - contraction from the heat.

SergioK · 12-22-2005, 05:08 PM

And be absolutely sure to torque it correctly. If you pass the torque spec, the stud will simply end up breaking off again.