broken exhaust stud not cooperating

[oldgeek]

This stud was broken off flush when i got the bike. I figured it would come out fairly easy, but it has not budged. I am at a loss as to what to do. Any ideas what to do from here?

 

[Daddio]

Penetrating oil for a couple hours then heat.

 

[oldgeek]

Penetrating oil for a couple hours then heat.

I have been hitting it with pblaster, and heat...
How much heat should i use?
Should i try to heat the stud, or the block too?

 

[HoughMade]

Block, not stud. Expand the hole. As for how much, that part of the head gets the hottest, so pretty hot.

 

[Daddio]

Heat the aluminum. It expands faster than the steel which should free the stud. As far as how much...I don't have an accurate measure for you. I use mapp gas and get it hot. I wish I had a more scientific answer for you.
If that doesn't work you have two more options:
1. weld a nut on the end and use a wrench (and maybe a cheater) to give you more leverage.
2. Drill out the stud (Slowly, it will be easy to jump over to the head material) with a small drill bit graduating to the original size and re - tap it.

I hope this helps and good luck. Never a fun deal.

 

[oldgeek]

Thanks Guys,

Just the info i needed. I have mapp, and acetyl/oxy...I will use the mapp.

 

[Daddio]

Good choice oxy/acetylene would be too hot in my opinion, but would work to weld a bolt on to the stud.

 

[oldgeek]

Well, i give up! It SHOULD have come right out, as it was just threaded in around a 1/2 inch. So there should still be some good thread in the bottom of the hole.

i just drilled it out the rest of the way, mostly. I was just barely off center...I will chase the threads when i get a tap that is the right size.

it looks to be about an 8 mm? possibly i should tap it out to 5/16"?

 

[vfost]

screw extractors are pretty strong for exactly this reason. Since you have it in there already i would just find a way to put more leverage onto it even if you have to put a wrench on the square part and use a pipe or something for leverage. Heck even if you brake the extractor you're no worse off than you were before right?

 

[oldgeek]

I got it done. Thanks ALL...

Heck even if you brake the extractor you're no worse off than you were before right?

I was very careful not to break the extractor. If you have never have a hardened tap or extractor break on you, trust me you don't want it to happen. I put loads of pressure on the extractor, but it still would not budge.

 

[lhaolpa]

I have some left hand bits that I use to remove the stubborn bolts.The combination of torque removing the steel and the heat built up,they usually break loose. lha

 

[drewpy]

Stick welding a nut on there would have the stud out. No problem .
I do it all the time and it never fails.

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[lhaolpa]

Stick welding a nut on there would have the stud out. No problem .
I do it all the time and it never fails.

Posted via Mobile

That's true,however,if the stud breaks off flush with the surface it's really difficult to weld a nut on,but not impossible. lha

 

[oldgeek]

This one for some reason was not normal. I thought it was going to be easy...I think that was the problem!LOL
I got everything almost perfectly set up. The pilot hole was very near dead center, and was straight in. I was able to shoot penetrant in the void behind the stud. I started with a small extractor, and when that one felt like it might break, I moved up to the medium size, and when that one felt like it would break, i moved up to a bigger one. I tried more penetrant, and heat, and quenching along the way. NO...this one was not normal!

 

[lhaolpa]

Lots of times,I drill out the bolt with larger and larger bits until the threads are left,then with a pick,they can be removed. lha

 

[Shaun Chandler]

The way removing a bolt or nut wth heat works is by upsetting. Alot of people heat things up and try to remove them while they are hot its the expansion and contraction that breaks it loose. What Drewpy said about welding a nut is the best approach because it does two things its heats and it gives you something to hold onto once its cool.

Hmmm I seem to remember agreeing with drewpy not to long ago regarding this same question not sure where that was poted though.

I wouldn't tap it to imperial I would keep it metric save yourself or someone else a headache later and keep everything metric.

Might be less frustration just to drill the stud right out and add a helicoil that way you bring it right back to the original thread size.

Shaun

 

[jayel]

Might be less frustration just to drill the stud right out and add a helicoil that way you bring it right back to the original thread size.

Shaun

yes then you don't have to screw around with one odd sized nut/bolt/screw

 

[drewpy]

you can stick weld slightly rebated studs in alloy heads, the steel builds up and doesn't touch the alloy. A good blast with a larger nut, let it cool and it undo's no problem.

I think the stud is M8 and I've used stainless ones in the resto bike (with copper grease)

 

[oldgeek]

you can stick weld slightly rebated studs in alloy heads, the steel builds up and doesn't touch the alloy. A good blast with a larger nut, let it cool and it undo's no problem.

Speak simple man...way over my head

I was going to see how well the hole cleans up, since there should still be threads in the bottom. If that does not work out, then tap out to a 10mm (I can get a 10mm x 8mm stainless stud to go back in) and if that does not work, then a heilcoil.

 

[bcware]

What sort of drill bit did you use to drill it out as far as you did? I am dealing with a nightmare bolt stuck in the left side of the engine, but all the bits I try seem to just dull.