Broken exhaust stud removal

[JHZR2]

Thinking outside the box here. Can you chase the thread down to a smaller size (i.e. #12 at 9.53mm instead of 10mm) and just use a smaller bolt (again #12 at 9.53mm instead of 10mm) to grab that specific one (i.e. a bolt that is less than 1mm smaller like going between metric and English unit), and leave the old stud in place?

Or, find a used manifold in the junkyard or eBay and just replace it? I know you want to save what you have and know the history of but sometimes you have to pick your battle and find an alternative.

That’s a really interesting idea if the wax and whatnot doesn’t work.

The studs aren’t 10mm I don’t think, they’re M8x1.25.

So I’d need to determine what that stock can be cut down to, I’m thinking with the same thread pitch as original.

 

[CleanSump]

I've cut off a grade 8 or Bowman Bomaloy bolt and tapped to match the bolt threads. That way you know the smaller diameter stud is more than strong enough.

 

[JHZR2]

I’m partway there but afraid I’m more screwed than before.

I did apply mapp gas and quenched the stud, went slowly both directions, with some gonna penetrant oil applied and two came out. One broke part way, and the other broke below the surface.

Ugh.

The one that broke part way is in a blind hole. I can’t see the backside. I can’t grip it even with Malco eagle grip vice grips. The broken stud isn’t long enough for any kind of extractor to get purchase.


The one that is broken below the surface is not a blind hole. I’m sure I can drill it. But can I do so without damaging anything or breaking something else off?!? Not so sure. If I break a carbide anything off there I’m done. It took a LOT of force with an 18” 1/2 ratchet to get the two out that I did. More than I can apply with anything else practically speaking, especially any sort of extractor.


I know, get a welder. Learn to weld and get a nut on the stud that’s sticking out. Got it. Maybe for both.

Would a flux welder work? How do I best practice before actually doing it???!?

 

[Pablo]

I’m partway there but afraid I’m more screwed than before.

View attachment 335920

I did apply mapp gas and quenched the stud, went slowly both directions, with some gonna penetrant oil applied and two came out. One broke part way, and the other broke below the surface.

Ugh.

The one that broke part way is in a blind hole. I can’t see the backside. I can’t grip it even with Malco eagle grip vice grips. The broken stud isn’t long enough for any kind of extractor to get purchase.


The one that is broken below the surface is not a blind hole. I’m sure I can drill it. But can I do so without damaging anything or breaking something else off?!? Not so sure. If I break a carbide anything off there I’m done. It took a LOT of force with an 18” 1/2 ratchet to get the two out that I did. More than I can apply with anything else practically speaking, especially any sort of extractor.


I know, get a welder. Learn to weld and get a nut on the stud that’s sticking out. Got it. Maybe for both.

Would a flux welder work? How do I best practice before actually doing it???!?

Reverse drill bits and usage. Look that up

 

[Pablo]

I’ve been there. You’re gonna be fine.

Do you have a Dremel tool? Buy a set of diamond bits.

Don’t try a conventional easy out. It will break and if you drill it out be careful in picking a good strong starting size that has minimal chance of breaking and not too large to contact female thread

Worst case you will need to run a tap in the hole which will be easy.

 

[spasm3]

I did apply mapp gas and quenched the stud, went slowly both directions, with some gonna penetrant oil applied and two came out. One broke part way, and the other broke below the surface.




I know, get a welder. Learn to weld and get a nut on the stud that’s sticking out. Got it. Maybe for both.

Would a flux welder work? How do I best practice before actually doing it???!?

My worry is you mentioned stainless. If those are really stainless and you got them good and hot with mapp gas, they are going to be hardened and difficult to drill. Even cobalt m42 bits may have trouble drilling through that, and you will have to go slow.

I think a flux welder should work fine. That's the best approach at this point. The heat from welding a nut on often loosens the corrosion bonds.

 

[Pablo]

Stainless can be annealed if heated around 2000°F and quenched

How do we know this is stainless steel?

If a very much harder tool breaks it still can be ground out with a diamond bit. It’s not that difficult

I would try the reverse drill bits first

 

[JHZR2]

Stainless can be annealed if heated around 2000°F and quenched

How do we know this is stainless steel?

If a very much harder tool breaks it still can be ground out with a diamond bit. It’s not that difficult

I would try the reverse drill bits first

It’s certainly not magnetic.

And then nuts came off super easy when taking everything apart. Very clean.

And, unfortunately I’m breaking every cobalt bit I have…

 

[Pablo]

It’s certainly not magnetic.

And then nuts came off super easy when taking everything apart. Very clean.

And, unfortunately I’m breaking every cobalt bit I have…

Yeah it’s also work hardened it sounds like. Diamond bits. The round ball kind work well

 

[JHZR2]

Yeah it’s also work hardened it sounds like. Diamond bits. The round ball kind work well

I have a dremel, but shouldn’t I just chuck it into a drill?

 

[Pablo]

I have a dremel, but shouldn’t I just chuck it into a drill?

Dremel easier to control and zero need to bear down

https://a.co/d/07UkrQOC

 

[Pablo]

The diamond and hard debris should make a little pool of extremely abrasive material that will do the cutting. Bearing down just wears the bit. Don’t remove the junk as you grind

 

[JHZR2]

Nothing is getting through and I’ve broken most small bits I had in cobalt M42.

Even the diamond bits.

My arms and everything is shot. Admitting defeat.

 

[Pablo]

Looks like you have holes??

 

[JHZR2]

Looks like you have holes??

They’ve been the exact same holes for 1.5+ hours. And I’ve been attempting to drill the whole time.

 

[Pablo]

They’ve been the exact same holes for 1.5+ hours. And I’ve been attempting to drill the whole time.

You need more diamond bits. Be patient

 

[JHZR2]

You need more diamond bits. Be patient

I got a bunch more. They don’t seem to do much for this. I’m running them on a dremel, low speed, like 2/10 with minimal pressure but oil in the hole. Maybe I’m doing it wrong??

I got some cheap M35 bits figuring that they may get ruined or broken. I have been able to get continuous spirals out of the stud with the blind hole.

The other stud that is actually much shorter and not a blind hole, accessible from both sides, I can’t get to drill at all front or back side. I grated it with diamond for 10+ minutes. No dice.

So I’m nowhere near getting these out. I just waste time. But it’s getting marginally closer for the one.

The other, I have no clue.

 

[Pablo]

I would leave the oil out of it, but you should make some progress. That's crazy! It's probably getting more work hardened.

Try annealing the stubborn one. Heat it, then set an ice cube on it. It only need to reach 2100°F. MAPP gas can get hotter than that. Just and idea to soften it.

 

[JHZR2]

I would leave the oil out of it, but you should make some progress. That's crazy! It's probably getting more work hardened.

Try annealing the stubborn one. Heat it, then set an ice cube on it. It only need to reach 2100°F. MAPP gas can get hotter than that. Just and idea to soften it.

So, I did try that map gas heating a few times actually to get the work hardening out.

In the end, you’re right, keep after it with the diamond ball. Front and rear. Then I hammered a cheap awl through it.

So both are through!!

But they’re both stuck solid.

Now I should be able to get in with more and more left handed cobalt drills.

At what point do I dare an ez out?

 

[CleanSump]

Since I had a '92 300D for 23 years I'm rooting for you.
So what is the plan going forward? Make the holes larger with either the Dremel or hardened drill bits?
A retap for Helicoils and go back to the original size studs?