Broken exhaust stud removal

Ten years ago, but same deal:
https://www.hobby-machinist.com/threads/mislabeled-tap.51632/

In Post #7 he says Irwin was sympathetic and sent him a replacement. Granted, I think they've changed hands by 2026. You might be lucky to get a thick Indian accent you can't understand, but hopefully I'm wrong.

Also interesting how they say they're made in one area and thrown into a bin to be labeled elsewhere. I could see the average laborer accidentally dumping a whole bin and quickly sweeping them up and throwing them into any old bin. Again, let's hope I'm wrong.

Today if you have a pulse and show up 50% of the time you're considered a pretty good employee
 
What a fiasco this turned out to be, all because of sketchy tools it seems that should be premium.
I went back to McMaster and looked at another bottoming tap. Same odd pitch. So it wouldn’t have worked either.

How frustrating!!

If I could thread a helicoil in and get it back out I’d be less concerned. But the fact that a helicoil is a one way fit into a blind hole concerns me.
 
Just out of curiosity I would be tempted to buy one from OSG or Regal to compare.

https://www.mscdirect.com/product/details/58868530
I think I will for curiosity and completeness. I figure I’ll probably remove manifolds on at least one of my 603 diesels. And, if a thread in the block was ever destroyed, I’d have to use a helicoil there, so having an extra $29 bottoming tap that probably won’t decrease much in value over time isn’t the worst thing.


But ready for the next debacle??!?


Two threads Im making new because the studs were seized. Two the studs came out ok, and the threads are still in place.

So I chase the two original threads with a chaser. Go in easily with a little cutting fluid. I want to try my studs from Belmetric. No go. Maybe one full turn.

I can thread the chaser in by hand. The new studs, not in the slightest.

IMG_8565.webp

So then I took one of the old studs I removed from the engine block and tried to thread it in. It barely went but I could turn it one or two. Because it came out with its nut affixed, I turned it in with my 13mm wrench. It went a few turns. Then I tried to remove it. The nut, which was hard enough on the stud to come off with the stud, actually came off when I tried backing the stud out! I double nutted it and it came out but the threads, which looked brand new and fully black oxide coated when I pulled them from the car, definitely got reformed.

IMG_8561.webp


So frustrating. Guessing I can get the studs in with a double nut, and as long as 8mm of engagement happens, guessing it’s ok… but any thoughts on this?

I had used tap magic on the threads of the chaser, and oil on the threads of the studs.
 
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