The bit was 17/64. I made a guide for 3/16 and 17/64

I drilled in approximately 5/8" with the 17/64 bit. When I clear the hole and run the 8mm tap I'm only going in about 1/2" with the stud. Is that sufficient?

You should drill the stud out completely. 1/2" ain't much.

I'm afraid of drilling too far. There's 5/8" of thread on the stud itself.

Might work @ 1/2" if the threads are not compromised from the extraction trauma. Might have to shorten it if it's on the allen nut side.

We've all been there.
I had jig similar to the stromski.

Started drilling a small pilot, pulled out the drill bushing to get a good look to see how centered it was, readjusted the jig so that the small bit was perfectly centered, then drilled until I made it through the stud. I could feel that I had cleared the stud and that the stud was not fully bottomed in the head. I had also checked the depth of the hole on another head that had the stud safely removed so I knew when I was a going to reach a maximum.

Since the pilot was perfect, to my eye, I drilled the bigger hole and it worked out so well that I was able to clean out the original threads with a tap and it came out great.
I used a regular tap followed by a bottoming tap. As far as I can tell, the taps cleared out steel and restored the original threads.

McMaster has the bits and drill bushings you need if you've got a buddy with a milling machine to fab the rest of the jig. Or if you just want to buy a few quality bits.

McMaster also has a standard tap (more taper) and bottoming tap, if you want to get the threads all the way down. Stromski kit appears to have just a bottoming tap. I used one with more chamfer before going after it with the bottoming tap.

Good luck

Remember you need to go the correct depth. I went too shallow and my barrel nut didnt have room for the hex bit!

Okay I understand, maybe I have to shorten the one that uses the barrel nut

If you are a little long on a barrel nut stud you can add a washer.

Managed to drill deeper and now the stud is fully seated.
Thanks.

Would one of those hand held induction heaters have worked before the stud broke? Enough clearance here? Maybe it could have worked on the broken stud that was still protruding :confused:

You heat the case or head adjacent to the imbedded threads, not the stud. Hot studs are soft and twist off. Induction heaters don't heat the case/head.

Do I apply lock tight to the new studs during installation?
Thanks

I’d also like to know the consensus on this.

I’ve been told it would be okay, but the torque (of the final fasteners) must be applied before the locktite sets.

And I’ve been told it’s not needed.


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I added red locktite to the new studs. Also, every year I'm loosening / tightening (to spec) the bolts around all the exhaust components. I don't want to have to go through that again!

I sure wouldn't. Plenty of people have had seized nuts where the stud came out instead. Better alternative than the stud snapping!

All I can add is... beg, borrow, steal, 3D-print, or just BUY a jig. I worked on a 72 2.4L MFI engine where the owner complained of an exhaust leak once. It turned out the previous engine-fixer messed up one of these heat exchanger studs, tried to remove drill it w/o a jig, made the hole bigger and unable to support a proper size Timesert, and just faked it with a stud in the head.

The one head was no longer repairable even after it was removed from the engine and welded, it was not able to hold torque. So it had to be replaced. Finding a true 2.4L MFI head was absolutely impossible. A lot of work later, we got a set of heads (all six) for the engine.

Don't do what that guy did.

Should I use some sort of paste to keep the gaskets from falling off when I re install the heat exchangers?
Thanks

Now yer thinkin.

Thanks John, If so what would you recommend?