Broken exhaust manifold stud problems

The engine going into my challenge truck has a broken exhaust manifold to y-pipe stud. I've mostly been tearing it up worse as I've tried to remove it. So far I've:

1. Hitting it with Kroil and PB Blaster, and letting it sit for several days.
2. Heating it up with a torch, and trying to melt candle wax into the threads.
3. Tonight, since I have my welder back, welded a nut to what was left of the stud, and proceeded to successfully break off more of the exhaust stud.

Am I at the point where I should just take an angle grinder to cut it relatively flush, and attack it with drill bits, or is there something else that might work?

Weld new stud to remnants of old stud and use spacer if needed to keep nut down on new threads. All 6 studs on my challenge car are done that way

^ that

Interesting. I'm pretty sure I do not have the skill level to successfully weld a new stud onto a rusty old broken stud, and have it stay lined up, and be strong enough to hold everything together. But, may try it anyway.

If you're skilled you can supposedly burn it out with the smoke wrench and leave the threads intact. Or weld a nut to it. Also try hammering on the edge of the flange near the threads.

Is the manifold currently in or out of the car? If it's out of the car I'd either weld on a stud or bring it to a parts store machine shop and have them drill it out and put new bronze studs in there.

Its out of the car, still on the engine, though. I'm concerned if I try to remove the manifold from the engine, I'll be dealing with more broken bolts/studs.

I don't have an oxyacetylene torch at home. Would a MAPP gas torch from the hardware store be hot enough? Of course, I'd need to weld another nut to it (third times a charm) to get something that would be able to be twisted with a wrench.

Sounds like a good excuse for headers? Since it's a stud between the manifold and y-pipe, can you get to the back of it somehow? Can you cut a slot into the flange it's threaded into can weld it up later?

Drill bits.

DrBoost wrote: Drill bits.

Winner!

Drill it out, then try the welder/nut again.

Headers would be nice, but it's a Challenge car, so budget is an issue here. I can get to the back side of the stud with my propane torch and with penetrating oil, but the manifold is such that there's no clearance for a drill to get it from that side (which would be nice, there's even an indentation at the end of the stud that could work to guide the drill bit).

If I drill from the bottom, then weld a nut on, won't I just have weakened the area I am welding enough to just break it again, instead of making it turn? I'll try to get a picture of this thing after work.

From the sound of it, I would be pretty tempted to cut a slit in the thing from the nearest flange edge down to the stud, then heat/pry it apart to let the threads spin. Should be fixable when you need to reinstall, and probably the quickest way to get the thing out of there- but then again I really hate the broken fastener endless drilling game.

Grabbed a few pics on my lunch break.

It's a 10x1.5 thread pattern, and there is probably just enough thread left to put another nut on there:

The red circle shows where the top side of the stud is. Unfortunately, the rest of the manifold prevents a drill from being used from this side:

Oh yeah, its on a small block chevy, if that makes a difference.

A nut? There's enough of that left to get vice grips on!

Personally, if it didn't loosen up and spin with some hurt-your-hands tight vice grips clanked with a hammer, I'd cut the slot and be done. It's rare to have that level of access to something like this.

¯\_(ツ)_/¯ wrote: A nut? There's enough of that left to get vice grips on! Personally, if it didn't loosen up and spin with some hurt-your-hands tight vice grips clanked with a hammer, I'd cut the slot and be done. It's rare to have that level of access to something like this.

Vice grips were part of the original attempts, and didn't really do anything other than mangle the stud.

I'm a little worried about cutting a slot in a cast iron manifold making it less likely to be able to hold onto the replacement stud. Will that actually work? Would that be something done with an angle grinder? I really hate using them inside the garage.

In reply to eastsidemav:

I'd do it with a cutoff wheel on an angle grinder, following the golden rule of "if you can't get a tourniquet on it, don't put it in plane with the death wheel." You'd just be cutting it in towards the threaded hole, it wouldn't be in the sealing surface and shouldn't create any cracks that can propagate. If the stud doesn't want to stay in after replacing it, you can zap a tack weld to the back end and it should never move again- you can grind the weld off if it needs to come out.

Your mileage may vary, of course, but its' worked for me in the past.

Take your MAPP torch and get the stud and area around it glowing red hot (this will take a couple minutes with mapp), then quickly grab it with vise grips, stud tool, or an extractor socket and spin it out.

I've never tried it with a MAPP torch but I can tell you with the confidence of many years of working on cars in the rust belt of upstate NY that if you heat that manifold up red hot that'll come out with a stud tool or vice grips.

Can you just drill it and use a bolt and nut?

EDIT: and if you do end up breaking them off in the head (assuming its aluminum)

https://www.youtube.com/embed/fqZYgReuywM

I had very good luck replacing one with a C clamp on a old Chevy. It ran like that until it went to the junk yard.

There is a company that makes them if you don't want use a plane old C clamp.

Okay, the c-clamp may be my last resort

Picked up a MAPP gas torch and a new welding helmet after work. When I get home from dinner, I will be attacking this thing again.

The first plan will be to weld another nut to the remnants of the stud, then use the torch to try to heat everything up, and try to spin it off with a wrench.

Failing that, I may attack it with an angle grinder.

Toyman01 wrote: I had very good luck replacing one with a C clamp on a old Chevy. It ran like that until it went to the junk yard. There is a company that makes them if you don't want use a plane old C clamp.

If there is room for this there must be room to through bolt it unless im going nuts?

In reply to java230:

Many times there is room for this, but not room for a drill. You can mount a clamp without removing the manifold.

In reply to Toyman01:

Ah that makes perfect sense....

With the MAP Torch take your time and get it cherry red all the way around. Try not to heat the stud directly with the torch as best you can this will cause the surrounding casting to expand just that little bit more than the stud.