exhaust/ intake manifold stud sheared

I have a stud broken off the exhaust manifold that bolts the intake/exhaust manifolds together...I did a search thinking this would have already been covered but couldn't come up with anything. I have ground the broken stud flat and started drilling it out, but before I go too far does anyone have any input on how to replace this stud? I appreciate any input on this subject.

Terrell
Columbia, Mo

If you are drilling make absolutely sure you are drilling in the center of the broken stud. Try a little rusty thread solvent like MOOVIT after applying heat with a propane torch. I have and like reverse the drill bits I bought from Snap-on. Do not be in a hurry, the stud could be very hard from heat cycling. A drill press is a better choice than handheld. I am fortunate to have a milling machine and centre cut end Mills in carbide.
One thread solvent is as good as any other. A little
is a ll that is needed. If it is running off onto the floor you are wasting product.
If you can afford the little extra cost, take both manifolds to a machine shop for truei.ng and matching.

Terrell,
As you've already discovered, exhaust system fasteners take a beating from all the hot/cold cycles and corrosion from the exhaust.
If the stud was threaded in the piece you are working on then yes you have to drill out and hopefully save the threads.
The first drill attempt is the most important as it has to be centered as best you can. And at a perfect right angle! I use a tiny square.
I always start with a smaller sharp bit like an 1/8" or so and work up.
You know you are doing things right when you just end up with the remnants of threads of the old stud in the threads of the piece you are working on.
There's nothing wrong with stopping here and there and trying an "easy out" bolt extractor. My guess is that won't work.
A drill press really comes in handy here if you can hold the piece so the broken stud is perfectly parallel to the drill.
Good luck!
Use cutting oil of some kind. The coated "HF" drill sets work good on this stuff once or twice before being junk.

I understand the comment, "The coated "HF" drill sets work good on this stuff once or twice before being junk." I have had more than a few of these cheepo bits twist from a spiral flute to a straight flute.
Correct stud removal is critical at this time. It is very unlikely another suitable manifold can be found and if there is a good one, it could cost hundreds of dollars. These cheepo bits cannot be resharpened.
You, Monsonmotors, have a lifetime of experience and have developed a feel for this difficult drill-out. I recommended using a machine shop because I do not know the level of experience the OP has.

Thanks for the input. I am using my drill press to drill the hole( made a wood cradle to support the manifold while on the drill press base), center punched the hole in the exact center of the broken stud. It has been heated several time and allowed to cool, a ez-out wouldn't budge the stud, it has been soaking for several days( put a small squirt on it ever time I pass by the drill press). My real question is this stud, does it just bottom out in a hole that doesn't go all the way thru the manifold and is something special that locks it self into place?
After the stud is removed and replaced I will weld where I found a small crack, in the same area of the broken stud, I have already drilled stop holes at all three ending points of the crack and ground thru where the crack was to prepare for welding, and will sandblast the area to clean it up... Unfortunately I have pitched my old bbq barrel type of grill the I used in the past to heat up cast pieces to be welded, then after the weld bury the piece in sand on a plate placed in the grill on top of the coals to allow for a slow cool down period( I also covered the bbq grill with a welding blanket). I plan on using this same method to weld this manifold, any suggestions or additional steps? As you have already stated these are almost impossible to find in any condition.....I do not want to make it a bigger job that it already is!
The only thing I have to add is that this time, my barrel grill will not be pitched, no matter how much harping my wife does for keeping a grill that is almost never used,,,,does anyone else has this same issue or is it only me????

Thanks,
Terrell

Terrel
I would follow Monsommoters in stepping up in drill sizes.
It appears you are proceeding so here are a few suggestions.
Use the depth of the other holes as a guide for drilling depth. If all the other holes are a consistant depth chances are the broken bolt is the same. Also use the length of a good bolt as a gauge with the thickness of the manafold to see how close they are to bottoming out.. The should not be bottoming out.
Put a collar or some tape on the bit to know where to stop drilling.
Each time you drill the bolt heating it will be easier as the walls get thinner.
When you get up to a 1/4 bit you will only have a 1/16 wall left The next bit size would be the size used for tapping a 3/8 bolt hole. You will see how well your centered when you get to that 1/4 bit.
A propane is being caeful with the heat. After you hrill the 1/4 hole. in my opinion you could get a oxy/accet torch and concentrate it on the broken stud and it will heat up fast enough to not damage the head. Preheat the cast iron sorrounding the bolt a little first.
When you get that 1/4 hole drilled and you dont feel comfortable going up in size or if its not centered well enough work with it a little. after you heat put a sharp edge on an old screwdriver and try to catch the edge of the drilled hole tapping in the counterclockwise direction.
Aso sometomes you can tell when your drill is breaking thru the bottom of the bolt because the bit will hang up like it does with going any steel. Ihe ideal depth is for the bit to just break thru at the tip. Then that oil can get in there.
I would tig the crack. If its non structural sonetimes you can grind a little v and braze the crack. After re reading it sounds like you have the welding figured out. With those cracks being close you may want to weld first. Your drilled stop holes should make it ok.
i drilled a stop hole in a plexiglass boat windshield once. It created a sun magnifier and burned a hole in the dash.
To answer your question . a bolt that bottoms out is useless as a bolt. It cant tighten up ,and it doesnt go through to anything else.
Just stuck. Heat and lubrication are ypur best freind here. Itt will come loose with patience. unless time is urgent. If you didn't have those cracks a few sharp snaps with a punch and a hammer are effective.
Mike

Mike and Monson X 2.

I would add this. I've had good luck with reverse turning bolt extractors if the extractor is the correct size for the hole you have drilled in the stuck bolt. If you've drilled to 1/4 inch, there should be precious little left holding the bolt in the head. You can find a chart on line. Google is your friend, or so I'm told. Failing that, a heli-coil kit may be in your future.

John
Ya . I would be interested in a really good set of extractors. I had one good set that held tight that weren't brittle. They have to be harder than the bolt but the cheap ones break very easy. Buy the best you can get. I would work it over good and then use the extractor/easy out.
Does anyone have a good brand name? Theres so much junk out there. Maybe Napa has the good quality. Dont force the extractor too much. I have broke them expecting too much
Mike
Terrel
Can you show pictures of the cracks.

I went back and looked at my older posts, and I also had a manifold bolt shear. The pictures are at
viewtopic.php?f=8&t=5359&p=40406#p40406
To be honest, I do not recall how I got the bolt out. I dont recall taking it to my machinist friend, so who knows. Maybe I drilled it myself. Maybe my friend welded a nut to it and it came out.

Just wanted to share the pictures.

John
Ya . I would be interested in a really good set of extractors. I had one good set that held tight that weren't brittle. They have to be harder than the bolt but the cheap ones break very easy. Buy the best you can get. I would work it over good and then use the extractor/easy out.
Does anyone have a good brand name? Theres so much junk out there. Maybe Napa has the good quality. Dont force the extractor too much. I have broke them expecting too much
Mike
Terrel
Can you show pictures of the cracks.

They do break. They will break if the drilled hole isn't deep enough and /or the drilled hole is too small for the broken bolt to be removed. Too small a hole requires a small diameter extractor. The bigger the hole the bigger the extractor. My best results come when I drill just shy of bottoming out, and progressively enlarge the hole to a tad less than the diameter of the broken bolt/stud. The extractor will only grab if it is the correct fit for the drilled hole.