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Broken exhaust manifold studs.

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@TDC

10+ Year Contributor
456
13
Sep 10, 2012
Nor-Cal, California
Hey guys I have a big problem!! I had an exhaust mani stud break off in my head. So I drilled a hole and used an easy out. The worst possible thing went wrong. the easy out broke off in the stud. So basically I now have a broken stud with a broken easy out in the center. :banghead: How on earth would I go about drilling out the whole stud and easy out? I'm already sure i'm just gonna have to helicoil it. What size helicoil kit would I need to get this done? What kind of drill bit would get the job done? Heres a picture of what I got. :ohdamn:

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Well guys I bought a m8x1.25 helicoil kit with a 21/64 cobalt drill bit. Drilling through the broken extractor and stud almost seem like its doing nothing. I am drilling through another stud that broke off with no extractor and it seems the same. I make very little progress after hours of drilling. I really dont want to spend $30 on a carbide tipped 21/64 drill bit and risking the chance of it not working. My next option I have been considering was to just assemble the car without the 2 exhaust mani studs in and drive to a nearby machine shop and get the work done there. Just take off the exhaust mani and have them do the work. I know machine shops charge by the hour. Does anyone know how long it will take for a machine shop to drill it out and helicoil the one stud hole with the extractor?
 
Couple weeks ago, I had a GM 4.2l L6 come in, 5 broken e mani studs, the mechanics, broke 1 ez out, and 2 others had broken drill bits in them.

I used the weld a nut method to get them out, 30 nuts and about 6 arc welding sticks I had them out. took about 2 hours or so.

3 of the broken studs were below the head casting, the same as yours or a bit deeper.

The head was out of the truck.

No Heli-coils needed, I charged $40 per broken stud.

Figure the shop rate times 2 hours
 
You're going to have to bite the bullet & get carbide tooling if you want to get the broken studs & extractor out. I wouldn't be able to sleep well with broken studs on my car. Ultimately the choice is yours.
 
Couple weeks ago, I had a GM 4.2l L6 come in, 5 broken e mani studs, the mechanics, broke 1 ez out, and 2 others had broken drill bits in them.

I used the weld a nut method to get them out, 30 nuts and about 6 arc welding sticks I had them out. took about 2 hours or so.

3 of the broken studs were below the head casting, the same as yours or a bit deeper.

The head was out of the truck.

No Heli-coils needed, I charged $40 per broken stud.

Figure the shop rate times 2 hours


Thanks for the help! I figure that this is getting out of my hands and would just be better to let a machine shop handle it. 2 hours doesnt sound too bad. Especially just one stud. I plan on drilling through my other stud myself and helicoil it just to save some money.



You're going to have to bite the bullet & get carbide tooling if you want to get the broken studs & extractor out. I wouldn't be able to sleep well with broken studs on my car. Ultimately the choice is yours.


I just don't want to drop $30 for a drill bit for it not to work or break. I just plan on driving the car to the shop only to get the studs fixed. I will not drive the car for any other reason until the studs are fixed. I have 2 machine shops that are 2 miles away from my house so I figure the drive wont be too bad without the 1 or 2 studs off.

Basically after contacting the machine shops in my area they are saying that I pretty much need to take off the head and take it to them to get the studs out. So I guess I am going to have to try out the carbide tip drill bit! I really don't want to take apart my perfectly good running car for these 2 dumb studs. Now I see that the carbide tipped drill bits are made to drill towards the left. (counter-clockwise) Do they make carbide tipped drill bits that drill towards the right?? (clockwise) If so where can I find them?
 
Best of luck on getting it out!

Just take your time and do not let this happen...

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Best of luck on getting it out!

Just take your time and do not let this happen...

You must be logged in to view this image or video.



Thanks a lot! WOW! Can we say trash can? LOL :applause:



Has anyone ever tried using a dremel with a very small grinding stone to grind down the stud or broken extractor? (Assuming they make grinding stones that small)
 
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I just finished drilling out & replacing 2 studs broken off below the surface about a month ago. The big one and the next one over on cylinder 4. Did it with the head in my car and used a cordless drill. It took me about 10 minutes to drill through what remained of the studs and finished everything in about 2 hours. Drilled straight thru without hitting any of the threads on the head & didn't need to remove the radiator for extra room. Pulled the heat shield & manifold, packed the port with a paper towel, drilled, extractor-ed out the broken studs, chased threads with a tap, anti-seize and installed new studs, re-assembled. BP Blastered thru the holes in the studs to help wash out and lub as I backed out the broken studs. Cleaning the MLS exhaust gasket took the longest. This is not really that hard with using the correct tools.
 
Good luck with the grinding stone. I tried porting my housing once with grinding stones... it doesn't work. You're better off going to your local napa and seeing if they have a small enough carbide porting bit to get in there. They're $10 at NAPA and would work much better than a stone.
 
Good luck with the grinding stone. I tried porting my housing once with grinding stones... it doesn't work. You're better off going to your local napa and seeing if they have a small enough carbide porting bit to get in there. They're $10 at NAPA and would work much better than a stone.

Carbide pointing stone! I'll definitely look into that! I am not gonna give up on this stud! I'll get it out sooner or later! :hellyeah:
 
Since it is a 8mm stud or about 5/16.

Keep the stone or carbide burr in the 1/8 to 1/4 size range.

Or you can just pull the head off, and send it to me, and Ill get it out on the work bench!! ROFL
 
Since it is a 8mm stud or about 5/16.

Keep the stone or carbide burr in the 1/8 to 1/4 size range.

Or you can just pull the head off, and send it to me, and Ill get it out on the work bench!! ROFL

Thanks for the help! I think it'd just be cheaper to get a bare head and swap all my parts back to it! Lol I just would hate to take it all apart when it's running great!
 
My friend had this same issue. It started out by having 2 broken studs on the exhaust manifold to him trying to drill holes. Then using Irwin extractors to get it out and now the head is off the car. To bad he couldn't listen to me telling him to take it off in the first place and bring it to a machine shop. Some people just don't know and others have to learn the hard way because they're hard headed. Either way good luck.
 
My friend had this same issue. It started out by having 2 broken studs on the exhaust manifold to him trying to drill holes. Then using Irwin extractors to get it out and now the head is off the car. To bad he couldn't listen to me telling him to take it off in the first place and bring it to a machine shop. Some people just don't know and others have to learn the hard way because they're hard headed. Either way good luck.

Thanks for the advice! I will get through the studs! It'll take some time but ill get it done!
 
Here are some up to date pics of the 2 studs!

Here is the first one with the broken extractor. See any progress? I started both with a 21/64 cobalt bit yesterday.



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Here's the other that I am drilling out to helicoil.


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You are drilling with too big of a bit. That is going to take you until next July to drill out using a bit that large and not carbide. Drill a pilot hole with a small carbide bit, so the larger bit has an edge to bite into. You are going to just have to get carbide. Cobalt bits just won't cut it, figuratively and literally. Get it with a left hand twist so if it catches when you are drilling, you aren't just forcing the broken stud down into the head even harder.
 
Yep. I do this for a living & tried to tell this back in post #11 and a couple other following posts as well. Carbide or don't waste your time. By now the faces and probably work hardened too meaning this is going to be even hard to do.
 
It is definently work hardened. It looks like it has been heated and peened. The only way to dig thru that is to start very small with left hand carbides and work up in size. Once enough of the center is cored out, the stud will likely flex enough in the threads to get an easy out in it and back it out without any trouble at all.
 
You are drilling with too big of a bit. That is going to take you until next July to drill out using a bit that large and not carbide. Drill a pilot hole with a small carbide bit, so the larger bit has an edge to bite into. You are going to just have to get carbide. Cobalt bits just won't cut it, figuratively and literally. Get it with a left hand twist so if it catches when you are drilling, you aren't just forcing the broken stud down into the head even harder.


I am going with a carbide bit! I am going to try a 3/16 for starters and see where I am when the dust settles.

Yep. I do this for a living & tried to tell this back in post #11 and a couple other following posts as well. Carbide or don't waste your time. By now the faces and probably work hardened too meaning this is going to be even hard to do.


Hopefully the carbide will bite into it!

It is definently work hardened. It looks like it has been heated and peened. The only way to dig thru that is to start very small with left hand carbides and work up in size. Once enough of the center is cored out, the stud will likely flex enough in the threads to get an easy out in it and back it out without any trouble at all.


I will be sure to let you guys know how the carbide bit does!
 
This isn't going to be as easy anymore because of the work hardening. You need to use a slow speed on the drill while drilling. Use a drill that you can adjust the rpms on so you don't run the drills to fast. Also keep the drill straight meaning make sure that your pushing pressure on the drill bite is dead on straight. It's when you get drill off axis that they break. This is called "surface feet per minute" & "speed & feed" and changes with different diameter drill bites (smaller-faster, bigger-slower) and material.
 
This isn't going to be as easy anymore because of the work hardening. You need to use a slow speed on the drill while drilling. Use a drill that you can adjust the rpms on so you don't run the drills to fast. Also keep the drill straight meaning make sure that your pushing pressure on the drill bite is dead on straight. It's when you get drill off axis that they break. This is called "surface feet per minute" & "speed & feed" and changes with different diameter drill bites (smaller-faster, bigger-slower) and material.

Thanks for the help! I just am trying to avoid taking the head off! Im sure ill eventually get it out with a lot more time and effort actually working on it!
 
3/32" would probably do better. The first pilot hole should be really small. A small bit will cut easier, but you have to be real careful to put just enough force on it to dig in and push dead in line with the bit. Run it slow with a little oil to cool it as you go.
 
Yes a little oil every few seconds. As soon as the oil smokes and burns off.
 
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