and the hits keep coming -- exhaust manifold

[DogBunny]

So, I'm looking at my passenger-side exhaust manifold studs after I removed the exhaust manifold. One of the studs has very bad threads, as in partially rusted away and disintegrated. I remember that as I removed the nut from that stud, that it was making a screeching noise with each turn. So, I decide to replace that stud.
With some work, I manage to get a nut on the stud -- I had to first dress the threads with a thread file before I could get the nut on. I put another nut on it so that I can double-nut the stud out. I wrote in another thread that the stud next to it came out when I was merely trying to remove the nut. Since that other stud came out when I was only trying to remove the nut, I figured that this stud would come out easily too.
I was very careful. The only thing I didn't do was apply heat -- because I don't know if applying spot heat is a good idea on the head, but mainly because the other stud came out so easily when I wasn't even trying to remove it.
As I said, I was being very careful. And the stud sheared off, level with the head surface.
Dang. The good news is that it is the second stud from the front, and with the upper control arm off, I will have a straight shot at drilling it. I am close to beginning a front end rebuild, so I will be taking the control arm off anyway. I have a really lot of experience with screw extractors, but in this case I'm thinking of going straight to a threaded-insert type repair kit, rather than risk having the screw extractor break off in what's left of the stud.
Any advice or comments are appreciated.
Bonus question: I took the exhaust manifold to the machine shop to be re-surfaced, and they said $60. I said wow, that's high. They said that on engines this old they are usually warped pretty bad and require more time to get flat. I said okay, but what do you think of $60?

 

[commando1]

ONLY $60.00? Just say Thank You to the guy!

I suck at getting out hardened steel fasteners. Especially a stud flush to the surface. If you do it, I want a step by step process for next time I do it.

 

[DogBunny]

$60 is good, for just one? Cool, thank you.
Regarding getting the stud out, I don't think I'm even going to try. I'm just going to drill it out and use a threaded insert. However, it might be a while. I still have an upper control arm to remove, and I'm moving very slowly on that.
I am about as un-expert on engines as it is possible to be, but I don't think those studs are hardened?

 

[saylor]

e z outs and heli coils... fun times.

id see if you can back that stud out before drilling it. chase the threads and boom you are back in biness.

 

[67Monaco]

Start your drilling with, a center punch obliviously, center drill. I find they walk A LOT less than normal drills. You won't drill the entire hole with it, but you'll get a good start.


But to be honest, I'd try every thing else to remove the stud before trying to drill with the head on the car.

 

[Ripinator]

I think you are wise to avoid using an extractor. Every time I ever used one, the damn thing broke off. I heard on another forum that a guy used a welder to build up the broken stud enough that he was able to clamp a pair of vise grips on it and back it out that way. Guy said it worked like a charm.

 

[bulldogchesty]

Can you weld a nut on it, and take it off with a wrench. Someone you know must have a welder. There is also a freeze off spray you might give a try.

 

[rexus31]

I had a stud break off; the first one on the driver's side. I was able to punch it dead center and drilled it out and used a heli coil. It's been fine almost 5 years later.

 

[DogBunny]

Thanks for all of the replies.
Here is my plan and why. I welcome all advice and dissension.
The stud remainder is recessed about an 1/8" in the block. The 1/8" of female stud-hole threads that I can see do not look good.
I figure that if I sheared the bolt when I tried double-nutting it out, then a welded-on nut would just shear off too. One of the reasons that welding on a nut works is because it gets everything really hot, expanding everything, if you work fast to get it out after the weld. But, that's why I don't want to do it, because I am afraid of the localized heat warping the block. Don't know if that is even possible, but that's my fear.
If you can get the whole object into an oven, so that everything heats evenly, then heat is great, and I wouldn't hesitate to use a screw extractor.
If it was a steel bolt in an aluminum head, the aluminum expands way more than the steel, and a long, slow heating from a heat gun would probably be enough to loosen it without warping anything, and again, I would use a screw extractor.
But, since it is what it is, I think the threaded insert is the best strategy. From the 1/8" of threads that I can see, I think the female threads in the block are probably crappy, and I will benefit from the insert. Yes, I will center-punch the stud, and I am good at keeping holes of this nature centered. My bolt supply place sells regular drill bits, reverse-twist bits, cobalt bits and Thunder bits:
http://www.carbideprocessors.com/triumph-twist-drill/twist-drills/screw-machine-thunderbit/
The idea of the reverse twist drills is that they grab the broken bolt and back it out. I have a full set, and I have never once had one of them grab and back a screw out for me.
The cobalt drills are extremely hard and good for drilling hardened steel and stainless.
In my case, I plan to use Thunder bits, starting small and working my way up. They should go through the stud fairly easily.
I do not have a 3/8-18 threaded insert kit, and am open to suggestions. The bolt supply place sells Recoil and Powercoil, both of which I think are better than Helicoil. I have never tried Time-Serts.
The original female threads in the block were probably an interference fit, so I'm not sure about that. Maybe I will be using a bolt instead of a stud and nut.
Also not sure if this particular stud has coolant behind it, but I assume it does. So when I install the threaded insert, do I worry about the insert itself being watertight? With that in mind, I plan on using PTFE (Teflon) containing paste sealant when I install the insert, and then again when I install the bolt.
BULLDOGCHESTY, I have always been skeptical of freezing. Never tried it, but it seems to me that it would just make everything contract even tighter.
rexus31, that is encouraging. Did you use a stud or a bolt?

 

[commando1]

On my recent heads fiasco on my NYB, I had to start with the smallest cobalt drill bits and work my way up 1/64th at a time until all the stud was drilled out.
I then drilled and tapped for a thread insert. I installed the insert with steel epoxy.
It worked perfectly.
Another day gone to hell on one little part.
Posted via Topify on Android

 

[bulldogchesty]

Good luck. How did you get your name?

 

[65sporty]

I remove alot of broken studs and bolts, with this one flush drill it, tap it if you can or helicoil it. the welded nut trick works if its not broken flush. you can use heat on the other studs without warping, I would never get any exh bolts out without a torch but I live in the rust belt. For the guys that like tools you can get 1/8 inch air powered die grinders and carbides. I have used this to remove broken studs and taps. hope this helps

 

[mr. fix it]

Okay, there are 2 ways to remove broken studs.

unless the threads in the head are stripped right out, you can use left handed drill bits after center punching the broken stud.

work your way up like Stan stated but stay under sided especially if the hole isnt centered.

What happens is the left handed bit acts to try to spin the stud out and the heat build up from the drilling process assists in breaking the rust free.
Works better than any easy out on the market

The alternative is to spot weld the broken stud unit enough of a nub is on the broken stud where you can get some vis grips on or weld another smaller nut or bolt onto the stud.

the welding process destroys any rust that is locking the stud into the head.
The heat expansion and contraction is what also destroys the hold on the stud.

there are a lot of videos on you tube showing the technique..

 

[DogBunny]

I installed the insert with steel epoxy.
It worked perfectly.

I like this strategy. This is what I intend to do.
My concern is that JB Weld is good up to 550 degrees, that's about as high as epoxies go. Exhaust manifolds can reach 1000 degrees. However, in this engine, the stud makes contact with the water jacket, so I'm hoping it doesn't get that hot. I think you did your repair on an other-than-exhaust manifold stud? Anyways, unless someone tells me to stop, or has a better idea, this is what I'm doing.

Another day gone to hell on one little part.

I hear that. How many days have we all wasted on one little part?

 

[DogBunny]

Thanks for all of the replies.

Good luck. How did you get your name?

My dog's name is Bunny. She is named after Sgt. Carter's girl friend from Gomer Pyle, USMC.

I remove alot of broken studs and bolts, with this one flush drill it, tap it if you can or helicoil it. the welded nut trick works if its not broken flush. you can use heat on the other studs without warping, I would never get any exh bolts out without a torch but I live in the rust belt. For the guys that like tools you can get 1/8 inch air powered die grinders and carbides. I have used this to remove broken studs and taps. hope this helps

I am going to Helicoil it. I think this is easy and most of all, safe. I know that heat is the way to remove stuck fasteners, but in this case, heat and welding scare me -- I worry about warping the block and making the situation worse. No worries with drilling and Helicoil. My only worry is that the original female threads in the block are probably an interference fit, and the Helicoil will not. Since it is part of the water jacket, I have concerns with leakage.

Okay, there are 2 ways to remove broken studs.

unless the threads in the head are stripped right out, you can use left handed drill bits after center punching the broken stud.

work your way up like Stan stated but stay under sided especially if the hole isnt centered.

What happens is the left handed bit acts to try to spin the stud out and the heat build up from the drilling process assists in breaking the rust free.
Works better than any easy out on the market

The alternative is to spot weld the broken stud unit enough of a nub is on the broken stud where you can get some vis grips on or weld another smaller nut or bolt onto the stud.

the welding process destroys any rust that is locking the stud into the head.
The heat expansion and contraction is what also destroys the hold on the stud.

there are a lot of videos on you tube showing the technique..

Thanks for the help. I have a complete set of reverse twist drills, but I have never, ever had one back out a stuck fastener. However, I will try them once again, once I get a nice-sized pilot hole using Thunder Bits.