Removing a broken bolt (and replacing an exhaust manifold)

My down pipe on my exhaust broke open, so I tried to change it. After a 5-hour struggle, I emerged (kind of) victorious. One of the studs on the exhaust manifold broke off without warning (no resistance at all - it just broke). The next day, I bought a set of bolt-outs that drill into the stud. Once I got the bolt-out into the stud, I gave it a little twist and.... it broke off inside the bolt! My drill bits won't drill through the broken bolt-out, so I'm pretty frustrated. I've tried heat, cold, oils, hammers, vice grips, etc and this thing won't budge!

Anyway, what I wanted to know was: does anyone have a trick for removing that stud? If I don't get it out by next weekend, I'll probably end up getting a new manifold from the junkyard, but I've never changed one before. Are there any tricks to replacing one, or do I just slap the gasket on there and bolt it on? (I have the torque specs and the tightening order).

The engine is a 1.6L Nissan GA16DE with 118k miles.

you'll have to use a thing called a helicoil. if it's even possible to work with.

the drill-out thing is most likely made of HSS steel, and if so it can't be drilled out with anything less than a diamond drill or gundrill. carbide-tipped or whatever won't touch it.

you'd have to have it milled/drilled then threaded and insert a helicoil to make it the right size for a new stud.

many easy-outs and what not are made from tungstun. Nearly impossible to drill out.

Its tedious, but in such a situation, I have been known to use very tiny drill bits and drill a series of holes around the easy-out, then hit it with a chisel and work it out.

I can't remember the name of the process, but its kind of like a plasma cutter that bores holes in metal. Some machine shops have it (its a three letter acronym....RID?) and you could have the stud and extractor removed in this manner, and then rethread or helicoil the hole afterwords. Might be easier/less effort to just get another manifold though

You can also try the following. I've had success with it in the past.

If you have a rotary tool (aka a router), attach a heavy duty steel cutting disc to it. The make a groove in the bolt-out to make it look like a flat head screw. Then use a flat-head screw driver to torque it out. This would be easier if you posted a picture. You're lucky it didn't break off on your engine, because you can't manipulate an engine as easily as an exhaust manifold.

The process for removing a broken off stud is EDM, electrical discharge machining. Some machine shops have them but could charge you $60 and up per broken stud. A water jet cutter works too.

I like the idea of a slot ground into the leftover bolt, even if you have to grind into the manifold a bit as long as there is enough meat left as not to weaken it. Can you post a picture of what you have?

If there is a little bit sticking above the surface, file a couple of flats on it first. Then heat up that portion of the manifold with a propane torch, lock a pair of visegrip pliers on it and give it a go.

Bob

I'll take a picture when I work on it this weekend. Yes, there is a good chunk of it sticking down - enough to clamp some vice grips to, but they don't bite enough. I've been told that the stud is actually welded in place on my particular car.

As for the torch idea, I've already hit it with a torch and vice grips, but I didn't file any flats first. I'll have to give it a try. The screwdriver might work too, but I don't think I can get enough torque on a screwdriver.

Thank you guys for the advice.

The process for removing a broken off stud is EDM,
Beat me to it, also called "spark eroding".:)
The units are getting cheaper, many machine shops have them now.

You will probably not get enough depth to a slot for a screwdriver to work well. You'd need to make it tight, have someone push down on the screwdriver hard and turn the screwdriver with a pipe wrench. Hard to do with a loose manifold though.

I'd take it to an automotive machine shop or look for a replacement manifold unless you don't need the car and have time to burn. The stud being welded in place is not a good sign that it can be fixed easily.

Bob

I haveworked on 5-6 cars (not many), but from what I've seen, they've never welded bolts for the exhaust manifold. Under the intense heat of the manifold, the bolt and the manifold will fuse together partly and the bolt won't come out easily. So welding is completely useless. Why not well weld the manifold on instead?

there is no way slotting it and using a flat blade will work. The stud is siezed in there. All you'll do is break flat blades

that method only works when the bolt/stud isn't siezed

as for heating with a propane torch, doubt it'll do any good.

even for loosening the nuts on track rod ends we use an oxy-acetylene torch.

I'm going to pick up another manifold at the junkyard, but I'll still try to fix mine so I can sell it or return the other one to the yard. My friend just got his acetylene torch refilled, so we're going to try that while its off the car.

Worst case, I'll be out 40 bucks (+30 to ship the gaskets in time - nobody had them in stock around here).

Well, I might not get the damn gasket in time. I guess Fed-Ex may-or-may-not ship to my house on a Saturday. Can I reuse the old manifold gasket until the new one ships (assuming its not broken), or should I just wait until I get it?

wait for a new one, you shouldn't re-use gaskets.

I tried the acetalyne torch and got nowhere. I started drilling into it, but my friend needed to leave, so we put it back together. Its all quiet now, even though the stud is still broken off. I'm not going to ask questions :grinyes:

It can be done with the torch if you know how. THAT IS AS LONG AS THE MANIFOLD IS CAST-IRON.