The Stovebolt Site Forums The Shop Area Engine Shop Broken Exhaust Manifold Bolt

I broke the bolt off (flush to inside). A buddy of mine says he has a snap-on kit for extracting them. Is there a tip on this site that goes over good options for doing this? I don't have a torch yet (other than a little propane one for plumbing), and engine is out of truck. Any advice or info?

Here are two Tech Tips that may be helpful:
http://www.stovebolt.com/techtips/bolt_broken_remove.html
http://www.stovebolt.com/techtips/bolt_removal.html

I like to TIG weld a blob on the end of broken bolts, then let it cool a minute to so, and vice grips on the blob to turn it out.
If it doesn't work the first time try again, nothing to lose or mess up.

I have a very nice set of broken bolt extractors, they work great when they work, but rusted and stuck stuff usually get the better of them. Great for broken pipe fittings and broken but not rusty stuff.

The advantage of welding onto a broken bolt is the heat is concentrated on the bolt, not the surrounding part. The hot bolt expands with the heat crushing and loosening any rust bond, then when it cools and shrinks the then somewhat powdered rust doesn't fight so hard.

If it takes you a while to get it to a welder it can't hurt to start soaking it with penetrating oil now. PB Blaster works well on the kind of rust found on exhaust manifolds/bolts.

Grigg

If you can't extract the bolt, you can drill it out. Use a drill bit that is just a size under the bolt size. Go straight, and if your lucky, sometimes the threads will spin out. If that doesn't work, drill out with bigger drill and tap or put in bolt and nut. Cecil.........

If it broke off because it's seized, it will need to be drilled (if Griggs technique doesn't work). I usually drill them as straight as possible until the little pieces of bolt fall out of the threads and chase the hole with a tap. If the threads are damaged I Heli-Coil it,
Scott

If it's really stuck, drill it out close but not all the way into the threads. Then try the welding trick, with no center it collapses easier and should come out.

Drilling is always my last option because it's difficult to get started on the center and keep it straight.
even when I do it on the milling machine it's tricky.
Most of the time welding is easier and faster than drilling without messing up the original threads.

Although it is satisfying to drill one out perfectly in the center and pull the single remaining thread out like a cork screw...

Grigg

Scott (or who ever want to answer),
what exactly do you mean by "heli-coil" it?

Helicoil is a last ditch repair after the threads have been destroyed and requires a “kit” consisting of an oversize drill, a special tap, the insert, and an install tool. Usually the most economical method is to give it to someone who has a machine shown in the link. Call a few machine shops and ask them where they send parts to have taps removed as I think at least one shop in every larger town has one.


http://www.electroarc.com/

Heli-coil is not (always) a last ditch repair. Frequently they are used to improve the strength of original threads particularly in aluminum.
Installed from day one in things like the tensioner bolt hole in many alternators..

Drilling to the next larger standard bolt size, or welding and re machining are last ditch efforts.
Don't be afraid to use a Heli-coil if the threads are not perfect, it makes for stronger than original threads and being stainless you are less likely to have a bolt stick later on.

Grigg

Thanks! Looks like I have some options. As soon as I get the bolts to get it on the engine stand I'm going to start soaking the PB Blaster on. Then (crossing all my fingers) maybe the snap-on extractor will work. By the way - what would be wrong with just using tap/die set to cut in new threads up one size if I screw the old ones up? Is that not a good idea?

... all I can say is you better have a GOOD, no make that GREAT set of taps. I have the same problem on a set of 283 ram horn headers.
First I got a nice center one of the bolts, drilled it out, put my GOOD "easy out" in it and when I had to crank down on it it popped like popcorn. So, drilled to the biggest I could without destroying the threads. I'm talking 32nd and 64th increments here! Still the old stuff would not turn loose....and yes, soaked them for a week.

So, today I tried the other header and all three of those twisted into as well. Soooo, I blasted them, cleaned them up real nice and tomorrow I'm taking them to a machine shop where they can put the TORCH to them. I figure they'll either come loose or we'll melt them out! I will rethread and use a helicoil if I have to. I'm tired of monkeying with them. These suckers are STUCK and no sense in me making things worse and causing more problems.

It may work, but not the best idea.
Often there is not room for the next size bolt, and you'd also have to drill the hole in the other part that it goes through larger as well.
If it comes to that the heli-coil is the best option, nothing is changed other than the (better) quality of the threads, still use the same size bolt.
If you really mess it up bad there are threaded inserts that go from one size down to the next smaller.

Try welding it first,
Or if you're set on trying the extractor be sure to drill in the very center. If you're off center you risk damaging the threads, and if the extractor doesn't work the of center hole makes any other method harder.

Grigg

Just don't use too much muscle with the extractor or a tap. If you break one of those off inside the siezed bolt, you'll need to have a machine shop remove them. That's why I head for the Heli-Coil route almost first thing. I've broken enough off too learn my lesson. Also, if the bolt is sticking off of the head some, be sure to grind it flat so it can be properly center puched before drilling,
Scott

center punch the broken bolt to be drilled that is always the best way to start drilling. the trick to drilling straight it to use a small socket that will fit snugly over the drill bit as a guide, keep your eye on it and make sure while your drilling that the socket base remains flush to the block. the best way to perfect drilling center and straight is to practice on a hard block of wood mounted in a bench vice using the center punch and socket