snapped bolts where elbow attaches to exhaust manifold

Very basic question, from a guy just getting started...

Just inherited this tractor (1959 Case 510B). My first project is to replace the muffler. Currently, there is no muffler, nor elbow. I can order both. (Elbow is about $45, while manifold is around $150) Both bolts (for attaching the elbow to manifold) are snapped off flush. Previous owner snapped off one, I did the other. I am wondering what is best to do next. I"m an experienced woodworker, so I can drill a straight hole, and I"ve done a little metal-working, but I have minimal mechanical experience. I spent a week trying to coax the bolt out, using PB Blaster, and the stud left inside is there to stay, completely seized. I thought I would attempt to drill out oversize and tap (either moving up a bolt size or using a helicoil. I"ve never done this before, but my other option is to remove the exhaust manifold from the head, and, if I mess that up, then I might have a bolt sheared off in the head, rather than just a bolt sheared off in the manifold. Those bolts look pretty rusty too, but the nuts are brass or something, so maybe easier?

Advice please?

Does this sound like a reasonable course? Is drilling/tapping cast iron doable? I understand that the procedure would be to attempt to drill centered and straight, so center-punch, drill pilot, and then drill progressively larger holes. I would be doing this with a hand drill, but the access is easy, so I think I have that in my favor.

I realize this is a pretty basic question, but it"s where I am, I guess.

Thanks,
Colin

If you got a welder weld a nut on to the broken bolts.

Yes, it"s doable. First of all, it"s important to drill on center. Center punch and drill a pilot hole. Then drill with the right size tap drill and retap the hole.

Welding when the bolts are flush can be tricky.

The bits don't always drill down the middle despite how well you mark it. If you CAN drill it down the middle you will need a good tap to clean out the threads.

I had a Dodge pickup with an off center hole drilled in the bolt and the easy out snapped off. What I did that time was drill a series of small holes around the easy out to release it. It honey combed the bolt and with some tinkering I got the bolt out.

You need that manifold in a vertical mill where if the hole is off you can correct it.

My 2 cents
RT

Thanks for the replies. I think what I will do is see if the manifold will come off easily. If it does, I'll see if I can get my neighbor to drill it on his mill.

This does raise another question, though. I see lots of advice on the net about heating bolts with a torch and welding. I have a torch and an MIG welder, but I would be very nervous getting either of them that close to the gas tank, and the (somewhat leaky) carburetor. Once again, I have minimal experience with the torch, and none yet with the MIG welder. Everything I worked on with the torch was in a blacksmith shop, so I don't know what people do in automotive shops. Is heating bolts or welding on the vehicle standard practice?

Removing the manifold and taking it to your neighbor with the mill is a good move. If the nuts on the manifold are brass. Then they will probably come off fairly easy. Too bad you can't put the torch on the nuts to heat them up, and let them cool, and use penerating oil This helps alot, but I can see your concearn about not wanting to burn down your tractor. You might want to remove the gas tank I know this is a pain in the fanny, but most tractors need that done just to adjust the valves. Your call. Stan

Colin,

Take it to your neighbor and do the

drilling with an end mill, that way you have

control of where the hole is .Those are 3/8

bolts , use a 5/16 end mill and with careful

centering it will take out everything but the

threads and they will come out like a helicoil.

Have removed more than i care to remember.

george

I'm surprised noone mentioned using left handed bits. I've drilled out lots of bolts with a cordless drill and lefthanded bits on a center punched stub. Even if you aren't perfectly centered once you get it so far a lot of times it will come out. You can also use a small chisel to coax it to turn once it's drilled most of the way. I've drilled and retapped lots of holes this way. Never had one not work out. Just be careful and take your time.

There's NOT a chance of a snowball in hell those bolts will unscrew with an LH drill bit they way they rust in place in those manifolds!

Smokewrench or careful drilling/milling out are the only way they'll ever vacate the premises!

I'm with Sidekick left handed bits are a top tool in this sort of job. Get the proper sized exractor. not an Easy Out! then get the left handed drill bit for it. You will enjoy it!

Manifold came right off, no problem. Dropped it off at a machine shop down the road (neighbor not home). The guy at the shop said he would tig weld a nut on and should be able to back out the studs.