How to remove a bolt from cast iron

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Posted · Report post

Anyone have any suggestions for removing a bolt from cast iron?

While working on a car, I sprayed the bolt with penetrating oil and the manifold bolt still sheared at the flange. The rest of the bolt and nut are still attached to the other side of the CI flange. I would like to remove the bolt leaving the threads in the flange, otherwise I need to get the bolt out and drill the threads out of the CI.

An internet search suggested all manner of petroleum penetrates, water, and heat followed by an application of wax to wick into the threads.

Before I started, I thought I would ask y'all what you suggested. Any ideas?

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Posted · Report post

While I haven't had this problem in CI, I've sheared some heads. My successes have been with 2 methods, heat and screw extractors. The heat has been more reliable. Sometime the screw extractors just bugger everything to the point of drilling and re-threading.

But I'm no machinists, someone with more experience my give you better advice.

Good luck.

ron

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Posted · Report post

I always use plusgas as a penetrating fluid it works the majority of the time but exhaust and head bolts and the like are prone to snapping if that happens now , if possible I weld a new nut on the broken bolt , high temp of weld usually does the trick .

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Posted · Report post

I you have access to it welding something on to the remaining bolt can work well. Usually a nut plug welded over the piece. If no access then drill and re tap may be your only option in which case be very carefull to keep the drill centered on the bolt. If your careful the threads will peel out that way. One thing I have not tried yet is to blow it out with oxy acet cutting torch, it will cut and remove the remaining steel but not touch the cast iron threads. If the remaining piece is rusted in then easy out will probably not work.
Good luck
Rob

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Posted · Report post

If this is the bolt that comes off the manifold, I have tried many methods. Sometimes the penetrant works, sometimes the "weld a nut on" works. Two times I have ground the bolt flush with the manifold (both sides)took a small tip in my cutting torch, heated the bolt shaft and blown the inside out. Then I cleaned it as best as I could and ran a tap thru it. It worked both times. If you think about it, You can cut steel but you can't cut cast. Worst case scenario at this point would be drill the cast and put a regular bolt in it.

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Posted · Report post

Hi Glenn,
As the nut is still attached to the bolt, is the piece definitely screwed in with the nut acting as a lock nut?

If it is, the parts should be seperable which may make it easier to work with, it seems unusual to have a bolt screwed into a flange which then requires a nut to secure the fitting to it


First I would consider welding the existing nut to the bolt, and this should give enough heat to unfreeze the bolt, failing this, apply some heat to the flange rather than the bolt, with a torch, and put on some penetrating fluid (whilst still hot)then try to undo using a good close fitting socket or ring spanner

If this fails, then I would consider resorting to drilling out the offending piece.

Does the piece have to be rethreaded? or would a bolt and lock nut suffice in this situation? In which case just redrill to the bolt size.

Whatever your choice or method, please keep us informed and good luck with it

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Posted · Report post

not sure if I totally understand but if you have access try center punching the broken stud and drilling it out using small drills to start and working up to tap drill size for that stud. then try re-tapping the rest out. at any rate do the least destructive method first and work your way up to thermonuclear devices.wink.gif

bob

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Posted · Report post

Glenn, you should've bought a Chevy!!!:D

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Posted · Report post

It is a Pontiac LOL

The bolt sheared at the head end of the bolt, and flush with the CI manifold branch flange. The bolt threads and a nut are on the other side on the flange. It is in the flange tight enough that I thought there were threads involved.

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Posted · Report post

Glen,
If it has a nut it usually won't have threads. You might try heating the corner of the manifold to red and try to turn the nut. If it's rusted in this will usually free them up
Hope this helps

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Posted · Report post

Ok, first things first, break out your camera.
Torching out a broken bolt or stud, don't use this trick on a blind hole.
ATF and naptha is just about as good as it gets for penitraints.
Are you dealing with a exaust stud? Comen on the dounstream side of a exaust manifold.

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Posted · Report post

Yes it is an exhaust bolt, one that holds the exhaust gasket in place.

This manifold has a Y section. The straight through goes through the muffler and out the back of the car. The branch is where the second gasket is located. Someone before we got the car, cut the pipe about 8 inches long, then crimped and welded the end closed. In trying to replace the donut gasket, both bolts sheared at the Y section manifold when we tried to take them out.

I am getting my options on the table now so we can fix the thing when the car and Whitesmith come in from college for Easter break.

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Posted · Report post

Beleive it or not, Jeff Seeyle has the answer. I have done this many times. As he points out, steel cuts well with a torch, cast iron doesn't cut well. Actualy one must be very carefull using this method, it is possible to damage the threads slightly, but generaly works very well. After blowing out most of the bolt, allow to cool thoroughly, remove slag with a drift punch, then chase with a tap.

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Posted · Report post

Glenn In my expierance heating exhaust hardware sometimes works if it does not thebolt become extremely hard and differcult to drill afterward I would heat as alast resort if you have room centre punch and drill to the largest size stud extractor thats possible, use the straight fluted stud extractor such thatr are used on pipe as the spiral ones will expand the soft steel into the threads, some times are called brass fitting extrators. If it indeed it is a bolt still drill and punch out. hopes this helps.

Regards Mark

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Posted · Report post

Ok Glenn, centerpunching and drilling is a pain, I would use this as a last resort. If their is a bit of the stud sticking out, try welding a nut on, if it's broken of flush, and it is not a blind hole try torching it out, last, center punch and drill ( if the bolt is broken of below the level of the casting, use a layout punch) then use an extractor. Eyeballing it and drilling it is hard as you have a uneven. The best advice is to remove the manifold so you can work on your bench. Trying to extract the broken stud wile laying on your back under the car is going to cause no end of heart burn. I recommend removing all 6 studs (assuming you have 2 manifolds) replace them with new studs and plenty of antiseise and brass nuts.

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Posted · Report post

Brass nuts are something that does make things easier, the second time around (grin)

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Posted · Report post

Hydrogen Peroxide works very well in this situation, sounds crazy I know, but it does work. Something else to keep in mind if you can get a good punch on it is the jarring from hitting it with a hammer will often help as well, I wouldnt be afraid to heat it, if you do and it doesnt work, and you later have to drill it out, then just weld a bit of 7018 rod right on it, this will take care of any hardening that may have happened while heating, you can drill threw the weld like butter, and it will mess up what ever surface hardening occured from the torch. I would dump a little hydrogen peroxide on it, let that set a bit then throw the heat to it myself. Sounds like its probaly not threaded and just rusted pretty solid,

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Posted · Report post

Brass nuts cost a few cents more (this is wy the manufacture dosnt use them) but are cheaper than fighting a broken stud. Even in phoenix where I grew up exast bolts, especially fine thread SAE and smaller diameter metric galled. If your car lives wear they salt the roads, it just exasperates the problem.
I highly recommend antieceise on exast and coolant system bolts, as well as weal lug nuts ( use a tork wrench, saves heart burn on the side of the road).
If you totally jack the treads up, no fear, heal-a-coil works, but I prefer the tread repair plugs, such as Boman carries, if you remember the "case savers" used on air cooled VW motors. They are plugs with OD and ID threads with locking pins on the out side (keeps them from backing out next time you galled the threads.

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Posted · Report post

I'll tell you something That we use at work alot.
Get a washer and weld the hole up while over the. Broken stud. Then weld a nut on to the washer. Using stainless rods. Then you can back it out.
The SS will hold up to using a impact. Usually.
Or drill it out with a smaller drill bit and then you can use a chisel to collapse the remainder inside the cast.
But the washer deal will work. You just Might not be able to get a impact on It. But we gotta do this pretty regular.

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Posted · Report post

(I feel dumb for asking but there are no dumb questions, right? :P) Are you SURE they are threaded and not pressed? Pressed should have a flange on the back side. Yes, I have done an exhaust with pressed manifold bolts, that is why I ask. I am pretty sure you are sure of what you are saying though.

If you have it all apart and time, throw it in a bucket of kerosene for a few days.

Phil

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