I have removed a few engine bolts that broke when removing. The one I'm trying to get out of the 50 year old exhaust manifold won't yield. It is a 3/8" threaded bolt that threads into the exhaust manifold outlet/flange. It broke flush with the flange. Tried wicking it out with paraffin wax, soaking two days with WD40, heated with torch. Decided to use a bolt extractor. Drilled to use a #2 straight extractor.. and no movement. Drilled for a #3 spiral extractor and no go. Drilled a hole for a #4 spiral extractor no go. Then, drilled a hole with a 17/64" bit and the #5 extractor dug into the exhaust manifold hole threads. At this point, the threads are just barely apparent in the hole. At my wits end. Any suggestions will be greatly appreciated.
drill to suit 3/8 tap and re tap. If the hole is blind you may need to tap in stages with start intermediate and plug tap. this is based on your original holes drill were in the middle or very close.
sometimes if they are really stubborn I just drill the whole damn thing out and put a heli-coil in. saves a lot of time monkeying around and you end up with stainless threads, a lot less likely to freeze up again especially with a dab of antiseize going back together
I would say find a established muffler shop with the old guy in the back who knows how to use a cutting torch and have him burn it out , the bolt will burn but not the cast iron . the shop I deal with they have that guy and he always does the burn work and I never had a fubared manifold yet , the old bolt is turned to slag and easily knocked out with a punch and then I clean tap it for small ones he uses the oxy/ace torch and then turns the gas off and cranks up the oxygen when the bolt gets melted and then burns it as the tip is finer and puts a hole right thru the dead bolt and leaves all the threads .
If the hole is drilled out that far you should be able to remove the remainder of the bolt with a hammer and a small punch. Start at the top edge, catch the edge of the thread, and slowly tap it out of the manifold.
Stimp, I have a Victor Jr. cutting torch with oxy/acty. My old college welding book indicates grey cast iron melts at 2060 degrees and high carbon steel melts at 1425 degrees. so, there is about 675 degrees margin for error. If there is such a thing as melting cones I could practice on them. The old guy in the back sounds like a safer bet. LOL
The hole drilled is about 1/32" off center and is a blind hole. Heli-coil sounds like the best option. Thanks
Cerb they do make a real fine tip so you can concentrate the heat on the bolt and get it to puddle first . when it puddles then you blast it , the cast iron will wick the heat away fast enough to prevent it from melting and the steel will burn , but like I said find the old guy , if your not up to it .. ( mine charges me 6 pack money , and he no longer drinks swill beer so its $10) otherwise get a set of left handed cobalt bits and try that but if you have a hole in it get a small carbide burr and try to slot the bolt to the threads on one side to release the tension then apply some heat and wax then try to walk it out with a punch .
For the next time. Heat the bolt red hot and cool it with air. Do that about 4 times and it will come out easy. Do it about 7 times and you can take it out with your fingers. Welding a nut onto the stub works quite well. But it usually takes 3-4 tries. Somehow that's about the same heat cycles as it is with a torch. Even if the Stud broke way deep, you can still weld it.
If the stud is flush or below the surface, weld a washer thru the hole onto the stud and then a nut to the washer. Problem that people have with this method is that they are too quick to try and spin the stud out---let it cool a little bit first
Thanks everyone! I appreciate the wisdom and experience members share with other members in need of advice.
x3 on that. In my opinion bolt extractors are mostly useless. if the bolt broke, chances are a smaller more brittle extractor will break too. Then you have hardened steel to deal with. My favorite is to use a small carbide burr in my die grinder to make an off center hole. bring it out to the threads, then use a custom ground chisel point to collapse the broken bolt. Works like a charm once you get the hang of it. of course. It's much easier on the bench than working over the fender.
I went to Heli-coil's site and the 304 stainless steel heli-coil is good up to 800 degrees. On a non-turbo engine the exhaust manifold operating temperature range is 500- 900 degrees. Too close for comfort. I tried using a small chisel and collapsed the bolt in and tried to unscrew the threaded stud to no avail. Today, I will try 31 Vicky-s technique and heat the stud seven times or more. I'm at two attempts as of yesterday.
If over heating the helicoil is an issue then I would lay a heavy washer over the broken stud, use the mig welder to weld the stud to the washer then weld a nut to the washer, all that heat will break the rust bond and the the nut will give you something to put a wrench on
When I worked in a muffler shop I used to blow broken studs out with a torch all the time. There is a knack to it, you have to get it the exact right temp and hold the torch straight, and stand back from the shower of sparks. But when you get it right you can blow out the stud and not damage the threads in the manifold. As others said, one of the old guys at the muffler shop can do this in 2 minutes.
Oxy- acetylene I'm a welding instructor , so please excuse if I'm not too familiar with this particular situation but.. I do understand how a oxy- acetylene torch works. The acetylene is basically used to pre-heat the steel to near melting. That sets it up for the oxygen take over. The oxygen oxidizes the steel forming iron oxide( slag) this reaction is so violent it generates its own heat sustaining the reaction. How does this pertain to cutting off a bolt or nut leaving the mating surface untouched? The reaction won't jump a barrier. As long as the pre- heat is on one surface it will stay within that solid. Try cutting a nut off a bolt as a test and you'll see the torch won't cut the threads on the bolt. FYI
Is it a "blind" hole, or a through hole? I think I understood that one "side" of the hole is showing threads. I think I'd soak it a bit more with PB Blaster, etc, and try a straight square EZ-out driven in gently to span the exposed threads. The next day I'd gently twist the EZ out back and forth 50 times to see if I could get things moving. I would not hesitate to repair the thread with a helicoil, but getting the 3/8" tap drill centered over the original hole and not following the offset hole will be a trick. I think I saw an ad in a car or bike magazine for a drill fixture with hardened steel drill bushings for jobs just like this. Or maybe I dreamed it.
John Gizzi, Thank you for the lucid explanation of cutting a nut off a bolt. I have done this several times especially with rusted bolts(1/2" - 5/8"). Very strange phenomenon. Always was in wonderment as to why the threads of the mating bolt were not blasted away when the oxygen is introduced. Now I know the "barrier theory". Hmmm. I'm up to the challenge but dare to apply this phenomenon to the remains of a hollowed out steel stud fused inside a cast iron manifold blind threaded hole. The stud ends about 1/4" from the bottom of the threaded blind hole. The manifold is somewhat rare and a couple hundred bucks to replace. This evening, I heated the hollowed out stud with a propane torch until it glowed red a little bit, let it cool down, did this seven times. Then, filled the hole with 50/50 ATF and acetone, and left it to soak/penetrate over night.
I would Not try a torch in a blind hole! Besides the potential to heat both part's it will spit slag everywhere and will leave deposits behind.
Heat the bolt with oxy -acetylene. Use a welding tip to pin point the heat. Map gas will heat the entire area before the bolt gets red hot. Cool the red hot bolt with compressed air to shrink the bolt - A soaking heat wash from map gas and slow cooling probably won't do it.
If it's a through hole Drill a small hole through the bolt and use a torch to blow the bolt out. The cast iron of the manifold does not cut with a torch. Yes you can melt cast with a torch and blow the melted material out but it will not cut.
Lots of good suggestions here. Only thing I can add is toss the can of WD-40 (junk) and get a can of PB Blaster. Its amazing how much better that stuff works than any other penetrant I've tried.
The exhaust manifolds are cast iron free-flow exhaust manifolds. The block is a 390, forged crank and forged rods.
One thing I keep around is an old can of heat valve lubricant. Ford and AMC had it in spray cans. I has some graphite in it and will soak its way thru rusted areas real well. It was discontinued quite some time ago but I find it at swap meets on occasion.
Try a good rust buster and leave it a while. WD40 never works for me in past. Then the heat ,has worked for me many times. Don't just put wrench and be impatient
Mount your manifold with the good holes ,make a sleeve that fits the clearance hole with a 5/16 hole thru then drill the bolt out in most cases the threads will come out with bolt chips if not then run a tap thru just be careful and don't break the tap please leave the easyouts in the toolbox as they will only get you in trouble good luck
Ive used lefthanded drill bit and with whsts left in there it might just fall out. Also used an extractor set up that uses a left handed bit and the a corkscrew looking piece belind the drill that taps itself lefthanded and digs into the bolt. I think craftsman sells them. But you always got the helicoil to fall back on. yruhot
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