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roper99 04-12-2013 07:54 AM

seized, broken bolt Boston
I have removed lots of broken bolts and screws from metal and wood but now have an impasse, and I will need machinist help. There are six M8 stainless bolts imbedded in a thin aluminum water jacket of a disassembled cylinder-case. Heat and strong force will ruin the case. A suggestion was to dissolve the bolt using nitric acid, I do not know about that process. A sailor friendly machine shop ( with an EDM machine ) not far from Bosston/Providence or in New England would be helpful info. Anyone?

downeast450 04-12-2013 08:13 AM

Re: seized, broken bolt Boston

I had a similar problem and managed to drill out enough of the center of the bolts to collapse them inward with a small punch then extract the hollow remnants. I started very carefully with a small diameter bit then continued to remove material from the center by increasing the drill size.

Good luck.


benesailor 04-12-2013 08:54 AM

Re: seized, broken bolt Boston
i have used the same exact process as downeast describes with great success

bljones 04-12-2013 09:24 AM

Re: seized, broken bolt Boston
center drilling and collapsing STAINLESS bolts without damaging the softer aluminum around it is going to be tough for a DIY job.

Some pics would be a big help-

roper99 04-12-2013 09:26 AM

Re: seized, broken bolt Boston
Drill out almost completely, then using a pick/scribe peel the bolt remains from the corro-thread area, is my fallback plan. Sharp aim of the center and luck might work out. The stainless seems extra tough, will not readily collapse, and the corrosion itself seems very hard. Acid is a mystery to me and seems far-fetched. Machine work might be too costly. I might drill, grind and pick at the remains.

sww914 04-12-2013 09:37 AM

Re: seized, broken bolt Boston
Take it to an auto shop with a MIG welder. Have them weld a 10mm nut on the end of the broken stud and immediately put an impact on it and spin it out. They should put the nut over the stud and weld through the hole. Fill it up. The weld won't stick to the aluminum but the heat will break the corrosion and allow the piece to come out. It might take a couple tries.
I was a Porsche mechanic. How many broken exhaust studs do you suppose that I've removed from aluminum and magnesium?
About $10,000.00 worth of profits over the years on this method, that's how many.

sww914 04-12-2013 09:40 AM

Re: seized, broken bolt Boston
BTW, I haven't used the drill and pick it out method for a long time and I don't own any Easy-Outs anymore. Don't need it and don't need them.

bljones 04-12-2013 09:45 AM

Re: seized, broken bolt Boston
SWW has the right idea.

Air-cooled Porsche and VW exhaust studs- I don't think I have ever RandR'd an exhaust or heater box without busting at least one stud. usually #1 cylinder.

downeast450 04-12-2013 10:31 AM

Re: seized, broken bolt Boston

Originally Posted by bljones (Post 1015601)
center drilling and collapsing STAINLESS bolts without damaging the softer aluminum around it is going to be tough for a DIY job.

Some pics would be a big help-

Sorry, I have no pics. It was a tedious process. I was removing ss machine screw stubs from my pedestal on the mooring with a hand held drill. I managed. Swearing at the dopes who don't understand "No Wake", helped. The ss I was dealing with may not have been as hard as the bolts you are removing. You should be able to jig up in a drill press. My "small punch" was an awl.


tommays 04-12-2013 10:42 AM

Re: seized, broken bolt Boston
I am often forced to do hand work on stuff that cant be carried to a machine

The value is such I would carry it to a machine (I have the machines ) if you can

On and Atomic 4 block for example the 18 head studs fail here and there and after cleaning up and using the still good studs and the head as a drill guide works well

You just need to buy a letter size drill that exactly fits the clearance in the cylinder head and use this drill to spot the hole so it is exactly centered

You can then drill through with the right size drill and the head will serve as a guide in keeping a hand drill true and a good taping guide

On really crazy stuff I can drill up a guide on the Bridgeport in a few minutes

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