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seized, broken bolt Boston

2K views 13 replies 9 participants last post by  bljones 
#1 ·
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?
 
#12 ·
+1

Me too, except that I used a helicoil kit afterwards ($40) and it worked perfectly and was successful. I would say to buy the very best titanium bits and work slowly from a small diameter up. Its easy.
 
#9 ·
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.

Down
 
#5 ·
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.
 
#6 ·
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.
 
#10 ·
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
 
#11 ·
In the 1970's I broke off a distributor bolt and the shop welded a nut on top of it and spun it out, just the way the porsche mechanic suggests. This is routine for a good machine shop or real mechanic, as opposed to some greasemonkey.

I wouldn't try acid, that will eat aluminum and concentrated nitric is sold for cleaning stainless--it generally doesn't care about acids. Also, tends to eat the folks working with it.

Assuming you have tried Kroil or PBlaster? A real corrosion buster, not just WD40? If not, try them first. Soak, vibrate, repeat, the damned stuff is NOT WD-40 it works.

And failing that or the machine shop, i'd suggest freezing them to break the corrosion. A slush of alcohol and chipped dry ice, packed around and allowed to thoroughly freeze the parts, then removed and allowed to come back to room temp (with a heat lamp or torch to make that faster, as long as you don't ruin the temper). Or a CO2 extinguisher, or bottle of CO2 from a gas shop. Two or three good hard freeze cycles will usually break anything free, no danger of detempering metal or starting fires, just some patience and care not to get frostbite from contact.

Loctite also makes a freeze spray in a can now, but I'm not sure how effective that would be compared to really brutal freezing on the parts.
 
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