repair of bolt threads on block or weld repair

[Soundguy]

Cast should be ductile.. if it becomes brittle.. it's because it was welded on... improperly..

soundguy

 

[Harry c]

Most of the removal methods have been covered. There are a couple more that work.

One of my favorites: If the bolt is flush or above the surface, cut a screwdriver slot into the end of the broken bolt either with a saw or a thin cutting wheel on a grinder. Use an impact screwdriver, the kind you hit with a hammer, to turn the bolt out. You can actually cut into the surrounding metal without jamming the bolt.

Another method: Use a center punch and working at the edge of the bolt angle the punch and try to tap the bolt around.

Helicoils work fine. Make sure the coil is completely under the surface of the metal or it can be pulled out like stretching a spring. If you do a good job it'll break the bolts before it strips. I'm not a fan of the Keenserts.

 

[mpegg]

One more way to fix a bad or stripped hole, is to drill and tap it out 2 sizes large if there is enough meat there. Then get a good grade 8 bolt, put lock tight on it, preffer perminate, screw it in and cut it off flush. Then dill and tap for the correct size that you want in the center of the cut off bolt. We do this at my work all the time, and it has never failed, and we are a high production machine shop.

 

[R W]

Drill the broken studs as previously advised, then run a weld along one side of
the drilled hole, weld something suitable to the stud to enable you to screw it
out. I have found this method far more effective than any other that I have
tried.