Damaged Bolt Hole Repair Cheat Sheet

GTwildfire

In the course of preparing the V6 destined for the Fiero, I found it had three broken header bolts. Two of the holes ended up pretty messed up because the easy outs, and everything else I threw at the broken bits, did not work well. I had to make pretty large holes to get them clean enough for tapping, so I used the method described in the diagram below–install an oversized bolt and then make that the sleeve for the new correct-sized bolt that you tap and thread into its center. It worked beautifully, and if there’s ever a problem with these holes in the future, the resulting threaded sleeves can likely be removed pretty easily, and a replacement prepped using the same method.

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Posted at 11:39 am in How To, Ted Berner

Comments

GTwildfire
Jun 17, 2010 at 8:29 pm

The drill press was set to high speed at first, and I kept having to re-sharpen the bit. It took me a while to come around to the fact that the high speed was doing two bad things: 1. immediately evacuating the lubricant from the hole and shooing it away and 2. making the temperature go critical in about 2 seconds, especially when I was more than 1/4″ deep.
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Another really wild recent realization was that under some circumstances, when trying to drill some really tough alloys, a masonry bit can outperform one intended for metal, although I wouldn’t recommend using one for deep drilling.

TheMover
Jun 16, 2010 at 11:57 pm

About that tip to drill at lower r.p.m.’s to keep from burning the bit..I gotta remember that.

Bick66
Jun 16, 2010 at 12:15 pm

Great method! I’ll keep this is mind as I’m sure I’ll be faced with this kind of issue again.