how do i repair a stripped bolt hole in aluminum after someone incorrectly installed a helicoil which failed .
oftentimes someone will use a drill size larger than specified or they may intermix threads such as standard or metric. ive never had a properly installed helicoil fail before in aluminum, cast iron, or steel. maybe if its really screwed up i could have a machinist make a sleeve with threads on the outside and threads on the inside to match my bolt , i could have the machinist drill, tap, and install this sleeve for me. i certainly dont want the person who screwed up the helicoil to touch the job again.
There is a larger OD insert that can be used if space allows. It is called a "keen-sert". It will allow you to keep your stock bolt size.
They are not available at your local hardware store but can be ordered as a single item from most industrial suppy, or do a search and order online.
I have also installed a heli-coil within a heli-coil (one at a time with red loctite on the outer insert).