First let me say that this is a great site. It is incredibly helpful for a young guy that didn't live during these machines heyday. I have perused this forum for a couple of years and so far been able to find most of the information I needed by searching. I finally broke down and got satellite internet at the ranch so hopefully in the future I will be a more frequent poster. Anyway, my brother and I bought a D23j for our dad for father's day last year. It runs good and is in great shape. It had a bad precombustion chamber, so while we were in there we changed all four. When we were tightening down #2 it stripped out. One of the threads had a small gap in it, but we didn't think they were that rotten. Is this a common problem? The local small cat mechanic is a D2 fanatic and he said he has never seen them strip before. Should we just order the Helicoil cat precombustion kit or is their a better way to do it? I was not planning to remove the head unless I absolutely have to. Any help would be appreciated.

This is becoming more of a problem as these machines get older........but it is more common to have them strip out the threads on removal. The helicoil is still the best solution that I know of. Be sure to apply liberal quantity of antiseeze to the threads when installing along with new washers.

helicoil makes two kits; one standard helicoil kit and one cat kit that instead of a drill it has tapered reamer, but is twice as expensive. to find it you have to go to helicoil's website and look under special applications; it does not come up on a google search. has any

This is the setup I was referring to. The reamer approach may save having to use some alignment tooling. Cat used to provide this service. Did you try them??
Thread is a bit of an oddball (naturally) at 1 in.-12tpi.