JB Weld will NOT fix a spark plug hole: Here is how I know.

TLDR: Although many argue that JB weld can hold a spark plug in, as I expected, JB weld can not withstand the compression pressures of an outboard motor.


My 1970 Lark Evinrude 40....apparently had the top spark plug hole stripped by a previous owner. How do I know this?
Well Sunday afternoon, I attempted to replace the spark plugs...
Pull lower plug....looks like crap.
Go to parts store, and buy two new plugs...that was its own ordeal...but before I get off course...
Go home replace lower plug, all good. Pull top plug, go to replace and what,,, huh... this makes no sense. New plug, well it doesn't fit! I must aq....nevermind....

Hmmm...old top plug has a thread repair (steel) insert on it, and is stuck severely to the plug. The head itself looks terrible the threads that had been cut to hold the insert were terrible and not all there.
I got out the spark plug hole repair kit out....and started to tap and try to seat an insert in the repair hole.
Well the previous repair was at such an angle and so damaged that I could not get an insert to fit, the hole was too oblonged and damaged.

I figured before ordering a head (cheap on Ebay), I would JB Weld all the old threads (old repair) try to tap and hopefully get enough bite to seat an insert.

Well today I got an insert to sort of seat, but much like the V8 fords of the late 90s and 2000s the motor spat that plug and JB weld about 100 yards into the woods after about 26 seconds of running....
Good times

 

I was driving my 1995 Nissan 240SX from LA to Sacramento and half way there I blew out a plug. It had cross threaded and I thought it I had it in good but I guess not. I got off the freeway and there was a Pep Boys right there. I re-threaded it right there in the parking lot and hoped I didn't get too many aluminum bits in the cylinder. I then JB welded the insert in and waited about 10 minutes. I never had a problem with that engine again.