Cracked spark plug

[Scrubcadet10]

Did a tune up on cub today, noticed when I took the plug boot off, the plug had a crack in the porcelain, or whatever it's called. What might cause it?
Poor material? I never go gorilla tightening them, just snug.

 

[Darryl G]

* post deleted*

 

[7394]

Ya know not tightening spark plugs to spec, can cause the plugs to keep the heat & not transfer it to the head as fast.

Just sayin...

I don't think it was expansion & contraction. They are made to handle heat cycles.

 

[Scrubcadet10]

I think the spec is either 18 or 22 ft lbs.

 

[7394]

If you go to 15 ft lbs that would be safe.. Or wind them all the way in "by hand" then put the ratchet & socket on & give a good snug.