Greetings!

I have a Tecumseh LEV 100, manufactured in 1998. The camshaft sheared off about 1/2" from the intake lobe. I wonder what caused this- if there was some stress on the metal or if the metal just gets old and weak. There was plenty of new oil, RPMS were right, valve was not stuck; it just sheared off when running normally.
Thanks for any help.

Probably just a bad casting on the crankshaft. Most likely nothing you could have done to prevent it from happening.

that one of those plastic camshafts?

if so, isn't it reason enough? :)