Monday, August 26, 2013

Briggs and Stratton 21HP Won't Crank Over

My Grandparents new lawnmower refused to start, it would crank part way over and the compression stroke would stop it. It was under warranty, so Sears sent a guy out, it wasn't the valve adjustment, starter, or anything simple, so he came back and put a new engine on it. We've got a broken cub cadet, also my grandparents, that had a Kohler Courage which cracked the engine case after 2-3 years! I told them not to buy another one of those! But the Briggs didn't survive 6 months! The repairman didn't need the old engine, so he didn't mind leaving it for me to try to fix.


  • 21HP Briggs and Stratton
  • MFG in 2012
  • 331877 - 2371 - G5


Here's the problem, the compression release weight has failed.

Camshaft and compression release weight
It's made of some sort of cast metal! The hole for the shaft is 1/2 the thickness of the actual weight! What are you thinking Briggs? At least machine it from mild steel, then it wouldn't snap!
Broken compression release weight
Well that's the problem, a new camshaft will cost ~$80, but if it has the same cast weight on it I don't know that I want it! I'm not sure how to proceed at this point. I could try grinding one out of steel, but that's going to be a job.

UPDATE: We decided to go ahead with the new camshaft. It's installed on the Cub Cadet and still working as of April 2015.