Sheared flywheel key: the mower that hit a root and now backfires
Difficultymedium
Time45 minutes
Cost$2
Hit a rock or root, now it is hard to pull, backfires, or runs rough. The soft aluminum key between the crank and flywheel sheared to protect the crank and now the timing is off. Pull the blade, remove the flywheel nut (impact gun or a strap wrench), pull the flywheel with a puller (not by prying; you will crack the fins), replace the $2 key, torque the nut to spec (usually 55 to 65 ft-lb). Check the blade for bends while you are under there; a bent blade is a vibration that will shear the key again.
#flywheel-key#backfire#lawn-mower#repair#small-engine
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💬 9 comments
9 comments
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Can confirm, the cheap part is the one that fails. Replaced mine twice before reading this.
Should be the same procedure, the part moved slightly but the steps match.
Solid. Sending this to my brother who keeps asking me to fix his.
Should be the same procedure, the part moved slightly but the steps match.
This is the kind of post that makes this place worth it.
Yep, same here. The second time is always faster.
Followed along, got it done in about twice the time quoted, but it is done and it works.
Upvoted for the safety notes alone.
Bookmarking. I have exactly this problem and was about to pay someone.