Lawnmower Flywheel Key Replacement

The second time DD mowed No. 18 with No. 18's own mower, he forgot about a 2 inch steel pipe that must have been an old clothesline pole (I don't know why that would be in the front yard). He hit it with the blade and then the mower wouldn't start.

Symptoms: Won't start. Kicks back (back fires). Blows exhaust out of carburettor. Plug fowls with black oil.

Diagnosis: I was worried that the rings were compromised with all the oil on the plug. But I called the mower repair company which had put a sticker on the mower. The man told me it could be a bent shaft, or the flywheel key.

I searched the internet for some clues and found a video at http://www.small-engine-repairs.com/replace_lawn_mower_flywheel_key.html which explained the process. About this time DD came home and he did most of the work. Once we uncovered the flywheel we could see that the key had sheared and the wheel was turned 1/4 turn out of place. This makes the timing wrong which causes all the symptoms. We went to the mower parts shop and bought a new woodruff key for $2. Installed it, and the mower started right up. Then we returned the mower to No. 18 and dug down around the pipe and cut it off well below ground level. No more problem.