On Mon, 12 Apr 2021 16:51:58 -0700 (PDT), TimR posted for all of us to
digest...


On Monday, April 12, 2021 at 7:16:56 PM UTC-4, wrote:
On Mon, 12 Apr 2021 08:06:10 -0700 (PDT), TimR
wrote:
While mowing the yard yesterday the lawnmower made a clanging noise and quit.

Pulling the starter cord seems too easy now and I hear it spin longer than it should. And no, it doesn't start.

Should I give up on IC engines and buy an electric? I've certainly had my struggles with gas engines the past couple of years.
Take the plug out. Stick a pencil in the plug hole and see if you can
feel the piston moving when you rock it over with the blade (wear a
glove). If you have one of those politically correct mowers with the
blade disconnect pull on the rope slowly. Just be careful you don't
get it wedged and break it off. (why I don't suggest a screwdriver)

If the piston is moving Bob is probably right about a stuck valve,
valve spring popped off or you blew a hole in the top of the piston.
My guess is you are buying a new mower.

Thanks. That's what i was looking for, help with a diagnosis. I don't know small engines at all.

So I pulled the plug. The piston is only about half an inch inside the hole, and it doesn't move. If I spin the blade, the piston doesn''t move, if I pull on the rope slowly the blades spin but the piston doesn't move.

I didn't think I hit something. there was a repeated metallic clanging noise before it quit, like something was hitting metal on every cycle, before it quit. But is there any chance there's a safety spline on the shaft that let go? Or is this one dead and gone?

The last time I had one apart was about 20 years ago. I loaned it to the neighbor kid, and he brought it back broken. I took it apart to see, and (I don't know the right terms) there was a yoke type attachment on the end of a rod on the piston, and it was broken in several pieces.

This part is called a connecting rod. I believe your new problem is the
connecting rod or crankshaft from your description.

--
Tekkie