engine makes clicking noise when trying to start - valves not opening

[george8]

I have a Toro 22" recycler, bought in 2017, and have changed oil and uses stabilized fuel over the recent years. Engine is Briggs and Stratton 128M02-0017-F1.

I tried to start it up this spring, and the engine didn't turn over after a few pulls, and then all of a sudden it started making this clicking noise when I would pull on the starter cord. I opened it up to try to find if there is meatal on metal rubbing, and the flywheel on top and bIade on bottom moved freely. I took off the cylinder head and muffler to look at the valves and think I spotted the problem. Piston movies smoothly, but neither valve moves much when spinning the motor in the correct direction and I hear the clicking noise with every inch of a turn of the flywheel.

I reversed the spin of the flywheel, and the intake valve opens smoothly, but the exhaust valve does not open much and when it should finish it's cycle to close, there is a click and it moves about 1/10 inch. I'm not sure how to open up more of the engine to access the valves. Any suggestions before taking this in to get serviced? I uploaded a video on youtube of the clicking. Thanks!

 

[dougand3]

Camshaft lobes aren't bumping valves open....I'd guess camshaft gear or timing gear on crankshaft failure. Maybe a tooth broke off and doesn't engage CW but will catch CCW. Gotta split the engine (2-3 inches from the engine bottom, you'll see a thin gasket). Engine splits into upper cylinder and sump. See what parts are needed - camshaft, timing gear, maybe oil slinger/governor, gasket set. Probably over $100 in parts and that's you doing the labor. Shop fix will be real high $.
I had a similar case - Briggs 12S912 that blew up the oil slinger/gov. Damaged cam and timing gear. Parts prices too high to fix when I found a suitable Briggs mower with a dirty carb for $15.

 

[Fish]

I believe yours has one of those plastic cams, and the teeth are boogered up.

 

[george8]

It was a broken camshaft. Had to get it fixed and cost me 50% the price of a new one. Didn't have much of an option, but this was helpful to confirm that I wasn't missing something simple.