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I was mowing some tall grass and it bogged down the mower to the point where it died. I tried to restart it and it would not start. I hauled the mower into the shop to discover the flywheel would not turn. I tried to spin it by hand and it would not move. The mower is a Scott and is about 10-15 years old. I got it from my father in law. It sat outside for a number of years in the elements but i got it up and running a year ago and has been working well. Any ideas?

Any oil in there ?

Check oil level on dipstick, showing or not? Add if necessary, if ok remove spark plugs & try rotating top of screen by hand. Let us know what you find. Look at under side of engine pulleys, may have debris jammed between belts & pulleys.

Remove flywheel carefully with puller, replace flywheel key, key has been sheared. Flywheel keys are made of soft metal & are meant to shear under conditions you described, thus preventing internal engine damage.
https://www.google.com/webhp?source...UTF-8#q=flywheel puller for small gas engines change oil & filter after completing job & running engine for 10-15 minutes of warm-up. Post all numbers from engine data plate: model xxxxxx, type xxxx, trim xx & code 7 numbers.


https://www.youtube.com/watch?v=KkaD3h8J6es watch video

Ok. Checked oil level. It was low but still had oil. Maybe around 1 quart and was fairly dirty. No ubstructions under the mower. I pulled the spark plug and flywheel still won't turn. What I did notice was the flywheel did not line up with the flywheel key. I took a pick but do not know how to attach picks. Any ideas? Thoughts?

Basstracker94 said:

I was mowing some tall grass and it bogged down the mower to the point where it died. I tried to restart it and it would not start. I hauled the mower into the shop to discover the flywheel would not turn. I tried to spin it by hand and it would not move. The mower is a Scott and is about 10-15 years old. I got it from my father in law. It sat outside for a number of years in the elements but i got it up and running a year ago and has been working well. Any ideas?

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The underneath is plugged with a big wad of grass that has the blade locked in place.

Basstracker94 said:

Ok. Checked oil level. It was low but still had oil. Maybe around 1 quart and was fairly dirty. No ubstructions under the mower. I pulled the spark plug and flywheel still won't turn. What I did notice was the flywheel did not line up with the flywheel key. I took a pick but do not know how to attach picks. Any ideas? Thoughts?

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In any case, the flywheel is aligned by a key so the crank and flywheel rotate together. Perhaps the crank had stopped, but the flywheel's momentum allowed it to turn enough to shear the key. It sounds like you'll have to do some disassembly. Perhaps a piston is seized in the bore, preventing the crank from spinning. Perhaps the timing gear broke a tooth, or the timing gear key sheared, and caused the engine to be out of time, and there is interference. Maybe remove the head and inspect the pistons and valves and see if they kissed.

Connecting rod almost always seizes first. Cooling fins/shroud may be plugged causing over heating.

Walt Conner

A sheared flywheel key should only affect the timing. Go ahead and pull the flywheel and inspect it closely. It needs to be removed anyway.

Quick & dirty test is to get under the engine and grab the engine pulley.
You should be alble to move it up & down just far enought to ge an audiable click from the engine.This is normal & called end float.
If you can not move it up & down at all that indicates a seized crankshaft usually in the upper bearing.
If it moves up & down but does not click this usually indicates a siezed piston.
Both of these can lock an engine solid.
The other thing that can lock an engine solid is a broken magnet under the flywheel, so as the key is broken & you have to take it off, start with the flywheel.
If every thing is ok Under there then pull the engine , flip it over & remove the bottom 1/2 of the crankcase which should come off relatively easily as the crank will usually sieze to the upper 1/2 of the case and the piston to the inside of the bore or the con rod to the crankshaft.

update. I removed the flywheel and cleared out a lot of compacted grass around the pulley and now the engine rotates with my hands spinning the pulley. I do have a question and let me preference by saying I know just enough about lawn tractors to get into trouble. When spinning the engine shaft by hand at the pulley, I can get about 3 rotations of relatively smooth rotations and then it Boggs down pretty good for about 1/2 a turn and the frees up against and repeat. Is that normal? Is that a sign of further trouble? Again, thanks for all your help.

If you still have the spark plug in that 1/2 revolution would be the compression stroke, and will be quite difficult to turn by hand if everything is working properly. Removing the plug will make it easier to turn through that area. If the plug is out when doing this sounds like there could still be something hanging up.

One thing I though about is that i drained all the oil out of the engine. Would that make a difference in how easy it is to turn?

Not untill you start the engine.
'Actually oil add viscious drag at low speeds.
The only things to resist the rotation is the compressing of the vaalve springs and compression in the engine itself.
Pull off the rocker cover and watch the valves if the "hard" bits co-incide with a valve moving then what you are feeling is normal.