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My Scotts 1642 tractor with a Kohler Command 16hp engine has started acting up again. When I turn the ignition it might try and crank but will only rotate about 3/4 turn at most. Sometimes it will try to turn, sometimes not. When it won't move at all I can sometimes "free" it up by pressing down on the top and try and rotate it manually a little but but even then the next time I try to crank it, only a partial rotation. The battery shows a full charge. What am I looking at and how do I go about fixing it. This has happened one time in the past and I got it working on a regular basis but that was forever ago and forgot what I did (if anything) to get it running. Any suggestions would be helpful. Thx, Wolf

Pull your spark plug and spin it with the starter to make sure there is nothing mechanically wrong with the internals, this will also test your starter / battery etc. This should isolate the problem and get you going in the right direction
If it ran low on oil - bad things can happen in the crankcase -

First thing I would be doing is removing the battery and have it load tested at your local auto parts store or auto shop. It it does not hold a load replace it. I recommend a battery with a minimum of 250 CCA for single cylinder engines and 325 CCA for two cylinder engines. If the problem continues with a good battery, I would be checking valve clearance.

Just changed the oil for the season a little over a week ago and the level is good. Battery was low so I put it on the charger. Tried to jump it off of the truck battery but it would still only do a partial turn. Put the charged battery on there and it turned a little before stopping but now I can't manipulate the top whatsoever! It's stuck tight! NOT a good sign to say the least. Siezed engine? If so, any options? Can't think the oil change would have had anything to do with this but the timing is suspicious to say the least. It was having the same problems last week but managed to get it started and it ran while we mowed our 1 acre lot. Granted it's a 20 year old machine so we've been very luck to have it last as long as it has but overall it's been taken care of and would like to squeeze a few more years out of it.

Did you jump the battery by connecting it in parallel with the units battery? If so you could still have a bad battery, as your good truck battery is losing its power to the units battery. Check battery voltage when trying to start the unit. If battery voltage is over 10.5 VDC then we know you have a good battery. If it drops below 10 VDC you have a bad battery. If you have a good battery, try removing the spark plugs and turning the engine over. If it spins freely, I would be checking the valve clearance.

Took the mower battery out and connected the jumper cables directly from the truck to the battery wires on the mower. You can tell the starter wants to do something but nothing moves that you see. Can't get any good leverage on the top of the motor like before to try and force it back counter-clockwise but will try to hook onto the shaft below the frame to see if I can somehow spin it and break it loose from below. Except for the motor, the rest of the mower is still in great condition for being around 23 years old. Tried to take good care of it and keep everything maintained. Where's the best place to get a replacement Kohler Command 16hp engine with vertical shaft if it comes to that?

I've seen this model come apart before - in my opinion they're poorly designed - ended up swapping out this type motor with a Kohler 20 hp, everything fit except the exhaust b/c it was a 2 cylinder - Small modification to the frame and it's a nice machine now. I'm betting something came loose in the crankcase and locked it up

Worked on the crankcase before when that L shaped piece was turned in the wrong direction and some little piece dropped into the pan. Wasn't a fun experience but got it back in place after tearing the thing apart. Not finding any engines that aren't an arm and a leg. Anyone know of any reliable and somewhat affordable suppliers for a new engine? Really would like to avoid laying out $2500-$3000 for a new mower right now as we will prob downsize in a couple of years to a place that handles all the outside maintenance.

Look on Facebook Market place , you'll find something reasonable

I may have to consider this my Easter miracle. Took the front belt guard off and managed to secure a rubber oil wrench strap around the belt pulley. Took several tries but finally managed to get enough leverage on the strap handle to break it free to where I could rotate the pulley both counter-clockwise and clockwise. Tried to crank it several times without luck and finally realized I had forgot to put the spark plug back in. Put the plug in and tried again and the battery just didn't have enough juice to start it even though it was fully charged during the first couple of cranks so it may still be something that needs replacement (3 years old). Still don't understand why it would seize the way it did and then appear to go to back to running normal. Thanks for your suggestions. Hope I can get a few more years out of this thing.

Low oil and in particular low oil running along a slope can deprive the top bush of oil so it runs dry for a couple of seconds then the aluminium rips out and welds to the steel crankshaft.
It is a common problem particularly on gravity fed engies as people mow carb side down which means it is pump side up
Usually we would pull the engine, remove the crankshaft degrease it then do a cold HCl dip or hot NAOH dip to chemically remove the aluminium then a polish with a scotch brite pad to clean up any remaining roughness ( NO ABRASIVES TO BE USED )
Then go up one grade thicker oil