Craftsman YT3000 ride on mower

[bertsmobile1]

And check the depth of the hole in your crankshaft as your original bolt could have broken off inside the crankshaft
The hole should be the full length of the bolt + 6 threads length
The pulleys rarely bottom out on the crank shaft so you will need to slide the pulley on the shove some thing up the hole that is near the minor diameter of the original bolt then mark it with your third paw and compare that to the new bolt .
And a silly mistake is not to get the pulley in the key way properly

 

[Catchram12]

I tried with grade 5 bolt, still having trouble tightening it past 2 threads. It looks like the bolt is a size bigger but I am sure the size is as per recommendation. Please see the screen print.

 

[Rivets]

Have you tried running a tap in those threads to make sure they are clean?

 

[Catchram12]

Good morning everyone. I was able to get the bolt from my friend who had an old lawn mower that was not being used. When I compared that with the bolt I had, I see the threads on that was fine thread. That worked fine. Thanks Riverts for the suggestion on using roctite, I initially fixed without that and the bolt became loose after 10 mins of mowing but after applying threadlocker green and leaving it for 12 hours, the bolt stayed there there just fine.
Thanks everyone, especially Riverts and Startrec.
Are there any recommendations for typical maintenance of lawn mower? I change the oil, filters, sharpen blades, but this bolt getting loose was unique