Mowing MF 31 Sickle Mower with Smoking Gearbox. Any diagnostic tips?

[Coyote machine]

At a minimum you'll have to likely polish those crankshaft journals to get the surfaces cleaned up to a shiny smooth consistency across the bearing seating surface. This could be the reason you read excessive heat at the 'left' most bearing, (front of crankshaft?). Keep track of what is the upper half and the lower, (end cap) portion of the bearings for each journal so you can/could put them back in place if necessary. You might be able to have the crank checked for square by a machine shop to give you a better idea of the possible inherent issues with your rig, and as a point of reference as to where you're at overall in terms of what to do next- best approach likely hood of success prediction.
Let's see the bearings condition first......:thumbsup:

 

[Bid]

The local Agco dealer had a replacement bearing in stock. $19.83. The new bearing is sealed and is narrower than the original one. When the new bearing is used a spacer is required on each side to center the bearing. My mower did not have the spacers so I suspect when the previous owner replaced it the bearing was not center and it had some side loading causing it's demise.

 

[Sodo]

Those aren't really 'journals', they are simply bearing lands for a cartridge bearing. The spacers' main function would be to position (and maintain) the lube hole on the (narrow) bearing aligned with the zerk hole on the bearing cap. If the bearing cant get greased then that would cause the problem yer havin!

 

[Coyote machine]

I see that now they've replaced it with a sealed roller bearing with spacers to fill the void left from the original design/bearing used. Looks like it may work much better.
Please show pics of assembled crank with new bearings before closing it up.

 

[Bid]

The old bearing came off fairly easily. I touched up the crank with some emery cloth, put on the first set of spacers, the bearing, and then the other set of spacers. This was all real easy, but I struggled with the snap ring. It was a real pain!

I began prepping the housing to receive the crank when I discovered what may have been a major factor in the bearing failure. The connecting rod had a 1/16"-1/8" high x 1/4" long burr on the face that mates up with the bearing. The burr was on the outer edge of the face so I bet when the rod cap was bolted up it was putting a twist or point load on the bearing. I filed the burr off, reinstalled the crank assembly, bolted everything together, lubed it, and took it out for a test mow.

After an hour and a half of cutting without any signs of excess heat I was satified the new bearing and spacers took care of the problem. Next project: replace a few sections on the cutter bar.

Sorry Coyote, I didn't get any photos before putting the crank back in the housing. At that point I was so frustrated with that snap ring I just wanted to get the thing put back together.

Thanks everybody for your input and suggestions.