[Farmall] 100 breaking crankshafts

[John Hall]

Dad got a call from a guy that has a Farmall 100 that likes to break 
crankshafts. 3 of them thsu far. All running at low RPM when it 
happened--tractor is never used for heavy pulling. All broke beside #1 
journal. The guy said the last one lasted 3 years. Our thinking is either #1 
rod is twisted somehow or where the front main is, there is something 
causing the block to move---cracked block, something funny with a timing 
gear putting unusual pressure on that end of the crank. The tractor is too 
old too say the mains weren't line bored correctly at the factory. The guy 
asked is he possibly damaging the crankshaft when he drives the front pulley 
on. Never heard of ithappening myself.

What's your thoughts?

John Hall