I'm looking at the gap in the fracture.
If that gap is natural, and not enhanced for viewing,
It would suggest that the frame was stressed during
the welding process.
If you want to save the frame, you might consider
having a split sleeve welded over the fracture.
If the crack was purely due to the vibration and torque of the motor
that gap would be virually non-existent.
Personally i'd patch it. It's probably good for another 10-20k