motor cooling

We realize you can not change the electronics in the motors, however can you drill holes into the motor cases to release heat. It would not compromise the structure of case.
Would drilling holes to release heat be considered modifying the functionality of the motor, since you are cooling them off to not overheat and cut out?
Thanks

It’s not legal. Your question was already asked here:

Answered: Making holes to the motor’s case legal?

OK. Thank you kindly.