You didn't say what type of motor. If an electric motor it could be the shaft bearing(s) are worn.
its the motor
the motor will continue to operate at a reduced speed and experience vibrations
replace it
Seafoam Motor Treatment.
Depends on why it is noisy.
Noisy operation of a motor is usually caused by the motor's bearings. Use an instrument that can check the temperature of the bearings. If they are hotter than the surrounding temperature of the motor's frame then change them out for new ones. New bearings should quiet the motor.
The name of the motor that can only operate on alternative current is called the AC motor. The AC motor consists of 2 basic parts with a rotor that is attached to the output shaft.
Good battery,slow cranking speed ,noisy,
They will be noisy and wear very fast.
electricity
The proper method to operate any given motor varies based on the specific model and application. The operation or owner's manual has detailed instructions on how to properly operate the motor.
They get noisy, squeal and vibrate. Also if you keep burning out the blower motor resistor, that is a sign the blower motor is on its way out.