going out next week to check on a motion 12 pulse unit. mechanic indicated that a howling noise was coming from the motor. he had the repair guys put new bearings in the motor, and no change, car runs fine, nothing hot, but a real loud hi pitched howling noise as car runs. they seem to think its drive related, have never heard of this, i could hear it in the background as i spoke to him, and it sounds really loud hi pitch howl or squeal . anyone had this before. repair guy is adamant that it is not the machine. sure sounds like the machine

I dont have any background on the machine, but sounds like something that I ran into not too long ago on an old westinghouse 38 with a flange mounted AC motor. The problem we had was that the motor sounded like the bearings were bad. it was not the case. I tore the motor down and replaced the bearings and even replaced the rear thrust bearings. did not solve the issue. finally I noticed that the taper lock on the coupling on the motor had worked the grub screws loose just a hair and had pushed the two couplings on motor and gearbox(the ones that have the neoprene like ring like a spider gear) together too tight. I pulled the motor, moved the taper lock and coupling back away from the gearbox about 1/8" and it fired right back up with no noise. The two were barely rubbing together metal on metal and not allowing the motor to find its balance causing a grinding or squealing noise. Might not be your problem, but its a suggestion.

It happen to me before also, the trust bearing went bad. Repair mechanic replace the trust bearing and the packing but pull the motor in too much and causing the high pitch noise.

thanks guys for the input i will check it out. sure sounds mechanical to me