Saturn making funny noises

2002 sc1 68k miles: when i drive down the road and it goes into 4th gear overdrive(automatic) holding at a steady speed in the 45 to 53 mph range, I get a faint hum,hum,hum, sound I

can hear as opposed to the steady “hum” of the engine. The car shifts

fine, smooth, the rpm on the tach does not change, stays steady (no

bounce around or go up and down on the tach ). Pop it into neutral and the sound goes away. No engine misfire, no exhaust leaks. Whats the deal? Any suggestions?

could it be fortelling of a bearing going bad someplace? anything to be

concerned about? I dont want to have to put a trans in this thing down the

road… changed the top engine mount already…



any input you have would be greatly appreciated.

briansc1