torque converter problem?

[LS1CHEYENNE]

Maybe you guys can give me some idea on this sound - I'll do my best to describe it . In the morning mostly when the truck is cold and I'm sitting at a light in gear with my foot on the brake there is this low fairly loud vibrating hum , kind of like the noise your brakes make when you're stepping on them but rolling slightly . Does this sound familiar ? If I put the truck in neutral it stops . It also seems to not do this when it's warmed up but this evening it seemed to do some even then . Could this be a torque converter issue or something else ? I haven't yet gone out and pulled the cover down but I guess it's time to do so . Could the bolts have loosened up and if so is there any way to tell without trying to torque them ? I haven't dropped just a tranny in a while . But the truck seems to run and drive just fine - no vibrations or anything . Thanks

[RedHeartbeat]

Check anything that revolves that can be loose. I'd start with the fan belt tensioner bearings, PS and water pump, and alternator. Check that the crank pulley is tight. Next move to the transmission bell housing bolts, drop the starter and make sure the convertor bolts are tight. Next check your driveshaft ujoints to see if they are in good condition. If you have a two piece driveshaft, check the saddle bearing rubber to see that its in good condition. Last, check that the pinion nut has not loosened up on the third member.