Annoying drone'ing/humming sounds around 55mph?

[Opeth]

This is beginning to become sort of annoying to me and only happens between 55-60mph or so when the truck has a constant light throttle and running at 1,500rpms in D. I believe the truck is shifting into 4th or OD when this occurs and is just running in really low rpms. I can shift into 3rd, and the sound goes away still running at the same speed/throttle but rpms are now up in the 2k range. I shift back into D, drops around 1800rpms with no noise but then drops down to around 1500rpms again and the drone comes back.

Is this something normal?

[irishboy02]

Sounds like an issue with your overdrive. How many miles do you have on your truck? Whens the last time you looked at your transfluid level? Might be a little low

[Opeth]

I flushed it completely a couple months back and still has proper level, truck has 56k miles.

[Trail X]

Based on the 55mph thing, I would have said a bearing... as bearing issues can sometimes have speeds where they are more evident.

However based upon what you said about it dropping from 1800 to 1500 and then droning... I'd agree that it could be your torque converter clutch.

However, it also seems strange that it doesn't do it in 3rd, because the TCC will also lock up in 3rd. Try driving in D3 for a while and see if the same drone occurs (might not be at 55 mph anymore).

[SteveTB03]

Do you have an exhaust? Because I have the same thing happening in my truck but its from my truck dropping into OD mixed in with the exhaust it drones.

My trannys new it only has 60K miles on it and everythings fine no fluid from the TC and all fluid is good with no shavings.

As long as it shifts fine and it isn't slipping id say its fine.

[Opeth]

It sounds like an exhaust drone because its coming from the passenger side rear. Exhaust is 100% factory, and its done it for quite some time now. All fluids have been changed so I'm at a loss. I do have an extended bumper to bumper warranty for 3 years still so if something does let go, won't be too big of a deal. I found a couple posts over on trailvoy of other members having the same issue with GM claiming it just is happening for no known circumstance.

[irishboy02]

with GM claiming it just is happening for no known circumstance.

HAHA- imagine that. Most other people would just laugh you off and say "comon, they know what they're talking about, you must just be missing something", but i wouldn't put it past them one bit.