Slight hum at 60mph

[mikeyss]

I do a lot of city driving so I don't get up past 45mph too often. The other day I was on the highway and noticed a slight hum coming from the rear at 60mph while hitting the gas pedal. It seems from 57-63mph the whine is there, when I let off the gas the whine stops, or it stops after 65mph. Also, this may or may not be part of the same thing, but on cold mornings when I back out of my parking spot and have the wheel turned, there is sort of a rotational creeking noise from the left rear area that goes away as soon as I straighten out. This is on my 09 Tahoe 4x4 with L9H and the G80 9.5 AXN axle. I have recently changed the diff fluid and I did put in the gm additive. Any ideas?

 

[Erickk120]

Did you have this problem before the oil change? What did the old fluid/ring gear teeth look like when you opened it?
When it comes to rear ends whining and it isn't the oil be prepared for future repairs. A common problem is a whine when decelerating which is what I was hoping for in your case but it isn't is caused when your pinion nut gets loose and it loses its preload.

• A “whirring” noise while decelerating at any or all speeds is most likely caused by bad pinion bearings or loose pinion bearing preload. This condition is typically always diagnosed as a bad ring and Pinion gear.

-"• A “howl or whine” during acceleration over a small or large speedrange is usually caused by worn ring and pinion gears or improper gear set up."-

• “Rumbling or whirring” at speeds over 20 mph can be caused by worn carrier bearings. The noise may change while cornering or turning.

• Regular “clunking” or loud “clicking” every few feet may indicate a broken ring or pinion gear tooth.

• “Banging, clicking or clunking” while cornering can be caused by broken cornering gears commonly called “spider gears”, lack of sufficient positraction lubrication, or worn positraction clutches.

• A “Rumble” while cornering or turning may indicate bad wheel bearings.

• A steady vibration that increases with the vehicle’s speed can be caused by worn u-joints or an out of balance driveshaft.

• “Clunking or clicking” when starting to move or getting on and off the gas might be loose yokes, bad u-joints or worn transfer case or transmission parts.

 

[Erickk120]

Forgot to add was it previously rebuilt at any point or is it the factory one. because if it was a rebuild before and it has that problem I would be sure it wasnt set properly.

 

[mikeyss]

I'm the second owner so I am not 100% sure what was done to it. I bought it with 130k and that's why I changed the fluid. We didn't pull the cover, just sucked the old fluid out and it actually looked fairly clean and not too stinky. I have only recently noticed the hum while accelerating at 57-63mph or so. I wish I got on the highway more often, maybe I would have heard it sooner. There are no vibrations that I have felt.

 

[Erickk120]

-"• A “howl or whine” during acceleration over a small or large speedrange is usually caused by worn ring and pinion gears or improper gear set up."-
I believe this is your problem, At least rear ends don't fail out of the blue, I will slowly get worse and worse if its a worn gear set, but with noise in the accel side I would remove the cover and inspect what the gears drive side look like, to look for possible abnormal wear, and maybe even look at the contact pattern. You said that there is no noise when coasting? Just when on the gas at 57-63ish.

 

[mikeyss]

Yeah, there is no noise while coasting. If it's wearing the gears, that gives me an excuse to swap out the 3.42 to 3.73, haha

 

[jmschin]

I have a 2019 Cadillac Escalade and I have similar issue as Mikeyss, I notice a slight hum or whine when driving at speeds from 57-63mph. When I let off the gas the hum or whine stops, or it stops after 63mph. A Cadillac dealer suggested the noise was coming from the differential. So I have replaced the front differential with a rebuilt differential but the noise is still there when on the gas at speeds from 57-63 mph.

Has anyone else with this problem found a fix for the noise ?

Any feedback is greatly appreciated.

 

[j91z28d1]

could be a few different things. from wheel bearings to driveshaft.

hard to say without hearing it.. usually I lean to drive shaft any time the sound comes and goes as mph changes, especially if it goes away or lessens again at higher mph. and changes when loaded and unloaded.

but it could also be many other things

 

[jmschin]

What is unique about the situation is the hum, howl, whine noise is only when accelerating from 57-63mph and when you let of the gas the noise immediately goes away.