Humming noise when 55+

[someday31]

2003 5.3 129,000miles......I get this kind of humming noise of sort when hitting 55mph+...It def not wheel hubs I know what they are like and I just did front Timkens a few thousand ago. Could it be driveshaft relate? Thoughts?

[j cAT]

Originally Posted by someday31

2003 5.3 129,000miles......I get this kind of humming noise of sort when hitting 55mph+...It def not wheel hubs I know what they are like and I just did front Timkens a few thousand ago. Could it be driveshaft relate? Thoughts?

check your tires. did this suddenly occur ?

over 55mph only I would guess a tire problem. bearings make noises at the lower speeds. check the wheel weights ...

[777stickman]

The easiest way to check if it's engine related or drive line related is to get above the speed when this happens and pop the tranny into neutral. Let the motor go to idle. It will only take a couple of seconds to determine engine or drive line.

[someday31]

Originally Posted by 777stickman

The easiest way to check if it's engine related or drive line related is to get above the speed when this happens and pop the tranny into neutral. Let the motor go to idle. It will only take a couple of seconds to determine engine or drive line.

I tried putting my truck in neutral while driving and the noise did not change/go away. Im sure it isnt wheel balancing because the sound seems to be from the middle of the truck...I noticed it seems to change tone depending on the ground, going up a slope or down a slope....Not sure what to do....

[j cAT]

Originally Posted by someday31

I tried putting my truck in neutral while driving and the noise did not change/go away. Im sure it isnt wheel balancing because the sound seems to be from the middle of the truck...I noticed it seems to change tone depending on the ground, going up a slope or down a slope....Not sure what to do....

If the tires are good not belt damaged, of the same wear , and properly balanced then the hum noise is most likely the rear diff., what diff oil is in there ? what color is it ? does it smell acidic strong ?

[someday31]

Originally Posted by j cAT

If the tires are good not belt damaged, of the same wear , and properly balanced then the hum noise is most likely the rear diff., what diff oil is in there ? what color is it ? does it smell acidic strong ?

I have lucas full synthethic in there, with the limited slip additive......I havent pulled the cover to look/smell....just changed it less than 15000 miles ago and it was fine then.... any way to check without pulling cover? How costly/complicated is that repair?

[4x4junkie]

you sure you need the limited slip additinve in your truck, this could casue a noisy rearend , and damage to the rear end if not needed. Also when was your tires last rotated, mine starts making noises from the tires whenever the tires have uneven wear..... rotating tires is important to keep noise from occuring.

[someday31]

Originally Posted by 4x4junkie

you sure you need the limited slip additinve in your truck, this could casue a noisy rearend , and damage to the rear end if not needed. Also when was your tires last rotated, mine starts making noises from the tires whenever the tires have uneven wear..... rotating tires is important to keep noise from occuring.

Before I did the fluid change I gave the dealer my vin and they said mine called for the additive. I havent done the rotation in about 8000 miles....I think I will start with that and do as J Cat said and check the balancing. Thanks for everyones insight!

[j cAT]

Originally Posted by someday31

Before I did the fluid change I gave the dealer my vin and they said mine called for the additive. I havent done the rotation in about 8000 miles....I think I will start with that and do as J Cat said and check the balancing. Thanks for everyones insight!

don't sound correct that you have in this vehicle a limited slip rear diff. also lets say you do somehow have one this means you do not use synthetic oil but GL5 80-90wt gear lube with 4 oz of the additive.this is the G86 diff in the glove box door...


with a 4wd truck that has 2wd select switch you will have an eaton locking diff. this is a G80 code in your glove box door.this uses 75-90wt synthetic oil. tag on the rear diff will tell you this !

replacing the rear diff oil means removal of the diff cover and cleaning out the debris.using paint thinner /mineral spirits and a cloth and brush to get all that goop out ..


lets say this had the wrong fluid installed and the diff was never cleaned ...good chance this is why you get drivetrain noises...could be the pinion bearing etc....

[j cAT]

you have a 4wd truck ! you have the eaton locker ................not a limited slip diff..........check those code numbers I gave and the tag on the diff...

[jdmccright]

Tires, especially off-road tires, can get louder as they wear down. I like to check out Tire Rack's surveys for any reports of increased noise as a particular tire wears.

But if it has gotten louder all of a sudden, then it could be the axle bearings, pinion, diff, u-joints, or even the center carrier bearing (for 2-piece drive shafts of extended/crew cabs). Jack the truck up onto stands and spin the drivetrain with the transmission in neutral.

Do any trailering or frequent hauling? Added stress can shorten the life of the diff oil, and as mentioned, if you have 4wd, you have a locking rear diff, not a limited slip. So no additive is needed, and for frequent haulers, it mey be recommended in the owner's manual to change to a heavier weight gear lube.

Finally, and completely different train of thought, you may have a loose piece of finish plastic underneath that vibrates in the wind at that speed.

Hope this helps!

[someday31]

Originally Posted by jdmccright

Tires, especially off-road tires, can get louder as they wear down. I like to check out Tire Rack's surveys for any reports of increased noise as a particular tire wears.

But if it has gotten louder all of a sudden, then it could be the axle bearings, pinion, diff, u-joints, or even the center carrier bearing (for 2-piece drive shafts of extended/crew cabs). Jack the truck up onto stands and spin the drivetrain with the transmission in neutral.

Do any trailering or frequent hauling? Added stress can shorten the life of the diff oil, and as mentioned, if you have 4wd, you have a locking rear diff, not a limited slip. So no additive is needed, and for frequent haulers, it mey be recommended in the owner's manual to change to a heavier weight gear lube.

Finally, and completely different train of thought, you may have a loose piece of finish plastic underneath that vibrates in the wind at that speed.

Hope this helps!

Brought my truck to one guy that does some work for me...he drove it and felt around the driveshaft and u joints....said its either a bearing in the transfer case thats bad or a u joint but wouldnt know till the driveshaft was out. Said there wasnt really any play in the driveshaft.....Im going to my friend that owns a tranny shop to see what he says about the transfer case.

[j cAT]

Originally Posted by someday31

Brought my truck to one guy that does some work for me...he drove it and felt around the driveshaft and u joints....said its either a bearing in the transfer case thats bad or a u joint but wouldnt know till the driveshaft was out. Said there wasnt really any play in the driveshaft.....Im going to my friend that owns a tranny shop to see what he says about the transfer case.

just run it till it gets worse before guessing on what it is...

make sure the fluids are correct and good..a bad U joint should be revealing its failure after a few hundred miles..a bearing will take longer..when a bearing gets bad enough you should see a leak or wetness.. at the drivetrain shafts input/output yokes.........

[GMCustomerService]

Originally Posted by someday31

2003 5.3 129,000miles......I get this kind of humming noise of sort when hitting 55mph+...It def not wheel hubs I know what they are like and I just did front Timkens a few thousand ago. Could it be driveshaft relate? Thoughts?

I would also recommend with starting with the tires. They can play a big role in the noise level of a vehicle. Flat Spots on tires can delvelop when tires which have sat and been cool for a period of time. Irregular wear on tire treads can also cause problems. Tires which have sat and been cool for a time will be stiffer and any irregular wear conditions will be more noticeable than they will be once the tires have warmed and softened. If you have further questions or concerns, please feel free to contact me. Thank you.

Tricia, GM Customer Service.