Loud pulsating humming

3474 Views 10 Replies 5 Participants Last post by Tbone Shuffle, Mar 3, 2022

Tarcher30

Discussion Starter · Feb 27, 2022

pulsating humming while driving
Good morning,
I have a 2011 Chevy Silverado four-wheel drive 5.3 flex fuel. 126,000 MI. Have this loud humming almost pulsating humming coming from the front end. It's very loud at slower speeds. It sounds like tire noise or etc. Just had a bunch of work done to it this noise was there before the work was done. Also Replaced both front hub assembly Replace the differential fluid in front and back. Transmission level is good and looks very clean. My mechanic has replaced oil cooler lines motor mount oil pressure sensor inner and outer tie rods and ball joints just recently. New tires not even 500 miles on them. I also put in new power stop brakes with the slotted rotors. They said that CV axles look good no visual cracks seem to turn just fine no clicking no popping. Took it to the differential guy who put some ears on it he also could not find any issue. Any ideas would be helpful I'm tired of throwing money at

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Chevy-SS

· #2 · Feb 27, 2022

I once owned a Pontiac Bonneville SSEi (supercharged 3.8L V-6). It was an awesome car, very fast and smooth, with all the bells and whistles. I maintained it immaculately.

At one point, it started making some 'mechanical' noises while driving. I swore it had to be a wheel bearing or hub. I checked and re-checked them all many times. The tires looked just fine, so I never gave them a second thought. I convinced myself it must be the transmission or diff, or something mechanical, but everything seemed OK.

About a year later (with noise still present), I put on four new tires. IMMEDIATELY upon driving away from tire shop, I noticed that the noise was ALL GONE!

I'm not saying with 100% certainty that your noise is caused by tires, but there's a damned good chance, especially since you've addressed most of the other causes.

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RedSLEd

· #3 · Feb 27, 2022

Maybe try to determine if the noise is rpm related or mph related.

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Tbone Shuffle

· #4 · Feb 27, 2022

Is the frequency of the hum lining up with the rotation speed of the tires? Tap your brakes while listening to the noise and see if it changes/goes away. If it does it could be brake related. Sometimes new brakes make noise for a while especially drilled and slotted and sometimes built up grim on the calipers doesn't allow the pads to move smoothly. I've had to clean the sliding areas on calipers before to get rid of brake noise. Also a dab of sticky grease on the back of the pad where it contacts the piston or other side of the caliper can keep it from making noise.

Is the frequency of the hum higher then tire rotation like possibly u joints? U joints are 3-4 times faster then the tire rotation. Front u joint bad can sound like noise from the front possibly. You can check the bolts on the inside of the front axles. I've noticed they can become loose over time. Mine have spacers for a lift kit and after tightening them a few times I put locktight on them. If you're driving in 4wd a lot it could be front u joints. If they're not greaseable or have the plastic white clamp in them they are stock. If they are stock it's time to replace them even if they appear to be okay from a general inspection. I have a 2008 with a similar amount of miles. I just had to do my front u joints this winter and ended up having to do the rear a few weeks ago as well. The fronts were stock and I had to melt them out with a torch. Great idea chevy. New ones are greaseable and if you give them a pump once a year or so it should extend the life a bit over stock.

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Tarcher30

Discussion Starter · #5 · Mar 2, 2022

GBSierraSLE said:
Maybe try to determine if the noise is rpm related or mph related.

Mph

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greygoose

· #6 · Mar 2, 2022

Was the noise there before the new tires?

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Tarcher30

Discussion Starter · #7 · Mar 2, 2022

Tbone Shuffle said:
Is the frequency of the hum lining up with the rotation speed of the tires? Tap your brakes while listening to the noise and see if it changes/goes away. If it does it could be brake related. Sometimes new brakes make noise for a while especially drilled and slotted and sometimes built up grim on the calipers doesn't allow the pads to move smoothly. I've had to clean the sliding areas on calipers before to get rid of brake noise. Also a dab of sticky grease on the back of the pad where it contacts the piston or other side of the caliper can keep it from making noise.

Is the frequency of the hum higher then tire rotation like possibly u joints? U joints are 3-4 times faster then the tire rotation. Front u joiwe have checked u joints it's tire rotation speed. Last year I had to brake very hard coming down a hill with a trailer attached. Int bad can sound like noise from the front possibly. You can check the bolts on the inside of the front axles. I've noticed they can become loose over time. Mine have spacers for a lift kit and after tightening them a few times I put locktight on them. If you're driving in 4wd a lot it could be front u joints. If they're not greaseable or have the plastic white clamp in them they are stock. If they are stock it's time to replace them even if they appear to be okay from a general inspection. I have a 2008 with a similar amount of miles. I just had to do my front u joints this winter and ended up having to do the rear a few weeks ago as well. The fronts were stock and I had to melt them out with a torch. Great idea chevy. New ones are greaseable and if you give them a pump once a year or so it should extend the life a bit over stock.

Tbone Shuffle said:
Is the frequency of the hum lining up with the rotation speed of the tires? Tap your brakes while listening to the noise and see if it changes/goes away. If it does it could be brake related. Sometimes new brakes make noise for a while especially drilled and slotted and sometimes built up grim on the calipers doesn't allow the pads to move smoothly. I've had to clean the sliding areas on calipers before to get rid of brake noise. Also a dab of sticky grease on the back of the pad where it contacts the piston or other side of the caliper can keep it from making noise.

Is the frequency of the hum higher then tire rotation like possibly u joints? U joints are 3-4 times faster then the tire rotation. Front u joint bad can sound like noise from the front possibly. You can check the bolts on the inside of the front axles. I've noticed they can become loose over time. Mine have spacers for a lift kit and after tightening them a few times I put locktight on them. If you're driving in 4wd a lot it could be front u joints. If they're not greaseable or have the plastic white clamp in them they are stock. If they are stock it's time to replace them even if they appear to be okay from a general inspection. I have a 2008 with a similar amount of miles. I just had to do my front u joints this winter and ended up having to do the rear a few weeks ago as well. The fronts were stock and I had to melt them out with a torch. Great idea chevy. New ones are greaseable and if you give them a pump once a year or so it should extend the life a bit over stock.

So I replaced the brakes 2 years ago and went with a power stop set with slotted rotors. The noise is tire speed. Even the diff guy thinks it's tire speed. I had to break hard coming down a hill last year with a trailer attached. Noise started sometime after that. Not sure when. Checked u joints and they are good. I just replaced the front left caliper as well. Still no difference. It sounds very loud at lower speeds. And almost a grind and him when breaking

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Tarcher30

Discussion Starter · #8 · Mar 2, 2022

greygoose said:
Was the noise there before the new tires?

No also just had an alignment as well no cupping on tires.

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greygoose

· #9 · Mar 2, 2022

Tarcher30 said:
No also just had an alignment as well no cupping on tires.

I agree with @Chevy-SS ...... I think it's the tires.

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Tbone Shuffle

· #10 · Mar 2, 2022 (Edited)

Tarcher30 said:
No also just had an alignment as well no cupping on tires.

Can you strap a go pro under the truck and run it to see if it can help identify the noise? Put it by the inside of the axle where it bolts to the diff. There's a bearing on each end of the front diff behind the flange where it bolts to each front axle. If you get a big pry bar in there you can see if there is play in the bearing by trying to pry up on the flange. If there's significant play in it your front axle bearing is bad.

If you can rig it up on flat ground on jack stands so the drivetrain can rotate in gear you might be able to hear it real easy or if you have lift access.
This is a good video on it. I guess a "diff guy" probably would have found that. You would hope.

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Tbone Shuffle

· #11 · Mar 3, 2022

Sometimes bearing sounds only present themselves when the truck is under load with weight on it. Just running it on a lift or turning the tires by hand might not present the noise. My wheel bearings looked fine and sounded fine just testing for play or turning them by hand but the axle nut on the front axle really helps keep them together and from having much play by hand even when they are bad. Ended up swaping both mine out a few months ago. It definitely cured the noise I had. I've done axles. I've basically been rebuilding the front end on my truck too. Lower ball joints, tie rods and UCA's I haven't put on yet. I've done all the u joints. Changed the fluid in the tcase and diffs.

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