Bad Differential?

Tiny
CECILIA BORES
  • MEMBER
  • 2017 CHEVROLET EXPRESS
  • 2WD
  • AUTOMATIC
  • 60,000 MILES
Hello!

I was driving my van today and after 4 hours driving I started to hear a loud humming and vibration noise. I did not notice any difference or problem when driving.
It was just the noise and some vibration under the co-driver seat when driving at speeds between 20 to 40 mph. I would say it was coming from the back part of the van but my wife was hearing it on her side.

Any chance I can try fixing it by myself? Or should I take it immediately to a mechanic?

Thanks a lot for your help,
Antonio
Wednesday, September 23rd, 2020 AT 7:30 PM

8 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,427 POSTS
Hi,

Is there anything that chances the pitch or sound of the humming? For example, if you make a turn, does it change? If you use the brakes, does it change?

Let me know.

Joe
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Wednesday, September 23rd, 2020 AT 7:34 PM
Tiny
CECILIA BORES
  • MEMBER
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Thanks for you quick answer!
I would say that the only thing that alters the noise is the speed, not the turns or anything else. When it is stopped it is in silence, as I accelerate the sound starts to increase until it becomes stable and loud. Between 20 to 40 mph it also vibrates. When I brake the sound doesn´t decrease continuously but it becomes intermittent (kind of following the revolutions) and the vibration starts again from 40 to 20 m/h.

BTW; I just changed the tires and rims about 1,500 miles ago.
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Wednesday, September 23rd, 2020 AT 8:03 PM
Tiny
JACOBANDNICKOLAS
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Hi,

Make sure the wheels are tight. Also, when you drive it next, in a safe area, make sharp turns left and right to see if it makes any difference. I'm thinking it could be a wheel bearing. One other thing, make sure the tires are worn evenly and there is no evidence of a shifted belt.

Let me know what you find.
Joe
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Wednesday, September 23rd, 2020 AT 8:11 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Can you please shoot a quick video with your phone so we can hear the noise? That would be great. You can upload it here with your response.
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Thursday, September 24th, 2020 AT 4:41 PM
Tiny
CECILIA BORES
  • MEMBER
  • 7 POSTS
Thanks for your suggestion. I upload two videos here, one from the inside and another from the outside. Hope this helps you to identify the origin of the sound. It doesn´t change when turning, only when speeding or braking. The wheels and tires seem to be fine.
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Saturday, September 26th, 2020 AT 10:23 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,427 POSTS
Hi,

The sound certainly sounds like a bearing. Now, you said it seems to be coming from the rear. Do me a favor. First, look behind the tires/wheels on the rear and see if anything appears to be leaking. If it is in the rear, it could be an axle bearing. Most times it will cause a leak of gear lube from the differential and leave evidence.

Next, confirm the rear differential is full of oil (gear lube). I attached a pic below and circled the fill plug. It is on the passenger side of the differential. Remove the plug and fluid should be to the top of lower portion of the plug threads. Also, the part that I highlighted has a bearings and a seal. See if anything is wet there.

____________________________________________________

Also, take a look through this and try what is suggested.

_____________________________________________________

Bearing Noise
Faulty bearings produce a rough growl or grating sound, rather than the whine typical of gear noise. Bearing noise/hum will pulsate at a constant vehicle speed. This indicates a bad pinion or a bad rear axle side bearing. This noise can be confused with rear wheel bearing noise. Inspect and replace the bearings and the affected components as required.

_________________________
Rear Wheel Bearing Noise
A rough rear wheel bearing produces a noise which continues with the car coasting at low speed and the transmission in neutral. The noise may diminish some when the brakes are gently applied. The noise may also change when performing side-to-side maneuvers with the vehicle.

A rough/noisy rear wheel bearing can be heard by spinning the rear wheels by hand and listening at the hubs for the noise. Inspect and replace the bearings and the affected components as needed.

____________________________________________________

Since there doesn't seem to be a change when turning, it's likely coming from the rear of the vehicle. However, in addition to rear wheel bearings, there are several others.

Let me know what you find or if you have other questions.

Take care,
Joe
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Saturday, September 26th, 2020 AT 5:24 PM
Tiny
CECILIA BORES
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Hi!
Thanks a lot for your help. We decided to take it to the Chevrolet dealer because it is our only car and we need it.

They said the sound was way too loud for a wheel bearing. Apparently it is the differential, and gave us a budget of $3.700.00 for the labor and parts (for a used differential).

Does this sound okay with you? I think this is extremely expensive, I am not sure I will be able to afford the reparation.
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Friday, October 2nd, 2020 AT 11:24 AM
Tiny
KEN L
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I would take it to a shop that will install a used unit would save money. The rear differentials do not go out often so used would be your best bet in my opinion. Here is the instructions on how to change out the differential in the diagrams below in case you want to do the job yourself. Check out the diagrams (below). Please let us know what happens.
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Saturday, October 3rd, 2020 AT 11:05 AM

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