Humming noise in rear end

99 Blazer driving hum,noise - Blazer Forum - Chevy Blazer Forums

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Dec 31, 2007 - 99 Blazer 4x4 has constant noise-humming that occurs non-stop and increases and ... Sounds like it is coming from rearend but not 100% sure. 99 LT 4x4 Rear End Whine
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rear end (I use and electronic stethoscope to find all that)
but rear end. is a big place..
bad U-joints top that list (repeat)
bad axle bearings.
brakes bad, there. or the warning devices there for early brake warn.
bad 3rd member, gear sets or bearings in same or pinion.

my guess is car is moving right>
if not moving ,its dying rat up in there.or loose parts.

clean battery cables very good.use grease on ends andposts.slice insulation back a bit to see if there is white powder corrosion inside if so replace cables.but bet cleaning posts and ends will do the trick use grease.

grease ur differential ur rear end get underneath find all ur grease zerts and ask a shop how to grease ur rear end

If this noise is only while moving, I found a possible solution some time back. On the right side of this car (if I remember right) mounted on the subframe, there is a carrier bearing on that axle shaft. On this particular car, the bearing was still good but the u-shaped bracket it sits in was broken which allowed for humming and vibration. There was also a bad motor mount which also created a "humming" (I guess you could call it) and that was there while the car was stopped and running. The "humming" would change with the rpms. I hope this has helped to pin point your problem. Please let me know how this worked out for you or if there's anything else I can help you with. Thanks and good luck!

• That hum sounds like a wheel bearing or HUB. When you turn to the right your swaying the weight of the vehicle to the left and this makes things quieter on the right side when turning to the right.

• Jack the front end of the truck up and place your hands on opposite ends of the tire (diagonally) and look for any play. This is a way to test for a bad bearing. Do this for both wheels.

• A stuck caliper could do this as well. So could that rear differential. I would start with a good check of the bearings first. I suspect the passenger side front, but check every wheel.

• If you have any comments please feel free to leave them here.
• Hope this helps and thank you for using FixYa.

Regards, Tony

Unless it is a hub bearing, yes, it could be a CV. If you can, look under the car and right behind the tire/hub assembly, you should see a rubber boot on the end of a shaft. Check the boot for a possible rip in it. If it is ripped, you'll see grease all over the place. Check the other end too, this end is attached to the transmission and will have the same appearance if damaged.

Sounds like the rear end itself, most likely if u have high mileage.

It sounds like you have a tear in the CV Boot on right joint. You will most likely need to replace that joint. If you are noticing grease coming out, then you most likely have dust or dirt that has got into the boot creating the humming sound. If the joint is not damaged, you may get lucky and only have to replace the boot and regrease the joint.

i had the same problem, i found out that both rear torque arm bushing are filled with liquid grease, when they go bad all the grease comes out of them and then the metal sleeve inside the bushing starts the hit the bolts, when you hit a bump. that was the loud noise, that i had.