HELP, rotational/humming noise at all speeds.

[itschrisb]

https://vimeo.com/186443776


I just bought this 98 Limited with 232k and it has a pretty noticeable humming noise anytime the vehicle is moving. It starts as soon as the vehicle starts rolling doesnt matter if its in neutral or drive. Left or right doesnt change anything so im ruling out wheel bearings unless theyre both blown. The only difference in sound is when you let off the gas and just coast, the noise is still there it just has a different tone to it.

There is a slight vibration in the front when you hit about 60mph but the front tires are worn and it needs steering rack and sway bar bushings so Im not very concerned about the vibration. The truck still drives straight and smoothed even at 70mph it just makes this annoying sound.


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[itschrisb]

https://vimeo.com/186445446

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[JWaldz]

[MENTION=147219]itschrisb[/MENTION]

Based off your description and the video, I'm willing to bet it's your u-joint on the rear of the driveshaft. Pretty common wearing part as most people never lube it via it's zerk/grease fitting. (especially before/after offroading).

I can only hear the sound and it's usually never truly clear through video so, is it a loud vibration that also sounds a bit of grinding as well? Also, a great indicator of the u-joint being the problem is the fact that it quiets when not under load, and gets louder the more you put it under load (step on the gas).

Crawl under your truck and give the rear of your driveshaft by the u-joint some movement with your hands. It shouldn't typically have any large movement. With a faulty one or one that's dead, it will have play.

 

[itschrisb]

[MENTION=147219]itschrisb[/MENTION]

Based off your description and the video, I'm willing to bet it's your u-joint on the rear of the driveshaft. Pretty common wearing part as most people never lube it via it's zerk/grease fitting. (especially before/after offroading).

I can only hear the sound and it's usually never truly clear through video so, is it a loud vibration that also sounds a bit of grinding as well? Also, a great indicator of the u-joint being the problem is the fact that it quiets when not under load, and gets louder the more you put it under load (step on the gas).

Crawl under your truck and give the rear of your driveshaft by the u-joint some movement with your hands. It shouldn't typically have any large movement. With a faulty one or one that's dead, it will have play.

Just crawled under there and gave the driveshaft a good yank and tried spinning it there is zero free play in the shaft or joint its rock solid. The PO did apply grease to the outside of the joints and changed all the fluids. Not sure if he greased inside the joints at all though or what kind of fluids he used.

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[Cree]

Could be the u-joint, could be a carrier bearing, could be a noisy R&P. I have a similar noise. I'm suspecting the carrier bearings on mine.

 

[nevada]

I cant tell by the video, but based on your description, I would guess the rear differential. either bad bearings, or a poor set up if gears were changed.

 

[itschrisb]

Could be the u-joint, could be a carrier bearing, could be a noisy R&P. I have a similar noise. I'm suspecting the carrier bearings on mine.

Anyway to check these individually to rule them out?

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[badattitude]

Sounds like a Pinion bearing to me. Unfortunately, there's no way to confirm. If the axel seals leaked at any point where the rear diff fluid was too low it can leave the Pinion bearing with out gear oil and that can lead to Pinion bearing noise.

Is the vibration at 60mph in the steering wheel? If so it may be caused by improper balancing. I'm sure these truck's wheels are lug-centric meaning they require a finger-plate adapter to balance. Some tire shops have a hard time believing me however, when I balance with a finger plate adapter there are fewer weights and I don't have a vibration at 60mph.

 

[itschrisb]

Sounds like a Pinion bearing to me. Unfortunately, there's no way to confirm. If the axel seals leaked at any point where the rear diff fluid was too low it can leave the Pinion bearing with out gear oil and that can lead to Pinion bearing noise.

Is the vibration at 60mph in the steering wheel? If so it may be caused by improper balancing. I'm sure these truck's wheels are lug-centric meaning they require a finger-plate adapter to balance. Some tire shops have a hard time believing me however, when I balance with a finger plate adapter there are fewer weights and I don't have a vibration at 60mph.

Is the only way of fixing it to replace the pinion bearing? I really have no idea if the axle seals have ever leaked. I can check back through the service records the guy gave me to see if its been done at any point.

Yea the vibration is coming from the steering wheel its not violent but its there. The tires have uneven wear on the outside of the tires compared to the inside so im sure that isnt helping.

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[nevada]

Sounds like a Pinion bearing to me. Unfortunately, there's no way to confirm. If the axel seals leaked at any point where the rear diff fluid was too low it can leave the Pinion bearing with out gear oil and that can lead to Pinion bearing noise.

Is the vibration at 60mph in the steering wheel? If so it may be caused by improper balancing. I'm sure these truck's wheels are lug-centric meaning they require a finger-plate adapter to balance. Some tire shops have a hard time believing me however, when I balance with a finger plate adapter there are fewer weights and I don't have a vibration at 60mph.

you can pinpoint the noise using a stethoscope.

Is the only way of fixing it to replace the pinion bearing? I really have no idea if the axle seals have ever leaked. I can check back through the service records the guy gave me to see if its been done at any point.

Yea the vibration is coming from the steering wheel its not violent but its there. The tires have uneven wear on the outside of the tires compared to the inside so im sure that isnt helping.

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yes. though, if you end up doing that, I suggest doing ALL the bearings.

 

[itschrisb]

you can pinpoint the noise using a stethoscope.



yes. though, if you end up doing that, I suggest doing ALL the bearings.

How would I go about doing the stethoscope method? Where exactly would I need to listen to pinpoint the pinion bearing?

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[nevada]

How would I go about doing the stethoscope method? Where exactly would I need to listen to pinpoint the pinion bearing?

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you would listen to many different points on the differential, and even out at the axle ends. you will figure out right away where the noise is coming from.

as close to the pinion flange as you can get, without touching any of the moving parts, to check for the pinion bearing.

but really, check it everywhere, then make note of where the noise is the loudest,.

 

[Cree]

How would I go about doing the stethoscope method? Where exactly would I need to listen to pinpoint the pinion bearing?

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[JWaldz]

If your pinion bearing is shot in the rear diff you would have likely noticed when trying to move the driveshaft to troubleshoot the u-joint. However, since it wasn't exactly what you were going after, I'd test for pinion bearing play itself. It's easy, and I could explain how to do it, but you're better off just looking up how to diagnose it on youtube and it will show you exactly what to do and what to look and listen for.

https://youtu.be/LzOyWNyEcZs

A couple things about the video that it doesn't detail is you don't have to have the vehicle off the tires. Also, when testing the pinion bearing I like to test for play in various different positions of the pinion. Meaning, I test for play.. If none, I drive a tad to rotate the driveshaft/pinion some (or if the tires are off the ground, just rotate the tire a little to rotate the driveshaft). Then, test it again. Repeat a couple times. This assures that the pinion isn't resting on the bearing in a weird position not allowing it to move. Of course, you DON'T want any movement. You can see in the video that even that minor of movement can cause issues. Especially if it's "popping/clunking" like it is in the vid. If after testing it in the different positions and it's not moving, I say it's fine.