Pinion Bearing Failing?

[richamc01]

I have a 99 T4R. When I'm driving at highway speeds (anything over 50 MPH) and I let off of the gas to decelerate, I hear a whine. It's hard to tell if it is coming from the front or the back but I believe it is coming from the front. I originally thought it was a belt making the noise as I had just installed a new timing belt and replaced all of the other belts in the process. After doing a bit of searching, it seems as though my pinion bearing is what would be causing this noise.

The noise gets louder the faster I go and it only happens when I let off of the gas to decelerate. The noise goes away as soon as I touch the accelerator. I don't hear it at all when I'm driving slower than 40 MPH and decelerate.

Are there other ways to diagnose and how long can I drive with this noise? I have a 5 hour drive coming up next week and I'm not sure I have time to get it fixed before I go.

 

[Acorn22]

Yep I had this same exact problem as you did (mine was the rear diff), and replacing the 3rd member took care of it. You're fine to keep driving on it, it will just keep getting gradually louder with the more miles you put on it, but there is no immediate danger or anything like that... To isolate if it's the front or rear, I would just jack the runner up and put it in drive in 2wd to see if you can hear it, if not then it should be in the front diff.

 

[Kanoe]

It wouldn't hurt to check the level of gear oil in those diffs before you go, particularly the rear. Top up or change as needed. Takes minutes to do.

 

[T4R2014]

Sounds like it. Mine only does it when I’m on the accelerator. With that said, I bought it like that and that was 15k ago. It sounds annoying as hell above 60 but whatever. Fill it with 85W-140 and start saving.

 

[Cree]

Same problem, same mile per hour range. You can drop your rear drive shaft and it should go away. As stated it can last forever like that, it's just annoying.

 

[richamc01]

Thank you all for the info! I'm glad to hear that I'll still be good to drive on it for now. I think I read somewhere that since it whines during deceleration, it's the front pinion bearing. Does this sound right?


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[Nate_GB]

Thank you all for the info! I'm glad to hear that I'll still be good to drive on it for now. I think I read somewhere that since it whines during deceleration, it's the front pinion bearing. Does this sound right?


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Sounds reasonable. But in reality, it won't really matter which bearing it is. You'll want to do a full rebuild and new pattern setup while you're in it anyway. When it comes apart, you should be able to look at the bearings and immediately know which one was failing. If it's bad enough to cause a whine, it'll most likely show its wear by being pitted.

 

[Greaser]

I'm trying to diagnose if I have this same issue or something else like a rear wheel bearing. The noise I get...it's less of a whine and more of an oscillating rumble sound that doesn't change with engine RPM or when I put it in neutral at those speeds.

Low in pitch, gets louder/quieter in a rhythmic pattern every few seconds, not noticeable at lower speeds, doesn't seem to change under power.

Can't feel it in the wheel or in the tranny/transfer case when I put a hand on the levers. Happens around 70mph. Doesn't seem to change when I swerve though I'm not swerving too hard at 70mph.

Tires are pretty much new though the truck is also new to me so IDK if it did the same thing with prior tires (will swap with a buddy this weekend)

I'm thinking it's wheel bearings but sounds like pinion bearing could be the issue as well...how does your sound compare to my description?

 

[HiLife]

I had a wheel bearing go bad. It's a deep rumbling vibration. As the miles ticked it got more pronounced. Loading the wheel bearing (applying the brakes slightly, turning left or right) make the rumbling go away. Driving straight at any speed was irritating after a while.

 

[brillo_76]

I'm trying to diagnose if I have this same issue or something else like a rear wheel bearing. The noise I get...it's less of a whine and more of an oscillating rumble sound that doesn't change with engine RPM or when I put it in neutral at those speeds.

Low in pitch, gets louder/quieter in a rhythmic pattern every few seconds, not noticeable at lower speeds, doesn't seem to change under power.

Can't feel it in the wheel or in the tranny/transfer case when I put a hand on the levers. Happens around 70mph. Doesn't seem to change when I swerve though I'm not swerving too hard at 70mph.

Tires are pretty much new though the truck is also new to me so IDK if it did the same thing with prior tires (will swap with a buddy this weekend)

I'm thinking it's wheel bearings but sounds like pinion bearing could be the issue as well...how does your sound compare to my description?

How many miles on your 3rd member? Did it ever run low on gear grease?. As mine 3rd member rumbles at 70mph. However I believe mine has some heavy wear from running low on grease a few times. Being I have a spare. I just basically seeing how long it will last. I put 100% lucus heavy duty oil stabilizer in the 3rd member to make it less noisy.

Running low on gear grease can damage the pilot bearing plus I am sure my gears are warn as well with 260k on the odometer. In the rust belt the axle housing can rust thin and leak gear grease. So if people arent watching they can run it out of grease and really do damage to the bearings.

If you drain your gear grease out to you have a lot of metal fillings on the magnet in the plug as that's another sign of member damage. As metal shavings and small chunks should not be there. Just a real lite metal paste sorta like the transmission magnets would be considered normal.

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