Rear End Noise 2003 Suburban

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I am traveling with my 2003 Suburban 1500 5.3. I started noticing a whirring noise coming from the rear end while under load above 45 mph. Noise goes away on deceleration and low speed only audible while under load and consistent with wheel speed, not rpm. Sounds like pinion gear type issue. I am towing about 6k lbs and have done a lot of mountain towing this trip. There is moisture on the pinion seal area, but no evidence of dripping ar anything major yet. Is this anything to be majorly concerned about yet? I have 1800 miles more to get home. Anything else I can look for in a parking lot to diagnose further? Thinking to check and top off fluid. Is this doable in a parking lot without a jack. Any other advice?
 
I am traveling with my 2003 Suburban 1500 5.3. I started noticing a whirring noise coming from the rear end while under load above 45 mph. Noise goes away on deceleration and low speed only audible while under load and consistent with wheel speed, not rpm. Sounds like pinion gear type issue. I am towing about 6k lbs and have done a lot of mountain towing this trip. There is moisture on the pinion seal area, but no evidence of dripping ar anything major yet. Is this anything to be majorly concerned about yet? I have 1800 miles more to get home. Anything else I can look for in a parking lot to diagnose further? Thinking to check and top off fluid. Is this doable in a parking lot without a jack. Any other advice?
Checking the fluid about is all you can do , maybe wiggle the drive line at the differential there isn't much you can do. When was the last time you changed the fluid?
 
Might be the beginning or the bearings going out on the pinion gear.. I would do a fluid change first and see ...
 
Pinion bearings are no good. I would be very cautious, especially towing. Make sure the fluid stays full
 
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Maybe post your location and approx route? Might be BITOG members along the way who might help if needed?
 
If its truly a whirring noise ! carrier bearing , howling noise pinion bearing ? or axle bearing ?
 
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If its a 4wd take a look at the transfercase and fluid level in it. I could swear that the noice of our Suburban came from the rear when driving but it was the transfercase that got a leak from pump rub and i run it empty for a long time before it started to make noice.
 
There should be room to wiggle under there and check/top off the fluid without jacking it up.

This likely isn't your problem, but I had the pinion nut loosen up on an '87 Caprice. It was awhile ago, but I think it was noisy so I checked underneath and found a bad pinion leak. The nut had backed off, so the slop in the pinion yoke took out the seal. It was fun trying to tighten it laying underneath with a breaker bar. A neighbor loaned me an electric impact to finish the job.

From what I remember, this was not a "Hmm. I notice a whirring sound above 45; I wonder if it will make it another 1800 miles" kind of noise. It was more an automotive version of a playing card in the bicycle spokes.
 
Sounds like gear noise. Pinion bearing would growl all the time. I would check the pinion preload in case the pinion nut loosened. I had a pinion nut loosen and made the exact noise as you describe. I was able to silence most, not all of the noise by adjusting the pinion preload, I was lucky.This is a very critical adjustment , so don't just go torqueing the pinion nut as you can really screw things up if done incorrectly. I used a 1/4 drive "pointer" style torque wrench because the spec is very small, around 8-14 inch pounds of preload. There is a lot of prep work needed before taking an accurate reading. This adjustment should also be done when the pinion seal is replaced.
I would atleast check the gear oil and top off. It would have to be pretty low to create gear noise. If you didn't over endulge over the holidays, you should be able to slide underneath.
 
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Sounds like gear noise. Pinion bearing would growl all the time. I would check the pinion preload in case the pinion nut loosened. I had a pinion nut loosen and made the exact noise as you describe. I was able to silence most, not all of the noise by adjusting the pinion preload, I was lucky.This is a very critical adjustment , so don't just go torqueing the pinion nut as you can really screw things up if done incorrectly. I used a 1/4 drive "pointer" style torque wrench because the spec is very small, around 8-14 inch pounds of preload. There is a lot of prep work needed before taking an accurate reading. This adjustment should also be done when the pinion seal is replaced.
I would atleast check the gear oil and top off. It would have to be pretty low to create gear noise. If you didn't over endulge over the holidays, you should be able to slide underneath.

When coasting the bearings are not really under a load. Under power they certainly are.

OP I would still unload the drive train and check to see if there is any slop in the pinion.
 
The OP said he hears the noise while the rear end is under load. While under load the way the pinion engages the ring gear it will create a thrust load towards the drive shaft loading the larger pinion bearing. Under decel the reverse is true. A loose pinion nut will cause noise on decel because the pinion thrust is towards the diff cover allowing the gears to lose their setup alignment and this creates noise.

Since the OP isn't experiencing noise on decel I wouldn't suspect a backed off pinion nut.

If it were carrier bearings you would most likely hear noise all the time and would usually get louder while going around a curve which depending on direction would load one carrier bearing more than the other. while under load the carrier is being thrust away from the pinion though so it's possible to make noise only under power, but much less likely than a pinion bearing.

Outer axle shaft bearings you would expect to hear all the time.


Like was mentioned previously, unless you have messed with the rear diff recently or blew up the G80 locker (if you have one) then don't overlook the transfer case. The early transfer cases if its 4wd have a nasty habit of breaking a wear tab and the oil pump in the transfer case will rub against the case until it eventually wears through and will allow it to go dry eventually.
 
If its a 4wd take a look at the transfercase and fluid level in it. I could swear that the noice of our Suburban came from the rear when driving but it was the transfercase that got a leak from pump rub and i run it empty for a long time before it started to make noice.
Yep, pump rub is at least worthy of consideration here. The ironic thing is Borg Warner had the same problem with the 1356, except in that case it's a single arm that fails internally and you never see it.

I just found it fascinating that over the span of ~20 years both BW and NP/NVG had nearly identical problems just keeping a light oil pump located....

...sorry, ramble mode off.....
 
When coasting the bearings are not really under a load. Under power they certainly are.

OP I would still unload the drive train and check to see if there is any slop in the pinion.
The ring and pinion noise can vary under loads but the pinion bearing is still spinning and if its rough, it will always make noise. Every pinion bearing I came across made noise all the time, not like a wheel bearing.
 
Yep, fill it up. Leaks often occur at the wheel bearing seals. Look at the inside of the rear tires for leakage. The good news is I have seen Chevy 1/2 ton rear ends behave once filled back up.
 
Manual for 1500 suburban says diff fill should be between 5/8 and 1-5/8. I am at 1-5/8, so I will add to try to bring it closer to the upper level ofv5/8 from fill hole and see if that helps.
 
I am traveling with my 2003 Suburban 1500 5.3. I started noticing a whirring noise coming from the rear end while under load above 45 mph. Noise goes away on deceleration and low speed only audible while under load and consistent with wheel speed, not rpm. Sounds like pinion gear type issue. I am towing about 6k lbs and have done a lot of mountain towing this trip. There is moisture on the pinion seal area, but no evidence of dripping ar anything major yet. Is this anything to be majorly concerned about yet? I have 1800 miles more to get home. Anything else I can look for in a parking lot to diagnose further? Thinking to check and top off fluid. Is this doable in a parking lot without a jack. Any other advice?
Any luck?
 
Huh, cant recall having either of my old gmc's trucks do that. Perhaps just change the gear oil with 140 like I do. How many miles and what are the gear oil intervals.
 
I've seen the pinion yoke nut loosen on some vehicles, which allows the pinion gear to walk up the ring gear and make whining noise. Get under the truck and shake the driveshaft at the rear axle pinion yoke, see if it moves at all. If the pinion yoke nut is loose, remove it...clean the threads...apply Loctite Red, and torque it to spec.

Aside from this, Lucas 85W-140 is the "quietest" hypoid gear lube I've had luck with on whiny differentials. A drain of what's in there and fill with this would be a low-cost experiment.
 
Any luck?
Just took vehicle to mechanic... Their diagnosis is carrier bearings going bad, and it is very slight, but should be done. They said they would replace pinion bearing, pinion seal, carrier bearings and wheel bearings for 1500.00. I also have rear main seal leak (Different thread) for 1350.00 . I only have budget for 1 of those projects now. I am thinking to have them do rear main (seal since the general consensus on that thread was it is not a driveway type project) and try to tackle rear end work myself, since quality bearings are not expensive. Anything I should be concerned about trying to do this one on my own?
I could check wear patterns on ring gear of I did it on my own to rule out ring and pinion issues. mechanic did not pull diff cover. Used stethoscope to listen to bearings.
 
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