Rear End whining

I have a 98 Silverado 4x4 with a lot of miles on it. I notice that under acceleration the rear end starts whining around 35mph and continues from there. It does lessen a little bit at higher highway
speeds. If you let off of the gas and just coast the sound goes away until you hit the gas and it start whining again. A friend told me it may be the pinion bearing but I wanted some other opinions. Anyone have any other ideas? Is there anything I can check before I start just replacing parts? Thanks
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Check the fluid level. If it's real low you found the cause, now you just need to fix the problem. You can do all kinds of guessing, but you'll have to open it to find the problem. Could be a bearing like your friend said, but it could also be a worn or damaged ring and pinion. Bite the bullet and take a look. Whatever you do, don't just keep driving it. If the bearing is brinelling chips of metal are being circulated through the rest of the assembly. Make that chips of very hard metal.
One more thing; If there is major damage you might consider replacing the entire rear axle. Since it's a 4X4 you need to find one with the correct gear ratio. Around here you can find them for 300 to 500 dollars if you do some serious searching. Rear axle parts and labor bills add up very fast. My neighbor had the carrier bearings and the pinion bearings replaced in an S-10. Cost over $750.
Al
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If it is whining from low fluid, it likely has damaged gears or bearings anyway. Depending on how bad the noise is the serious of the matter varies. I have seen rear axles with worn ring and pinions that were a bit noisy go for many many years with regular lube changes. (the rear axle in my 89 4x4 burb with 180K mile is a bit noisy at certain speeds and has been for years) Most neglect rear axle and never check fluid let alone change it. I change my drive axle fluid every 20 to 30K in my vehicles and a bit more often in severe duty or when they are getting a bit worn. If you just drive it and do not change fluid, it is just a question of time before it gets worse. Just about all the rear end failures I have seen have either been after a very long service life with good maintainance or after a much shorter life after poor maintanice and/or abuse. If you have a 10 bolt axle in a 1/2 ton it is not the strongest axle to begin with and need good care for long life. A 14 bolt 9.5 or 10.5 is a lot more tolerant of lower maintance and abuse. ----------------- TheSnoMan.com
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Thanks for the help everyone. I am going to dive into it this weekend and at least pop the cover and take a look. I do know that the seal has been replaced and it still drips fluid now and again. I bought the truck cheap and it came with these problems. Will see what I find when I dig in this weekend.
Doug
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On 21 Sep 2006 11:52:40 -0700, d snipped-for-privacy@hotmail.com wrote:

Which seal? If it was the pinion seal and they did not properly mark and reinstall nut to correct positions they could have damaged pinion bearing which would change gear mesh and noise. ----------------- TheSnoMan.com
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Sorry I should have answered this better. From what I can see the differential cover gasket was the only thing changed on the rear end. I dont know if the pinion seal was changed or not. My cousin that I bought it from is oversees in Iraq and a little hard to get ahold of.
Doug
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On 21 Sep 2006 06:49:44 -0700, d snipped-for-privacy@hotmail.com wrote:

Pinion bearings tend to be noisy all the time (like carrier bearings) but your freind is not all wrong here. Pinion bearings maybe a little worn which would change the mesh of pinion and ring gear and cause your noise. If this is the case, it would go away when you coast like yours does. Ring and pinion could be worn out too as it can happen especailly if it has not been serviced regularly. ----------------- TheSnoMan.com
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d snipped-for-privacy@hotmail.com wrote:

If it's whining on "drive" (which is when you are accelerating), but not on "coast" (which is when you have your foot off the gas), you may have a combination of bearing problems and gear problems, but rest assured that you will not be able to get rid of the whine noise by simply replacing the bearings. Once a gear set has developed a "whine", a new gear set which is "set up" properly is about the only thing that will fix it. If I were you, I'd check the bearings.....fix "that" properly, which includes setting the pinion bearing preload and side bearing preload, ensuring that you have a reasonable amount of backlash (.005"-.008" will be where you want to be) and then live with whatever whine you have (the noise will have no effect on longevity).
Ian
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Seconded!
wrote:

-
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wrote:

THis is pretty much true. Depending on the "damage" sometimes you can quiet them a it by adjusting them but they will never be as quiet as new though. ----------------- TheSnoMan.com
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SnoMan wrote:

Oh geez! Thanks "so" much for your vote of confidence.
Ian
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Go forth young fellow and seek your fortune. You have the blessings of the Snojob.
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On Fri, 22 Sep 2006 03:00:24 GMT, aarcuda69062

THere always has to be a wise ass. ----------------- TheSnoMan.com
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That's my point.
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