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
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.
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.
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.
On 21 Sep 2006 11:52:40 -0700, d firstname.lastname@example.org 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.
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.
On 21 Sep 2006 06:49:44 -0700, d email@example.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.
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).
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