Differential service - slight whining

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blert

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3.73 non-ls

Finally got around to popping the pumpkin open and changing the fluid. It is so much quieter now but I can still hear a little bit of whining when the rear window is down. It is not loud (anymore). I am assuming this is typical? Would a heavier oil quiet it down more? I used Mobil1 75w-90LS.
I used a LubeLocker gasket so have no problem opening it back up and putting in 75w-140 if it will help. Thanks.

Edit:
The old oil was nasty, almost milky. Not much on the filler plug magnet but it was caked with a white, milky sludge. As far as I know it had never been serviced before.
 

DILLARD000

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Assuming 2WD rear differential?
2001 ExST OwnersManual calls for
80w90 in OpenSlip Diffs & 75w140+Additive in TracLok\LimitedSlip Diffs.
MilkyWhiteSludge indicates water in the oil; has the truck ever been driven thru deep water or flooded?
I'd open cover & fully drain the Diff one more time,
give it a good spray down with BrakeCleaner, let that drain+dry,
refill with OwnersManual spec 75w90.FullSyn\80w90.FullSyn or 75w140.FullSyn+Additive,
but use a premium HiTemp\HiPressure brand like AmsOil or TriboDyn.
If that don't quiet the whine, then a rebuild or new Diff may be needed.
 

blert

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Correct, 2wd.

Never been flooded but I have driven through some deep water a couple few times. Nothing prolonged, just a street that would flood during heavy rain and me having to get through it. It was hilarious to watch the folks get stuck halfway through though.

Probably a good idea to drain it out again anyway just to make sure all that crap is out.

Been considering grabbing a rear end from the junk yard and rebuilding it then do the swap.

Edit: off topic but have been wanting to ask you... Are you a programmer? I ask because you use a lot of PascalCase.
 
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EddieS'04

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MilkyWhiteSludge indicates water in the oil; has the truck ever been driven thru deep water or flooded?
Ditto.....make sure the vent hose is still on the top left side of the diff. Also that it is tied off as high you can, leaving enough slack for suspension movement.
Also if you have any leakage at all on the axle seals. Water will migrate.
I completely ruined a dodge van rear end. Too much high water. Cost complete salvage yard replacement. Thought I was safe. Never let off the throttle as so the auto trans front pump vent. would not suck up water.
The problem was the rear axle vent was only a loose fitting cap, not a hose.
 
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blert

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Hose was brittle but attached properly and clear. I replaced it.
 

DILLARD000

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...been wanting to ask you... Are you a programmer? I ask because you use a lot of PascalCase.
Astute observation there.
IndustrialInstrument+Controls designer\programmer\builder in a previous life; retired many years now.
The "PersonalPreference" for "PascalCase" is likely the result of "LimitedSpace" in "OldProgrammingApps"
& some "AncientGermanDNA" expressing itself with "MultipleCompoundWords".🤓
 
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kmartin

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One of your bearings could be going bad. I had noice coming from differential and it was a pitted carrier bearing.
 

blert

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If I decide to jump face first into replacing the bearings (pinion, carrier, and wheel) of this differential do I need deal with adjusting the backlash and pinion depth or can I leave it shimmed exactly the same? Assuming that the gears are all in serviceable condition.

I have no experience with this. It doesn't look terribly difficult but looks like it takes a lot of time (got that) and special tools (don't have). Better off having a shop do it?
 

kmartin

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If I decide to jump face first into replacing the bearings (pinion, carrier, and wheel) of this differential do I need deal with adjusting the backlash and pinion depth or can I leave it shimmed exactly the same? Assuming that the gears are all in serviceable condition.

I have no experience with this. It doesn't look terribly difficult but looks like it takes a lot of time (got that) and special tools (don't have). Better off having a shop do it?
To me, it is up to you if you want to try doing it or get a shop to do. I get a shop to do most of my stuff, because I don't have much time to do stuff if you have to take lots of stuff apart. Plus, confidence level isn't that high. I just got them to replace all the bearings and switch the open carrier out with a limited slip one, since they needed to take all that apart. If you do have a limited slip, depending on the mileage, you might as well replace the clutches.
 

blert

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Meh, a little whine is ok.... mine does it on coast for 121K miles...
Figured as much. I'll put it on the list.

My plan is to give it a week or two (I don't drive it much) and then change the gear oil again. In the mean time, I will service the transmission with a new filter and pan (with drain plug). Run that for a week or two and dump the trans fluid again.

Sooner or later something is going to give in this truck and I don't want to go dropping a ton of cash on the diff if the trans wants to give out first.
 

DILLARD000

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Does anyone have experience using TriboDyn gear oil; they make claims to be able to quiet pitted bearings?
 

blert

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Visited their website. The price of the motor oil is stupid. The gear oils is expensive but not totally out of line with competitors. Might give it a go unless someone here comes back with a warning.
 

swshawaii

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@blert

FWIW, I have the same 3:73 open "46" axle code. I also found milky colored gear lube when I removed the cover at around 60,000 miles. Man that stuff STINKS. I don't "believe" it was ever submerged in water. Magnet had typical soft grey colored sludge on it, but no large metal shavings. Decided to add a T/A Performance (Moser 7106) 8.8 cover simply because it looked cool and nothing more. Keep trying to convince myself the small fluid capacity increase and the drain plug made it worth the $150 expense. LOL Also used 75W-90W hoping for slightly better MPG and the fact I don't tow. Did quite a bit of research and found the gear lube test linked below reportedly from an independent lab. Must say I have no complaints using the Amsoil Severe Gear, but I didn't have whine issues before. May be worth a read if you are undecided. GL

http://www.syntheticwarehouse.com/brochures/g2457_gearlube_study.pdf
 

blert

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Interesting read, thanks. Good to see the Mobil1 I put in fared better than most.

Edit:
Is there still an Amsoil rep lurking around these forums somewhere? Got name so I could PM them?
 
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swshawaii

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Used to be an Amsoil dealer on Todd's site. Don't see sponsors here. I believe Todd uses Amsoil SG too. May want to PM him. (again)

Much as it's "right" to buy from a sponsor, shipping costs will likely be prohibitive unless close by.
 

blert

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I know I saw some at one of the big three (advance/autozone/oreilly's). Can't remember which though. Was at Napa earlier today so it was not them. I'll check it out this week sometime.
 
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