How to on Changing Rear Diff Fluid? Rear whine at 40-50mph...

[SgKukov]

Hey Guys,

I have the dreaded rear end whine... so far it seems like it just started. Its a low whine at 40-50 and goes away when you let off the gas. From what i've read i'd really like to try and tackle this now before any clutches wear out or anything.

I have an 03 AWD XLT 4.0 w/ tow package.. i'm assuming this is an LSD w/ 3.73 gears?



Are there any nice picture or video how tos on changing the rear diff fluid? i've read a few write ups... but i like fancy pictures. Any help would be appreciated.

Its FREEZING out but i'd really like to change this fluid before things get worse. I just bought this car w/ 95k on it... so far i really like it. I'd like to keep liking it

 

[JoshMcMadMac]

Just bypass the seal change information:
http://www.explorerforum.com/forums/showthread.php?t=326205

 

[imp]

Hey Guys,

I have the dreaded rear end whine... so far it seems like it just started. Its a low whine at 40-50 and goes away when you let off the gas. From what i've read i'd really like to try and tackle this now before any clutches wear out or anything.

I have an 03 AWD XLT 4.0 w/ tow package.. i'm assuming this is an LSD w/ 3.73 gears?



Are there any nice picture or video how tos on changing the rear diff fluid? i've read a few write ups... but i like fancy pictures. Any help would be appreciated.

Its FREEZING out but i'd really like to change this fluid before things get worse. I just bought this car w/ 95k on it... so far i really like it. I'd like to keep liking it

If you have the limited-slip, rest assured worn clutch discs make no noise. Lacking appropriate friction-modifier compound in the fluid often allows the clutches to jerk a bit, little noise generated, only when moving in other than a straight-ahead direction.

Whine occurring upon application of power- accelerating or moving ahead at speed, which disappears or lessens quite noticeably is invariably generated by the gear teeth. The likely causes are:
low fluid level in axle
gear teeth damaged by debris circulating in oil
worn/damaged bearings which allow slight misalignment of gear teeth, resulting in whine

Note bearing problems on the pinion gear do not cause whine which disappears with power level. Thus, if bearing-related, those involved are the differential carrier side-bearings.

FWIW: I would: check fluid level; if low, top up, see if whine is affected any. If it is still present, remove differential carrier cover, inspect gear tooth surfaces for damage. If teeth bright and shiny, no scoring, pitting, discoloration, check tooth contact pattern with Prussian Blue compound. If pattern is displaced from acceptable location on tooth center, worn carrier bearings have likely allowed slight misalignment. At that point, I would yank out the 2 axles, remove the differential carrier, and replace it's 2 roller bearing assemblies.

Be aware that the above bearing-replace is not simply "throw them on, put it all together". Gear tooth backlash (clearance) and carrier bearing preload requirements must be met: that may require changing the shimming of the bearings, which establishes acceptable gear set-up parameters.

imp

 

[SgKukov]

IMP thank you very much for the detailed response!

Yes i know when i'm in over my head and shimming the gears is definitely beyond me... ive never attempted anything like it.

Once i get access to a nice heated garage i am checking and possibly changing the diff fluid... after 95k i figure it can't hurt.