I searched, searched and searched some more. What I found is. This is a known problem by Ford I wish I would have known about before I bought this year'd Explorer. Oh well, only because I really like the truck and own it now. I have to fix-it.
I drained the rear-end oil yestarday and it was a silverish-grey. I believe telling me a bearing failure. I searched for others who ran into the rear-end problem with their Explorers looking for their fixes. I didn't find any updated fix. I did find this post which is a few years old:
quote
1.fficeffice" /><O></O>
<TABLE style="BORDER-RIGHT: 2.25pt outset; BORDER-TOP: 2.25pt outset; BORDER-LEFT: 2.25pt outset; WIDTH: 96%; BORDER-BOTTOM: 2.25pt outset; mso-cellspacing: 0in; mso-padding-alt: 2.25pt 2.25pt 2.25pt 2.25pt" cellSpacing=0 cellPadding=0 width="96%" border=1><TBODY><TR><TD style="BORDER-RIGHT: #ece9d8; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; BACKGROUND: white; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 25%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: #ece9d8" vAlign=top width="25%">TSB

05-23-3 <O></O>





</TD><TD style="BORDER-RIGHT: #ece9d8; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; BACKGROUND: white; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 65%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: #ece9d8" vAlign=top width="65%">

• REAR AXLE NOISE REPAIR <O></O>

</TD></TR><TR><TD style="BORDER-RIGHT: #ece9d8; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; BACKGROUND: blue; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; PADDING-TOP: 2.25pt; BORDER-BOTTOM: #ece9d8" vAlign=top colSpan=2>Publication Date: November 4, 2005 <O></O>



</TD></TR></TBODY></TABLE>
<O></O>

FORD: 1997-2005 Expedition, F-150
2002-2005 Explorer
LINCOLN: 1998-2005 Navigator
2003-2005 Aviator
MERCURY: 2002-2005 Mountaineer

This article supersedes TSB 05-12-6 to update the Service Kit and Service Procedure information.

ISSUE:
Some vehicles may exhibit an axle whine or hum during acceleration, deceleration and/or cruise.

ACTION:
An axle repair kit has been developed which incorporates most parts required for a comprehensive axle repair. The kit should be used instead of installing a complete axle assembly to repair an axle whine/hum. Replace Ring and Pinion with Axle Kit and Components.

NOTE: REFER TO THE "DIFFERENTIAL RING AND PINION" IN-VEHICLE REPAIR PROCEDURE IN THE ONLINE WORKSHOP MANUAL SECTION 205-00, FOR THE LATEST AXLE DIAGNOSIS AND REPAIR PROCEDURES.

NOTE: FOR 1999 AND PRIOR MODEL YEAR VEHICLES, USE THE 2000 MODEL YEAR WORKSHOP MANUAL.

NOTE: WHEN SERVICING THE REAR AXLE ON ANY 2002-2004 F-150, EXPEDITION, NAVIGATOR, EXPLORER OR MOUNTAINEER BUILT BEFORE 3/30/2004, IF FLUID REPLACEMENT IS REQUIRED, REPLACE THE ORIGINAL FUEL EFFICIENT HIGH PERFORMANCE (FEHP) SAE 75W-90 REAR AXLE LUBRICANT WITH SAE 75W-140 HIGH PERFORMANCE SYNTHETIC REAR AXLE LUBRICANT. WHEN THE FLUID TYPE IS CHANGED, REPLACE THE CURRENT "FEHP" METAL TAG WITH A NEW "75W-140" TAG (F3TZ-4121-AA). IN ADDITION, REMOVE OR BLOCK-OUT THE FEHP REFERENCE ON THE MULTI-COLORED LABEL LOCATED ON THE RIGHT SIDE AXLE TUBE. IF THE AXLE IS A LIMITED-SLIP MODEL, USE XL3 ADDITIVE FRICTION MODIFIER IN THE QUANTITY RECOMMENDED BY THE WORKSHOP MANUAL.

KIT ORDERING: REFER TO THE VEHICLE AXLE TAG FOR AXLE RATIO IDENTIFICATION

5L3Z-4209-A = (8.8-Inch Ring Gear/3.31 ratio) (1997-2005 F-150)
5L3Z-4209-B = (8.8-Inch Ring Gear/3.55 ratio) (1997-2005 F-150, 2002-2005 Explorer/Mountaineer/Aviator)
5L3Z-4209-C = (8.8-Inch Ring Gear/3.73 ratio) (1997-2005 F-150, 2002-2005 Explorer/Mountaineer/Aviator, 2003-2004 Expedition/Navigator)
5L3Z-4209-D = (9.75-Inch Ring Gear/3.31 ratio) (1997-2005 F-150, 2005 Expedition/Navigator, 1997-2002 Expedition/Navigator)
5L3Z-4209-E = (9.75-Inch Ring Gear/3.55 ratio) (1997-2005 F-150, 1997-2002 Expedition/Navigator)
5L3Z-4209-F = (9.75-Inch Ring Gear/3.73 ratio) (1997-2005 F-150, 1997-2005 Expedition/Navigator)
NOTE: 9.75 REAR AXLE HOUSINGS WERE REDESIGNED IN MID-1999, INCREASING FRONT PINION BEARING SIZE. REPLACING RING & PINIONS IN AN OLD-STYLE AXLE ASSEMBLY WILL REQUIRE INSTALLATION OF SPACER P/N YL3Z-4662-CA. SPACER IS TO BE INSTALLED BETWEEN INNER PINION BEARING AND COLLAPSIBLE SPACER.

THE AXLE SERVICE KITS INCLUDE THE FOLLOWING COMPONENTS:

4630 - Head Bearing
4628 - Head Bearing Cup
4676 - Pinion Seal
386989-S2 - Washer (Slinger)
4621 - Tail Bearing
4616 - Tail Bearing Cup
4222 - Differential Bearing Cups
4221 - Differential Bearings
4209 - Gear Set (includes pinion shims, pinion nut and crush spacer)
4209 - Instruction Sheet
NOTE: THE KIT DOES NOT INCLUDE THE FOLLOWING ITEMS. SOME OR ALL OF THESE ITEMS WILL BE REQUIRED TO COMPLETE THE AXLE SERVICE, DEPENDING ON AXLE APPLICATION/STYLE.

ORDER AS NEEDED:

NOTE: REUSE OF RING GEAR BOLTS, CARRIER BEARING CAP BOLTS AND DIFFERENTIAL SLAVE PIN RETAINING BOLT REQUIRES CLEANING OF THREADS AND INSTALLATION OF TA-27 STUD AND BEARING MOUNT RETAINING COMPOUND & SEALANT.

YL3Z-4662-CA - Pinion Bearing Spacer for 1997-1998 9.75 axles
XG-14 - Gear Marking Compound
4067 - Differential Shims 0.241" to 0.307"
SAE XY-75W140-QL - High Performance Synthetic Rear Axle Lubricant
XL-3 - Additive Friction Modifier (Limited Slip Axles Only)
205-506 - Seal Protectors (Rotunda Tool)
W710084-S439 - Wheel End Nuts
390266-S100 - Differential Slave Pin Bolt (9.75" axles)
387426-S100 - Differential Slave Pin Bolt (8.8" axles)
4B422 - Axle Circlips
ZC-21 - Metal Surface Cleaner
TA-29 - Ultra Silicone Sealant
TA-27 - Stud and Bearing Mount Retaining Compound and Sealer
F3TZ-4121-AA - Fluid Tag (REQUIRED IF FLUID TYPE IS CHANGED FROM FEHP DURING REPAIR)

WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage

OPERATION DESCRIPTION TIME
052303A 1997-2002 Expedition, 1998-2002 Navigator, 1997-2004 F-150 Heritage, 2004-2005 F-150: Rear Axle Noise Repair (Includes Time For Road Test To Verify Concern (Beam Axle)) (Do Not Use With 4205A Or 4205A4) 4.7 Hrs.
052303A 2003-2005 Expedition: Rear Axle Noise Repair (Includes Time For Road Test To Verify Concern (Irs Axle)) (Do Not Use With 4010D Or 4010D4) 5.8 Hrs.
052303A 2003-2005 Expedition/Navigator With Air Suspension: Rear Axle Noise Repair (Includes Time For Road Test To Verify Concern (Irs Axle)) (Do Not Use With 4010D Or 4010D4) 5.9 Hrs.
052303A 2002-2005 Explorer/Mountaineer, 2003-2005 Aviator: Rear Axle Noise Repair (Includes Time For Road Test To Verify Concern (Irs Axle)) (Do Not Use With 4010D Or 4010D4) 6.6 Hrs.

DEALER CODING
BASIC PART NO. CONDITION CODE
4209 14
unquote

Can anyone tell me if there's an updated TSB or an updated fix?

Or the inscript in RED is it.
Thanks,

 

i had this problem. did not appear to be bearing related since you can back off on the throttle and it goes away.. i thought it must be gear mesh. .. i drained the oil, and it was silver. cleaned out and added the thicker FUL SYNTHETIC 75s 140 and added the 7 oz of friction modifier. About 75% of the noise went away and i am happy.. Some have not had this luck, but i dont hear a bearing noise, it was just gear whine. THE full synthetic is "sticky" and i beleive it hangs on the teeth better. the friction modifier does something, but i sure cant explain it.. it worked.

 

I've read your post and tried doing what you suggest(a small cost for diagnosing). Unfortunately, my problem is much more severe than yours. Yes, the vibration/noise lessons when I back off the throttle and even if I shift to nuetral at 60+. But, the greyish/silver tint to the oil is small particles of either gears or bearings. BAD. BAD. If I it were a prob with gear mesh you would get a whining when decelarating. Ecspecially at low speeds.
I am hoping someone has seen the TSB I posted and will be able to help me with an updated fix.

Thanks,

 

did you figure this out

thanks wayne