I've already changed the transfer case ATF and now I need to change the front and rear differential fluid (I have a 4x4). I bought 6 quarts of Mobil 1 75W-90 synthetic gear oil. According to the manual, that should cover it. I also bought a hand operated transfer pump to pump out the fluid.

My question is, (I haven't looked yet) is the plug on the differentials just like the plug on the transfer case? I mean, can you stick the end of a 3/8" extension into it to get it out?

Do you simply fill it to the bottom of the fill plug so it almost starts to run out/overflow out the plug?

Any tips or things to know?

 

Good morning!

That fluid is fine fer the front, but NOT the rear. For the rear you need 75w-140 full synth, and also 4 oz of MC XL-3 supplement (rear Traction Lok)

The owner's manual gives complete details on the change. There is no plug on the rear - you need to crack to drain /remove the cover.

You can download/view the manual here: http://www.motorcraftservice.com/vdi...&menuIndex1=17

You can use a small squeeze bottle and a length of tubing to add fluid if you find it kinda tight.

Good luck!


MGD v4.1

 

Oh.....crap. I was just going off what my owner's manual said and it said 75w-90 for front and rear...plus the friction modifier for the rear (which I overlooked until just now). The manual actually says...

"Your vehicle’s rear axle is filled with a synthetic rear axle lubricant and
is considered lubricated for life. These lubricants do not need to be
checked or changed unless a leak is suspected, service is required or the
axle assembly has been submerged in water. The axle lubricant should
be changed any time the rear axle has been submerged in water."

So...should I even bother with the rear right now? I drive all on-road, mostly highway and I see no leaks.

The clutch pack and fluid was changed on my rear end the first year I had the truck under warranty since it was binding up around corners.

I'm inclined to change the fluid, but if there really is no plug to access the fluid on the rear, I'm less inclined to want to do it for fear of creating a leak in the seal.

 

Ok I just looked under the truck. There is indeed a fill plug on the driver's side in plain view so it can be sucked out/drained from there.

Question. Why does the owner's manual specify 75w-90 and you're saying 75w-140? I can't look at that doc you gave a link to. I guess you have to have a login.

 

I changed mine around 100k because it was leaking, otherwise i wouldn't of bothered of having it done

 

Is there a gasket needed when you crack open the rear end?

 

Must be something to do with the year of the truck. My '06's owners manual shows two different fluids for the front and rear.

 

Hello!

Yer right - I just checked the '04 manual ( try this link - browse to 'Owner Guides') ==> http://www.motorcraftservice.com/vdi...ageid=&gutsid=

Very sorry about that, sir/ I have an '06, but the 9.74 LS diffs hsve not changed ... and the fluids may have improved some since then ... ( *** Callin' Labnerd, lol! ***)

I think it's due to this 75w-90 being the spec at the time, and it's since been superceded. I dunno whether either the 75w-140 or the XL-3 was available for thr 2004 MY trucks. Since you already have the lube - just go ahead. BUT - also use XL-3, okay?

As for draining - yes of course there is a Fill hole, but you won't be able to get all of the old crap out that way, nor clean the chit from inside or on the cover. Best to remove the cover - gives you a chance to look inside too - could be a good thing, lol. It's not that onerous.

Intervals - most folks are in the 'Severe Service' category whether the know, or admit it, or not - for the price & the effort, it's worth changing.

Strictly For myself - I do not believe in lifetime lubes nor 100K spark plugs, nor lifetime non-greasable suspension components, nor any other TCO Fleet crap that Ford (or any other manufacturer) pushes. Sorry - just me. Not forcing yer hand here, okay? Just. Me. Only.

You will have to Google TCO or Search for it here for further elaboration.


MGD v4.1

 

Yes, some use RTV to make a gasket, or go to NAPA and buy a gasket, or check these lubelocker gaskets out.

I used a FelPro from napa on the truck and a lubelocker on the Mustang. I tend to booger gaskets and glue my fingers together with rtv. The lubelocker is great because it's reusable.

I'm with MGD on the 100,000 mile stuff, although my truck did sit in flood water for a day or so I didn't the fluid for almost two years. The fluid that came out was fine, main reason I did the change on the truck was due to a leak. The Mustang got the change after the gear break in was complete.

 

I found a TSB related to the fluid type in the older models. I guess these days they put the thicker stuff in:

TSB 05-23-3

11/28/05

REAR AXLE
NOISE REPAIR
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)

 

Good work, Detective!

Thanks buddy!


MGD v4.1

 

The way I understand it, the TSB for this one means you might have this problem but you might not too. If the customer came in with the complaint mentioned in this TSB then they'd switch to the thicker fluid. I'll see if I can find the thicker stuff in the local stores.

 

I've not changed the differential lubricant in my 47 years of driving and I haven't had any problems. When it says "Your vehicle’s rear axle is filled with a synthetic rear axle lubricant and is considered lubricated for life. These lubricants do not need to be
checked or changed unless a leak is suspected", I take them at their word.

 

there is no stock gasket, but yes as stated above use RTV to seal it

 

So what fluild did the 2004s come with from the factory? 75w140 of 75w90?