Questions about my Expedition

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wavinwayne

wavinwayne

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Jan 6, 2005
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I want to change the, well, uh, I'm ashamed to say I don't know what to call it...differential fluid??? rear end grease??? I'm sure you guys know what I'm talking about, right? It's the big round "box" where the driveshaft connects to the front & the axles connect to the sides.

Anyway, since I was under the Expy changing the oil today, I took a look at the rear end & it is labeled "Use 75W140 synthetic fluid only". What is the proper way to drain & refill this fluid & what is the best fluid to use?(Motorcraft, Mobil1, Amsoil???) There is not a drain plug & I didn't see a fill hole either.

Thanks in advance.
 
Seeing how youa re out of waranty I would not even consider 140Wt. You can use a quality synthetic 70W90 or such and save some gas money!! The only exception would be if you tow a lot with it at or near the limit!!!

Depending on the rear end you will either have a large bolt on the bottom to drain and a simalar sized bolt on the rear side to fill. If you do not have this type of set up then you must remove the rear diff. cover to drain the fluid out.

The term you were searching for was "Gear Lube"! It does not matter if you know the lingo as long as people understand what you need! So do not fill sily! It is always better to come right out and say that you do not know then to try to work around it! I often ask people what a word means if I have never heard it in the context it is being used!!
 
simple: drain and refill!

If there is an upper and lower plug, open the UPPER one first! It sucks to have the fluid drained and not be able to refill.

If there is only a fill plug, youll have to take off the cover. Its not hard, you just need to be sure to get off the old gasket and make the surface VERY clean.

Id say to use SF or redline diff fluid. I dont see a reason why you couldnt use 75w-90, but I assume it has something to do with the way these diffs are built. Others will surely chime in on the safety of using 75w-90 in a ford diff. Syn oil should give you more protection one way or another.

JMH
 
no such thing as a dumb question..if the truck has independant rear suspension, it may have the large bung in the rear housing. the live rear ends ( like an 8.8inch under a fox bodied mustang ) have the differential cover that is easily removed.when the cover is removed, you can have a look at the condition of the crown and pinion gears, the spiders and case gears for pitting, lack of lube damage etc,
easiest way to install the oil back into the housing is to buy a suction gun ( looks like a tube with a hose on one end, and a pull out handle on the other)
kind of messy though..
oh, btw, dont forget to check the tag on the differential to see if you need to add friction
modifier to the gear oil

good luck
canada.gif
 
Thanks for your help, guys. I am 100% positive that there is not a drain or fill plug anywhere on the cover. I looked very intently for them & did not see either.

Even with all the great advice you all have given me, I'm still confused on how to re-fill this sucker. It looks like the cover will have to be removed to drain the fluid, but how in the world do I get the new gear lube in if there is no fill hole? And how do I know how much fluid to pour in?

Just to be on the safe side, I'm going to stick with the recommended 75w140 & just buy the Motorcraft gear lube & friction modifier(if I need it) from the Ford dealer. I'll ask one of the Ford mechanics how to do this & if they give me the run-around, I'll just pick up a Hayes manual from AutoZone. Maybe the Hayes manual will show some illustrations, since I am a little bit of a slow learner. Sorry for rambling on.
 
Wavin',

There should be a square head 3/8" fill plug on the differential case. On the Explorers, it's on the drivers side and facing forward, so you might find it there.

As far as getting the fluid into the diffy, many auto parts stores carry oil pumps that allow you to pump directly from the bottle to the diffy via a plastic hose.

You might check our GL5, MT-1 75W140 since it is equivalent to Ford's OEM fill.
 
Waven,

As Mola say the fill plug is on the drive shaft side of the diff, facing the front of the truck on the driver's side. The suction "pump" looks like a grease gun. You can use it to fill the diff. It can be bought at any auto parts store. I've even seen them at Walmart. Thy're about $14 but it'll last a lifetime. I used Mola's SF's HDS-5 75W-90. I have a 2002 F-150 that also came with Ford's 75W-140. But I don't tow so I went with the less viscous fluid in the hopes of helping the mpg a bit. If you buy the Ford diff fluid it's going to cost you a fortune. I think it's well over $20/qt
shocked.gif
. Even with the shipping Mola's will be less expensive. It's going to take almost 1 gallon to reach the fill hole. Though after I did it I read in the manual that you're supposed to fill it to about 1/2" below the fill hole. For the last 35 year's I've alway filled it to the fill hole level
dunno.gif
. A mechanic recommended using the Permatex Ultra Blue RTV silicone. Just make sure you do a real good job of cleaning all old gasket material off the diff cover and the diff itself.
Whimsey
 
The Ford rear ends do not have a gasket, you have to use the RTV like Whimsey suggested. Stuff ain't cheap, but will probably be the last time you'll have to fill it, so get the good stuff. One thing you need to check into and I've been meaning to ask this of Mola as well. Check to see if your rear is Limited Slip. You may have to add a friction modifyier to it. Don't know if you have to if using Mola's product.
Mola?????? what sayeth thou?????
 
Thanks a ton, fellows! I found the fill hole!
smile.gif
It's right where you guys said it would be. The only difference is that it is a socket set screw instead of a square head screw.

A couple more questions:

1. If I'm not supposed to fill it all the way to the fill hole, how do I know what the level is?

2. If I do need FM, when do I add it to the diff., before or after filling with gear lube?

So, just to review; I have to take the cover off to drain, since there is not a drain hole. Next, I scrape all the old gasket material off & add blue RTV silicone to the mounting interface as my gasket. Lastly, I simply re-fill to the proper level with new gear lube & FM (if needed). Does this sound right?
 
Scrape anything on the pumpkin and differential down to bare metal. Again, Ford does not use a gasket. The FM is only if you have limited slip. I'm kind of thinking you don't, but check the owners manual or look up the VIN. There is a gasket for it made by a company other than Ford.
 
How do I know if my Expedition has a limited slip rear end? There is no indication on the axle or on the diff. cover.

Thanks in advance.
 
http://www.fcsdchemicalsandlubricants.com/supplier/quickref/axlelube.pdf

Can one of you gurus please help me interpret the above axle lube chart? Look at the fluid refill amounts listed. They are shown in PINTS. If I'm reading this right, my '97 Expedition only needs 3.5 PINTS of synthetic rear axle lubricant & .25 PINTS of friction modifier.

I have read several posts, on BITOG & elsewhere, where people have stated that their Expeditions & F-150's needed close to 4 QUARTS (not PINTS) of axle lubricant.

Please help me; I'm determined to do this myself, but right now, I can't figure this out.
 
If you use a lubricant that NORMALLY does not require the addition of LS additive, then you should not have a problem or concern. Some of those were mentioned above in earlier posts.

I think your vehicle takes 5.5 pints of gear oil. So one of your options is to buy 5 quarts with the understanding that you can take the other two back if not needed. Save the receipt. If you mail order fluid, only buy 3 quarts.
JMO

dunno.gif
 
quote:
Originally posted by wavinwayne:
How do I know if my Expedition has a limited slip rear end? There is no indication on the axle or on the diff. cover.

Thanks in advance.
Click to expand...
You should have a metal tag held onto the diff cover. It tells you the rear end you have 8.8 or 9.75 and if you have a limited slip it'll have an L after your gear ratio of either3.31, 3.55 or 3.73. If you don't have that tag then your rear diff fluid was changed at least once and they lost the metal tag. You can check on the driver's door jam or the door itself. It'll have a sticker with various info in codes on it. There is a code for the axle, if it has an H in it then it's a limited slip axle. Either rear diff takes 5.5 pints according to the owner's manual. Many synthetic diff fluids, other than Ford's, already have a friction modifier in it. But if you find you need "more" you can easily buy it at the dealer or even Advance Auto has it. As I said I filled mine till it was level with the fill hole and it took almost 1 gallon. So far It's not puked out the vent so filling till it was level with the fill hole was fine. Plus you have extra fluid to provide better lubrication and absorb more heat. All around it's better for the gears. If you have a 4X4 don't forget the front diff, which takes 75W-90, 2.0 Liters, just short 2 quarts, but you can top it off with the rear diff fluid left from the gallon, even if it's 75W-140. As a bonus the front diff has a DRAIN and fill plug. The transfer case uses 2.0 quarts of ATF, and also has drain and fill plugs. I would recommend SF's GL-4's replacement fluid for ATF viscosity fluid in a transmission or transfer case. Or at the very least a synthetic Mercon ATF.

Contact Mola at Specialty Formulations and he can advise you best. I have their transmission and gear oil in my truck and will soon add it to the wife's Explorer and my Contour.

Plus as an added bonus ordering a gallon saves you money over ordering 4 quarts when you order from SF
grin.gif
.

If you have any questions feel free to e-mail/pm me.

Whimsey
 
Hey Wavinwayne,
Here's the deal on servicing your differential.
1. Remove the inspection cover. 13 mm bolts. I usually use a putty knife with a few gentle taps from a hammer to break the silicon seal. Clean off all silicon. Brake clean and a razor blade usually work best. At the bottom of the diff. housing there is a little bit of fluid (usually a little extra fluid with metal particles in there) go ahead and scope it out as best you can. Assemble inspection housing. I use Motorcraft Gray silicon (thats what we use at our Ford Dealer).
2. Now the good part, filing the diff. I remove the fill plug with a short 3/8 extension and out it is. Next remove the speed sensor on top of the diff. Probably a 10 mm socket to take the bolt off and wiggle the sensor off. That is where I fill it until it comes out the fill hole (the Motorcraft quart gear lube with the nipple that come on the bottle fits perfectly on there). Reinstall, roadtest, reinspect oil level and you are done.
At our dealer 140W synthetic oil is $29 a quart and if you would like to remove the tags off the diff first the parts dept. can tell you if you need a friction modifier (you probably will).
Over and out,
Clutcher
 
How do I know if my Expedition has a limited slip rear end? There is no indication on the axle or on the diff. cover.

Thanks in advance.
_________________________________________________


Maybe someone else knows if this is still a way of checking but I know on the older vehicles if you raise both rear wheels and rotate one of them and if the other one rotates the same way then it is a limited slip if it rotates the opposite way then it is not.

Does anyone know if that works for the newer vehicles?
 
Just out of curiosity, what would happen if I added friction modifier to a differential that didn't require it?
 
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