I am planning on changing the differential oil in my 2000 expedtion. Where Do I refill at? Can I take the sensor out and refill through there?
Also have heard differring opinions on using Gasket or silicone. I am pretty sure my Auto Zone has the gasket and perhaps easier than the several stage process of hand tightening the bolt until it oozes out and then letting it sit. But I know my repair shop that wanted $175 said to use silicone.

 

Front diff? Use Permatex Black for the gasket. There is a fill hole once you've popped the cover off and reset it. Rear diff should be both drain and fill holes. Always make sure you can get the fill port open before you drain.

 

I am doing the rear. So the fill port is a plug not a screw in?

 

Not sure about your front diff, but I am pretty sure with the rear, you will need to pull the cover to drain the fluid out, as there is no drain plug. To fill, there is a plug on the front of the housing, driver's side. That is how my 2002 is. I think the rear axles were the same for all Expeditions up through 2003, when they went to an IRS setup.

 

it screws in.you use a ratchet without a socket...

 

Sorry, my mistake on the rear. You should still make sure you can get the fill off, probably easier while still on the car. Permatex is a good gasket. If you have a LSD make sure to use the correct fluid and add the friction modifier.

 

You didn't state which engine you have, but I believe there were two different rear ends used - the 8.8" and the 9.75", depending on engine application.

I found it difficult to find a rear cover gasket for the 9.75 - the parts guy would always bring out the 8.8" gasket. If you are patient and clean the mating surfaces without scratching them and wipe the surfaces down with brake clean, the black silicone will work on either diff. (Both diffs have a fill plug on the DS near where the driveshaft connects to the pinion shaft, as others have stated.)

If you plan on following Ford's specs the rear diff uses a High Performance Full Synthetic gear oil with a 75W-140 rating. Additionally, if you have the Limited Slip diff you may have to add 4 oz of a Friction Modifier to keep the clutches from chattering.)

Refill capacity is between 5.5 and 5.8 pints, depending on which rear end you have. Note that when you refill the diff Ford specs are 1/4" to 9/16" BELOW the bottom of the filler hole.

Before you add that nice new gear oil, you might want to check your rear axle seals to be sure they are not starting to leak. If they end up having to be changed, you don't want to have to drain the rear diff again just to change them.

 

how can i tell if i was lucky enough to have a lsd

 

Look at the sticker on the inside of your driver's door. Where it shows your axle code, if you have the LSD, the letter 'H' will appear in front of the number. H9 is a 3.55 LSD. Not sure off the top of my head what the 3.73 was - possibly 7?

 

sweet i have the 3.55 lsd.

 

Thanks for all the help. I did not have the LSD and everything is back together. Just praying for no leaks. Based on what the packaging from Permatex I resisted not really cranking down on the covere bolts. I guess this would damage the permatex seal?

 

Glad everything went well with your fluid change. Too much torque on the bolts will squish the Permatex out before it has a chance to set and dry - better chance of an area for the fluid to sneak through. Good luck & hope there are no puddles under your rear axle in the morning.