Changing differential lubricant

[ma96782]

Some.............syn diff oils.............say, it isn't needed.

Up to you who you wanna believe.

Aloha, Mark

 

[gijoecam]

Like they said. Before you remove the cover, take a wire brush around the outside lip to loosen up the dirt and rust. Then blow it clean. When you remove the cover, remove all of the bolts but the top two. Carefully pry the bottom away. This will let it drain out without dumping - Get a large drain pan if you don't have one. Once you hav everything apart, tuck a rag in the pumpkin over the gears to prevent dirt from falling. Wipe the gasket surface with brake cleaner. Remove the rag. Clean the cover and then apply rtv around the edge. Carefully place it back on the pumpkin and bolt it up, tightening in a cross sequence (like a tire). Remove the drain plug with a 3/8" ratchet. Clean it with a blow gun to remove the metal filings (it's got a magnet crimped into it). Fill the differential until it drips out the hole. Apply a little rtv to the threads and replace the plug. Good luck

Ditto. I'd mirror everything he said, except I'd remove the fill plug FIRST. There's nothing worse than getting it drained, cleaning it, sealing everything back up, and then discovering that you can't get the fill plug out. (been there, done that, got the t-shirt LOL!!)

-Joe

 

[Homerexplorer]

Ditto. I'd mirror everything he said, except I'd remove the fill plug FIRST. There's nothing worse than getting it drained, cleaning it, sealing everything back up, and then discovering that you can't get the fill plug out. (been there, done that, got the t-shirt LOL!!)

I completely agree. I guess I didn't think about that because I've done it a couple of times so it's pretty easy to get off. I'll probably change the way I do it in the future - just to be safe.

 

[gijoecam]

Yeah, I learned that the hard way once on an older Ranger I had.... Had something similar happen a couple months ago when changing the oil too: Pulled it up on ramps, drained it, changed the filter, then realized the hood wouldn't release when I pulled the handle. The latch is sticking on me for some reason, so I've gotten in the habit of popping the hood every time I fill up.

-Joe

 

[scaperrotta06]

The diff change was really easy i dont know why i was gonna pay for it. the only problem i had was the pump i bought only fit over the gallon bottles so with a juice jug and alittle tape it worked lol i put 2 oz of lsd additive per quart i hope thats not to much and the shop wanted to do it for $150 haha

 

[masospaghetti]

Did my differential this afternoon thanks for the help everyone.

The plug on mine was relatively easy to get off. I opted also to use a pump to drain the differential instead of pulling off the back cover. I put in about 2.5 quarts of 75w-90 and it seems almost full (I ran out, didnt think it would take so much).

Worked great, slid a 7/16" heater hose into the filler hole, it was a tight fit but it went all the way down and the pump yanked everything out. A whole bottle of greasy nastyness.

 

[scaperrotta06]

really only 2.5 i put 3 quarts of mobil 1 and 5oz of lsd additive and it ate it all up and i was wondering if that was enuff lol

 

[masospaghetti]

hmmm maybe I need to add more then, It didn't seem like 3+ quarts came out of there to begin with...and I thought someone had said it took 5.5 about 5.5 pints?

 

[kythri]

It kind of depends... do you have a limited slip? if so, you shouldn't use the 75w90, book calls for 75w140 w/ friction modifier. If you have an open diff, you're using a non-specified lubricant (the 75w140), and have no need for the friction modifier, a waste of money, IMO.

I fought this same battle in my head (I have a open diff) I went with 75w90 Mobil1. (after 2 trips to the store)

With the LS, which book calls for 75W/140?

I can't find it now, but I thought I just read that it was supposed to use 80W/90 with the friction modifier.

 

[gijoecam]

With the LS, which book calls for 75W/140?

I can't find it now, but I thought I just read that it was supposed to use 80W/90 with the friction modifier.

See your owner's manual, page 249. Open rears use 80W90. 4.0 OHV, 4.0 SOHC, or 5.0 and with a 3.73 or 4.10 rear ratio calls for synthetic 75W-140.

-Joe

 

[Fredness]

Since 1998, Ford has been doing this "Sealed-For-Life" thing where they use synthetic fluid in the rear and manual transmissions. There is no recommended change interval, but I'm doing it soon since I think 80K is plenty. Going Amsoil....

 

[daffy]

diff lube change

I let mine go for 117k before changing, I thought that was too long.

 

[302Xplorer]

No new gasket is needed? Just the RTV?

 

[ma96782]

Sorry double post.

Aloha, Mark

 

[daffy]

No new gasket is needed? Just the RTV?

Black RTV, I don't think they even make a gasket

 

[kythri]

OK, I need some help here.

I'm in the process of converting (or getting ready to convert, as it were) my '99 XLT to full synthetic - Front Differential, Rear Differential, Transfer Case, Transmission, Oil, etc.

I've gone out and picked up just about everything I've needed, save for the 75W140 for the rear diff, and I'm waiting on my Fumoto Valve to do the oil.

I picked up 3 bottles (3 liters or so) of Mobil1 Synthetic 75W90 to put in the front differential, and decided that I was going to tackle that tonight.

I've read everything I can find on here, and in both my Haynes and Chiltons books on changing the fluid in the front diff, and how it has to be suctioned out through the fill hole.

I had myself all ready to do this, with some bottles to put the old fluid into, and I got underneath my truck to do this.

The only easy part was popping out the fill plug.

I don't know what I'm doing wrong, but I can't seem to get a hose in there suck anything out.

I ended up getting out approximately a whopping 2 ounces of old fluid, and couldn't get anything else out.

What's the trick to this? The reading on this makes everything sound nice and easy - pop the hose in, suck the old stuff out (approximately 1.5-2.0 liters), and pump new stuff in.

At least on my truck, it ain't that easy.

I'm at the point now where I'm wondering if it might be easier to pull the whole differential out and pop the cover to drain.

Help! Please!

 

[ma96782]

Are you sure the hose is hitting the bottom of the case?? I mean...maybe the hose isn't all the way at the bottom (hitting the gears).....and thus the explaination for the low volume of old lube?

Aloha, Mark

 

[kythri]

Hrmm...

The first couple attempts at putting the hose in there, it definitely tagged the gears, but on several other attempts, I was able to get it in smoothly - perhaps it's just wrapping around, semi-horizontally...

At this point, I'm thinking I may just take my fluid to a Jiffy Lube or Oil Can Henry's, have them evacuate what's in there, and put in my new stuff...

 

[rbejexp]

I am curious on the cost of the Motorcraft 75W140 Synthetic, I can't find it anywhere. I know Mobile 1 is about $17 for a one liter bottle (autozone). There is a local guy that is sell a couple of complete kits to perform a change of differential fluids along with a RTV sealer and friction modifier. He is offering Motorcraft 75W140 (4 quarts) Friction mod., and RTV Gasket, all for $30.00. Does this sound like a good deal? He mentioned he was an ex Ford service guy, sounds all legit.

 

[itsbigtiger]

my front differential is leaking from the bottom of the front cover.does jiffy lube seal that when you change the front diff fluid?

1999 Ford Exlorer xlt