Differential service question

[scjmc]

I need to change the oil in my differential (125K). I found in the FSM that it takes 1.4 liters, or 3 pints of synthetic 75w-140. I also read that you are supposed to fill it to 1/8 to 3/16 of an inch below the fill plug. My question is this where is the fill plug at? I looked at a parts diagram and cant locate the fill plug. I also need to know if the old fluid has to be pumped out or if there is a drain. I took a quick look under the car and didnt see a fill plug or drain. Thanks......

 

[fastmark1993]

Iirc it's on the right side of the diff and it needs to be pumped out. Use a 3/8 ratchet to get the plug out

 

[scjmc]

Thanks for the info, I will look on that side and get a pump.

 

[fastmark1993]

No prob, dun need a pump just a suction gun with a hose that'll cram down the fill tube

 

[nelliott500]

Sorry to drag this back up, but I figured it would be better than making a new thread.

Wouldn't it be better to take off the differential cover to get all of the fluid out instead of trying to suck it all out? With my Camaro, I just cracked the cover open, let as much fluid drain out as possible, and then pulled the cover off to clean it up.

If I pull the cover, is there a gasket or do I just use some RTV red to seal it up?

What about gear oil? Go with Motorcraft from the dealer or step up to Royal Purple?

 

[joegr]

Sorry to drag this back up, but I figured it would be better than making a new thread.

Wouldn't it be better to take off the differential cover to get all of the fluid out instead of trying to suck it all out? ...

Yes, it would be better, but it's not too practical. As I recall, the differential is mounted by the cover, so I think that you have to drop it to do that.

 

[nelliott500]

Well, I did order a suction gun for when I change out the trans fluid and filter. It looks like fastmark1993 recommends something like that for the job so I guess that should work.

The entire reason I asked is because my service manual doesn't have any info on replacing the fluid in the differential.

 

[nelliott500]

Well, I went with 75W-140 right from the Ford part's department. Same with the trans fluid. Figured I should probably just use what the dealer specifically recommends.

What about the additive for the differential? I didn't get it because I wasn't sure if I needed it.

 

[oddball]

Wouldn't it be better to take off the differential cover to get all of the fluid out instead of trying to suck it all out?

Heh. Funny story. I bought a bunch of diff fluid (that is pricey stuff!), did normal maintenance then propped up the back of the car.

Hard stop. That cover ain't coming off.

Take a look a few days before doing the job so you know what you're up against. Lesson learned for me - never assume one method that worked on another car (or many cars) will work on any other car.

 

[nelliott500]

What stopped you? Just couldn't get it to come loose? I remember having to pry at it a bit to get it started on my Camaro.

The hand pump is already coming and, since I'm not doing the trans fluid myself now, it will be nice and clean to suck the gear oil out of the diff.

 

[joegr]

What stopped you? Just couldn't get it to come loose? I remember having to pry at it a bit to get it started on my Camaro...

I think that we're being too subtle here. It's not like most cars, and it's not a matter of being stuck. You need to look at yours and you will see.

Most differentials mount to the car via the front housing. This one mounts by the rear cover. If you don't mind dropping the exhaust and the differential, then you can certainly do it.

 

[nelliott500]

I think that we're being too subtle here. It's not like most cars, and it's not a matter of being stuck. You need to look at yours and you will see.

Most differentials mount to the car via the front housing. This one mounts by the rear cover. If you don't mind dropping the exhaust and the differential, then you can certainly do it.

Well that's the answer I was looking for. :lol: I haven't looked at the differential yet. I plan to tackle that this weekend. I've only had the car for a week. I haven't learned all the ins-and-outs yet.

What about the friction modifier additive? Necessary for the differential fluid?