Changing Diff Fluid

inferno9898

Member
May 17, 2003
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None of the local auto parts stores stock differential cover gaskets...can I just use form-a-gasket? Neither the shop manual or bullittarchive mentions a gasket, but it is listed as a part, so i figured i'd at least look for it.
 
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No need to use one. Get some black RTV gasket maker and use that. Also make sure you put a small bead all the way around covering the bolt holes. I went throught the same thing with the gasket and places not having it so I called Ford and they told me to use RTV, so I did and it worked fine. Hope that helps.
 
Thanks for the post DT.

Since my original post and now, my dad has gone and picked up a little drill pump connects to a hand drill. I figure it would be easier to just suck the oil out rather than remove the diff. cover. I'm switching to Royal Purple synthetic...think there will be any problem with the pump not being able to suck all of the fluid out? I'd imagine it can get most of it.
 
Honestly, It is going to be pretty difficult to get all the fluid out with just a pump. I had a hand pump and could barely get any out compared to what came out when I pulled the cover. I recommend draining it by loosening all the bolts except for the top 2 or 3 and let it all drain out. Remove cover, scrape old RTV off, with a lint free rag wipe the rest of the fluid out of the differential, inspect your teeth on your gears, clean the inside of the cover with parts cleaner (spray), re-RTV the cover flange and bolt it back up. Then fill.

It is messy and takes more time but you can be sure it is done right. Just my opinion. :)
 
Doing mine was a big pain in the ass, tryin to get the diff. cover through the rear sway bar was a hard and it was indeed very messy, have fun. I used RTV and a gasket when i did mine.
 
dude its easily a half hour job even for a first timer.

1) loosen all 10 bolts. then remove the lower 8 leaving the 2 top ones still in, but loose.

2) stick a fluid catching bucket under the diff. then with a flathead, pry the bottom of the diff cover from the housing. you can do a little bit to where it just starts to seep out, to keep things clean. or you can just pry that mofo all the way and let the fluid splash you. your choice.

3) remove top bolts and diff cover. stick your hand in the diff and make sure all the fluid at the bottom comes out as well. if your rear is jacked up, youll have a little puddle in the housing, make sure to get that **** out of there.

4) clean diff cover with a rag, and scrape off the old gasket material as best as possible. then come over to the diff, and scrape off that material as well. the surfaces need to be as clean as possible.

5) apply a generous bead of RTV Black over the mating surface of the whole diff. make sure to get around the bolt holes as well, but bead them on the inside part of the hole. you want to seal the bolt hole from the diff, or else the fluid will leak through the bolt holes if you put the bead on the outer side of the hole.

6) reattach rear housing and bolt down. use german torque method (guut en teit) if you dont have a torque wrench and specs nearby. usually youll know, since all the RTV will start to compress and seep out the sides.

7) i like to let my gasket making material sit for a while to set up before letting fluids possibly ruining it.

8) now get out your bottles of rear fluid. i used Royal Purple 75w90. i had some tubing laying around, that i stuck on the tip of the nozzle of the bottle that fit perfect.

9) now go under the car. remove the filler plug behind the differential housing. its located on the drivers side towards the front of the car(opposite of the rear housing you removed). use a 1/2" drive and a 2-3" extension to get that sucker off.

10) if you had a hose laying around, this part is easy. stick the end of the hose in the fill hole a good 2" inside. then bring the bottle up in the chassis as high as you can get it, usually next to the fuel tank. theres a ****load of room up there. then just squeeze the bottle until it is empty and repeat. 2 bottles is all you need. actually if your rear is jacked up, you might get 1.85 bottles in, due to the slope the rear will be at in relation to the fill plug. this is perfectly fine.

11) reattach drain plug using german torque method and youre done.

12) i drive the car for a good half hour. then bring it home and let it sit and check for leaks from the RTV. if you applied a good bead and let it setup, you should be fine. i was.
 
By no means is it a half hour job for a first timer in the home garage...however it is not difficult if you just take your time. I also let the RTV set for an hour before I put the new fluid in...but I take my time. Just don't want you to think it will be that quick. Get ready for some nasty stinky fluid, too. Anything you get it on will smell that way for a long time.
 
SigmaPride said:
By no means is it a half hour job for a first timer in the home garage...however it is not difficult if you just take your time. I also let the RTV set for an hour before I put the new fluid in...but I take my time. Just don't want you to think it will be that quick. Get ready for some nasty stinky fluid, too. Anything you get it on will smell that way for a long time.
Yeah, it def. wasn't a 1/2 hour job for me. Without a lift or the car significantly jacked up its a bitch doing this type of job under the car and the gl-5 smell or any other gear smell reaks to high hell.:nice:
 
Tally_4.6 said:
Yeah, it def. wasn't a 1/2 hour job for me. Without a lift or the car significantly jacked up its a bitch doing this type of job under the car and the gl-5 smell or any other gear smell reaks to high hell.:nice:
I agree Tally changing the differential oil is so, much easier
if you have a lift.My mechanic and I changed mine in a 1/2 hour
and I even used Royal Purple to boot. :D
 
1. jack up car 2min
2. remove cover and drain 5-10min
3. replace cover 10min tops
4. fill back up 10min

this is literal a fast job the only way it could take a long time is if you just did not have what you needed. if you have a jack, jackstands, a 3/8's rachet, extention, the 12 or 13mm socket for the cover bolts, rtv, and the fluid there is no reason you could not be driving the car out of the garage in 30-40min.

just use rtv for the cover. I use black because it is the same color as the rear and there is nothing real high temp about the rear cover.