While re-doing my rear e-brake assembly and rotors, I noticed my rear diff cover is leaking, it's pretty rusty, so I ordered a new cover. Went under the truck last night to check things out, and the only place I can see where you would fill it back up is on the top toward the front there is a 3/8 bolt with what seems like a rubber plug around it, just under that, there seems to be some sensor plugged into the housing. Am I correct, is this where you re-fill the diff ??? I see on the tag is says 74-140 synthetic, Anyone know exactly how many quarts I will need.. Thanks Chris...

P.S. Ford parts guy said no gasket is required, just use RTV, is this also correct ??

 

No, and yes. The fill plug is on the FRONT of the housing, driver's side, just above the centerline of the pinion shaft. It takes a (1/2"??) socket extension and a fair amount of torque to loosen it up. Sometimes a bit of heat from a propane torch helps remove it. Make sure you can remove the fill plug first before you pop the cover. There's nothing worse than draining it, replacing the cover, and realizing you can't refill it.

As for the cover, yes, just use RTV. I've never had any luck using a gasket, and the RTV has never leaked on me. Just make sure you get both surfaces squeaky clean (brake cleaner works well) and let the RTV cure as long as possible before refilling.

-Joe

 

75-140 is correct, and if it is a limited slip, do not forget the friction modifier.

 

Thanks for the replies guys. Guess I'm gonna have to crawl back under there and find that plug. All I saw last night was a 3/8 bolt and a sensor plugged into the diff right below it.. Does anyone know how many quarts she takes, or point me to a place to find out... Thanks again..

 

Page 264 of your owner's manual.

3.3 liters, or 6.9 pints.

edit... that's about 3.5 quarts... refill it to just below the bottom of the fill plug opening.

-Joe

 

alright, found the plug, was barely snug, wheeew,,, got the new cover and 4 qaurts of 75-140, thanks a lot,,, one last question ,,, I think. I'm in new york and its been ridiculously cold and I dont have acces to a heated garage, is it o.k. to proceed with this job or am I going to have problems with the RTV. It says on the package 1 hour drying at 70 degrees and 24 hour cure, longer in colder temps but it does not say anything about being too cold,,, is in the 20's here... Thanks Chris...

 

That's a good question... I'd be inclined to say that it's going to take a loooong time to cure at below-freezing temps. Obviously the longer you wait to refill it, the better, but if you can't wait, you can't wait. I'd probably keep the tube in your pocket until you need it, otherwise it's going to be like trying to squeeze play dough out of a syringe!

Also, with it being that cold, you're going to have issues with the gear oil draining... not necessarily a bad thing, but it's going to make it difficult to get it to stop dripping long enough to apply the RTV to the housing. Your best shot would be to apply the RTV to the cover, then hold the cover in one hand and shoot the diff with brake cleaner, blowing the gear lube back away from the lip, then quickly apply the cover before it flows back over the edge. It's going to be tough to juggle it, but it should work.

Also, if you're looking to drain as much of it out as you can, try driving it for a while to warm up the oil a bit... in sub-freezing temps, it's probably not going to make that much of a difference, but every little bit helps.

Finally, if you're not putting the frame up on stands, at least drop the spare tire to give yourself some room to work. I'm 6-1, and could almost sit in the spare tire well when I was changing my shocks with the truck on all fours.

-Joe