i have a 97 f-150 with the 8.8" and it has been starting to leak, so replaced the gasket thinking that that might be the problem, but it wasn't, and it still leaks now. What could this be? Im thinking of getting a new diff cover just so i can elimiate that as a problem.

Thanks!

 

Use a good RTV silicone forget the gasket. Or you could have a front pinion seal leaking.

 

Indeed, ditch the gasket. Clean both surfaces with something that won't leave a residue (e.g. brake cleaner), let them dry. Apply a generous bead of silicone to the surface of the diff cover. I prefer to use RTV as it seems to stay flexible longer. Place the cover on, and EVENLY torque the bolts down. Don't reef on one then do the rest.... that's a sure way to warp the cover. Finally, allow the silicone to set-up as long as you possibly can before refilling the axle. Overnight isn't bad if you can be without it. I've always gotten away with a couple hours at least.

-Joe

 

My 97' started leaking at the pinion seal about a week after I added a set of leafs to the rear spring packs. When broken down there was some ugly looking goo in there so we pulled the cover and changed the fluid. Make sure you use the right stuff when changing it and forget the gasket. The RTV Silicone worked awesome, make sure to really clean down both surfaces and it wouldn't hurt to wipe it down with mineral spirits before sealing it back up. I have not leaked yet...