I purchased one of the Ford OE aluminum 10.5" Sterling differential covers for my '01 F250 4x4 crew from ED the Parts Guy (FYI they say he's back tomorrow ). Anyhow, The mating surface on the cover has a groove that looks to me like it's for an O-ring gasket, but there is no such animal. I purchased Permatex RTV designed for differentials. So, my question to you guys who installed these is where did you run the bead, on the inside, outside, or in the actual groove. Appreciate your input as I'd like to do this Saturday.

 

I ran the Permatex RTV into the groove and installed the cover. No leaks at all after 6 months, so I guess adding sealant to the groove was the right thing to do.

The Permatex used was the fast-drying variety so the differential could be filled right after installing the cover.

Lou Braun

 

I ran the bead down the groove also, over a year ago and no leaks.I put it on and waited until the next day to fill it.

 

I ran a bead along the middle of the flange and around the bolt holes on the diff cover, bolted it up and put oil in about an hour later... that was 23K miles ago... no leaks yet lol.