This might be a stupid question, but here I go. I’ve got a Buick 10 bolt posi differential. I need to replace the cover gasket as it’s leaking badly. Is the Buick 10 bolt cover the same as a Chevrolet 10 bolt cover? I’m having trouble finding a cover gasket when I search for Buick 10”. Thanks in advance. Allan
When replacing the gasket, should I be putting RTV on the faces of the gasket? What’s the capacity of the diff? I’m wondering how much limited slip oil to buy. That should be it for stupid questions…… tonight. Thanks in advance. Allan
I've never used a gasket just cleaned and wire brushed both cover and housing and went straight to permatex right stuff in a can and never looked back. 20+ yrs and hundreds of diff covers and never had a problem.... ...
I'm remembering the days when a fella could go to the parts house, select a sheet of gasket paper the right thickness, & using his pencil, he would trace the outline of the cover & holes. Then, with scissors & 3/8'' hole punch, he would craft a gasket ....
^ I still do this...except I order gasket paper online now Not one good parts house near me. Even napa sucks.
You may want to sand blast the outside of the cover and see if there are any pin holes in it. If no holes, give it a good coat of paint. Looks mighty rusty.
Well, I think I know why it was leaking…… Unfortunately I couldn’t find Right Stuff up here. I bought some Parmatex Ultra Black which I also read good things about. How do you lay down the RTV on the cover? I was thinking down the center of the flange and then inside of the bolt hole? How big of a bead do I put down. This is the first time I’ve “serviced” a rear diff. Is there any need to clean the diff/housing before I button it back up and put new oil in it? ‘Thanks in advance.
I’m definitely going to give it a good cleaning. From the inside the cover looks good. The car threw a rod before I bought it so the entire underside of the car is coated in oil. Between that and the leaking cover, it looks like most of it is oil buildup. I’m soaking it now. Allan
@Al T it has to be clean and no oil or it will leak. I just run a bead down the middle of the lip and go to the INSIDE of the bolt holes all in one pass. Then come back and go around the outside edge of each bolt hole completing a complete circle around each bolt hole. Let it set a few minutes, while setting I wipe off the the rear end housing mating surface again. When doing this I always use brake kleen, carb cleaner etc to final wipe the housing and cover with before putting rtv on it. Then I carefully lift the cover into place, not touching the housing yet, I align the holes best I can then mate them together. I try not to move the cover around too much, as I don't want to thin out the permatex on spots. Start 1 bolt then install them all loosely then push cover tight against housing and snug up the bolts. WHAT I LOOKING FOR is a uniform edge of permatex around the cover squeezing out. Once all is good I tighten them down, give it about 30 minutes and fill up the oil ! All done !! ..
I couldn’t find the Valvoline VV820 up here either. This is all they had for limited diff fluid. Will it suffice? Thanks in advance. Allan
I’m heading to St. Louis in a couple weeks and need to get this back together so I can get it off the lift and get everything organized for the winter. There are no covers available in Canada and there was no guarantee I’d get one ordered from the US in time, so I ended up cleaning up and painting the existing cover. A replacement would have been the best solution, but I think this will work. The cover is still really solid, just not pretty.
Check to make sure it’s flat, it looks like it has bends on the lip. I have all ways had a problem with the covers weeping with rtv. so last time I used a blue fel pro gasket and per instructions both surfaces clean and dry, no leaks in years.
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