That's a nice looking cover! Can't believe that you're having such a problem getting the cover to seal, are you sure the cover is the problem? You mentioned a pinion seal also, kinda hard to confuse a pinion seal leak with a cover leak, maybe you had more than 1 leak. Could the housing be porous? It's rare but it happens.

BTW, I use a GM "paper" gasket with my TA rear diff girdle and it seals up perfectly

 

I thought pinion seal because it is damp on the underside of the housing and on the bottom of the pinion dust cap so I thought the fluid was dripping down to the lowest point on the axle and falling off. As I was replacing that I laid there and watched a small drip form on the bottom of the cover and fall, so there is definately a leak at the cover. I dont know the deal with the pinion seal though. The old one looked fine and im sure the new one is good.

I used the black rtv which is oil resistant and hi-temp. It worked fine for my 10b. I got the cover from blue torch fabworks.

 

i have a pinion seal leak right now thats pissing me off! but its not dripping oil like yours
i have maybe a penny size drip every week, gonna change it when i get the chance...

nice cover btw

 

hmmm, what would happen if you over-filled a diff?

Lets say you filled it up to the drain plug while parked on a steep driveway.

 

i think thats how i blew out my seal, i was filling it till it was running out the fill hole! its supposed to be like 1/4 inch below the fill hole. best way i have found to measure it is to stick your pinky finger in and have the oil right at the finger nail. the leaking is better also after i put a heavier weight in, i was running 75-90 now im running 85-140

 

I may try the heavier weight when I replace the cover as well. Fustrating problem. I loose about half a quart a month with this leaking.

 

The 9.5 14 bolt is supposed to be filled up to the fill hole, unlike the 10 bolt.

Have you identified exactly where the leak is?

 

As far as I can tell, there are 2 leaks.

The larger of the two is from around the cover. You can tell in the pic that around the top and the bottom are both wet.

The second has to be coming from the bottom of the pinion. I just replaced the seal and it still leaks, so I dont know what else I could do....its not scored or anything so I dont know why it is leaking.

 

Lets see if this helps. I took this right after I took off the yoke, and before I replaced the seal.

 

Can that just be the fluid running out from removing the yoke or was it all wet on the housing before you removed the yoke. Is it possible that your vent is clogged?