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Discussion Starter · #1 ·
How much oil do you folks run in your rear end? Is the stick your finger in the whole and feel for it trick a good method? I have a gear set with a leak. I changed the pinion seal applied a small amount of silicone to the splines and bolted it back together. Still leaking! The yoke is used but, it doesn't have any large imperfections. I'm wondering if I just over filled it and the oil is just overwhelming the seal. I put about three quarts in it. The rear is a 742 case 4.30 gear with a clutch type posi if it matters. Also the seal is a leather type. I might need a new yoke. This is not a major leak. Just enough to leave about 2" spot on the garage floor. What do you guys think?
 
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aside from the bad seal you have,with car level, fill diff. till it leaks out the filler hole.silicone on the splines?
 

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Discussion Starter · #3 ·
mopar stu said:
aside from the bad seal you have,with car level, fill diff. till it leaks out the filler hole.silicone on the splines?
Yeah, I know -o When I first picked this rearend up it had silicone on/in the splines for the pinion yoke. We swapped yokes from large to small u-joint style and didn't put any back on. Anyway, thinking maybe it would be a little extra insurance I thought I would put some on the splines since I had it apart for the seal this last time. That was the way it was first assembled anyway. Never the less silicone on the splines and a new seal didn't help. The pinion yoke must be wore just enough to let a little seepage by. I havn't really looked but, maybe there is a better type of seal for a 742 case.
 

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The vent could be plugged letting the pressure build up at temperature too.
 

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With leather seals you have to lubricate the lip before installing, if not they will eventually leak or cause some squeaking noise.
But what you must do is find where the leak is actually coming from and then address the issue. Also check your vent like stated above. A full level for diffs is when the oil runs out on it's own and is level with the hole, not below the fill hole.

gt
 

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Discussion Starter · #6 ·
Thanks for info guys. The diff. vent is definitely worth looking into. I'm pretty sure I had the car up in the air on all four corners when I filled it. It is possible I just had the rear up though. I'll jack it up fairly level and remove the plug and see what happens. The leak is definitely in the pinion yoke area. Kind of hard to tell if it seeping between the seal and case or between the seal and pinion with everything assembled. At 240 ft/lbs. the pinion nut is a real pleasure to remove in the car. I don't think I'm going to change the seal again without a new or atleast diffrent yoke.
 
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