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Old 12-03-2018, 03:58 PM   #1
crsgmc
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Leaking Pinon Seal

When I purchased the truck the pinon seal was weeping, not enough to drip so I worked on other problems. Now the seal went from weeping to leaking. I purchased a new yoke (USA standard gear)and AC Delco triple lip pinon seal. The yoke had an extra collar with it that I think is to be used with the newer triple lip seal. I also replaced the back two U joints. Everything went fine and after the repair I drove the truck about ten miles and it is still leaking. I checked the vent hose to make sure it was pressuring the differential as the oil heats up. The line was clear. It is not leaking a lot. Do you think that it might wear in and stop leaking. When I installed it was around 30 degrees so maybe it is just stiff. I am probably wishing on the problem going away. I guess I will tear it apart and try another seal, not sure what else to do. Anyone have any suggestions why it is still leaking? I did a lot of internet searching but nothing was real helpful.
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Old 12-03-2018, 04:17 PM   #2
speedygonzales
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Re: Leaking Pinon Seal

Quote:
Originally Posted by crsgmc View Post
I checked the vent hose to make sure it was pressuring the differential as the oil heats up.
Would that be relieving pressure?

Did you check the shaft to be sure it wasn't grooved?
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Old 12-05-2018, 10:40 AM   #3
crsgmc
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Re: Leaking Pinon Seal

I replaced the yoke with a new one, so it is not ringed from the old seal, it is brand new. My message was a little confusing, I checked the breather hose and it was not plugged. If it was, as the oil heated up the differential would be under pressure causing it to leak.
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Old 12-05-2018, 12:41 PM   #4
speedygonzales
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Re: Leaking Pinon Seal

Then the logical assumption is you folded over a lip.
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Old 12-05-2018, 05:27 PM   #5
crsgmc
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Re: Leaking Pinon Seal

Thanks for the responses that were posted. I always appreciate when people post final results on what fixed the problem. In my case I guess it was nothing. I drove the truck for another 30 miles or so and then cleaned off the bottom of the differential real good. Just drove the truck about 20 miles and there was not a single drop of oil on the differential. I am not sure but maybe because it was cold when installed, it took the seal a few miles to mold itself to the yoke shaft. So if someone does a pinon seal replacement and it leaks for the first 10 to 20 miles don't panic. If it is still leaking after 50 miles you probably have a problem that is not going to go away.
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