T-Case Oil Leak Puzzle

[awalts]

Hello all,

I currently drive a '98 2-dr Tahoe, Z71. The T-Case in the truck is a NVG246 (RPO NP8), and before anyone asks, yes it has blue Auto-Trak II fluid in it.

Anyway, I had a bad vibration around 60 mph, so I took the driveshaft in and had it balanced with new universals and a new yolk. Good news: vibration is gone. Bad news: I now have a nice t-case oil leak from somewhere near the rear output shaft opening.

I did what any good person would do and I put in a brand new original GM rear output shaft seal. It did not fix the problem. Upon further investigation, it appears that the leak is coming from the yolk itself. The spray pattern on the underside of the body is above the u-joint, the "cap" at the end of the yolk is soaked with oil, and when the truck sits, oil drips from the u-joint.

My question is what could cause the yolk itself to leak? Assuming that's where the leak is, how does one fix it?

Thanks in advance for the help.

Alex

 

[awalts]

Follow-on:

Did some more research. Seems that some yolks are vented and other are non-vented. Now since I never had this problem until I changed the yolk, is it possible that the guy I brought this to put in a vented yolk when it should be non-vented?

Also, the rear output shaft seal has a little tiny vent hole in it. Doesn't this serve as the vent, and thus the yolk should be non-vented?

If the yolk is actually supposed to be vented, is the issue just the spline seal on the yolk spline?

Lastly, if this yolk is vented and it's not supposed to be, can I just shove some silicone down into the spline? Not a ton, but just enough to seal it up?

 

[lesterl]

Good questions, I don't have any answers other than to ask if you called the guy who did the work?

 

[Army74]

Ive got a 97 tahoe lt. Manufacture date is 12/96 so i know its early 97. 4l60e 4x4 trans no reverse drive is so so. Bought a trans it came from 99 tahoe 4x4. But guy said it was 97. Ive been told i can only use a trans from 96-97 due to 99 having a two piece case instead of solid case. Was wondering if anyone has run across this. I currently live in michigan