DRIVE SHAFT at T/Case OUTPUT SHAFT SEAL LEAKING AGAIN??????

[lmholmes11]

Ok thank you. I will replace the seal

[CoyleJR]

I just looked at the pictures of your TC leak and in my opinion the yoke is leaking at the freeze plug. The first picture shows an almost dry seal and yoke. The second picture shows a wet yoke and U-joint. The fluid is leaking from the freeze plug/flat wet area between the U-joint and the yoke shown in the second picture. Go to Walmart and buy some brake parts cleaner, JB Weld fast dry and a tooth brush size wire brush. Clean the flat area of the yoke (freeze plug) behind the U-joint and seal the seam between the round plug and the body of the yoke with JB Weld.
DmaxMaverick posted a link (read this thread) to an old posting that I had placed about this same problem. If you do replace the seal I would do the JB Weld fix just to cover all the bases.
Good Luck and let every us know what happens.

Merry Christmas
John

[DmaxMaverick]

I just looked at the pictures of your TC leak and in my opinion the yoke is leaking at the freeze plug. The first picture shows an almost dry seal and yoke. The second picture shows a wet yoke and U-joint. The fluid is leaking from the freeze plug/flat wet area between the U-joint and the yoke shown in the second picture. Go to Walmart and buy some brake parts cleaner, JB Weld fast dry and a tooth brush size wire brush. Clean the flat area of the yoke (freeze plug) behind the U-joint and seal the seam between the round plug and the body of the yoke with JB Weld.
DmaxMaverick posted a link (read this thread) to an old posting that I had placed about this same problem. If you do replace the seal I would do the JB Weld fix just to cover all the bases.
Good Luck and let every us know what happens.

Merry Christmas
John

I'm still trying to grasp this "freeze plug" you guys are sealing with J-B weld. Certainly you don't mean the yoke vent????? It's there for a reason, and sealing it will cause more serious issues than a little leak (output shaft bearing and pinion bearing failure, to start with). Proper packing of grease on the spline will prevent any leakage at the vent.

[CoyleJR]

DaxMaverick,

The yoke vent sounds like the correct name for the part. I never said to plug the vent hole in the middle of the yoke vent. If the yoke has a vent hole, I have seen many that did not have a vent hole in the center. My problem was with the TC fluid leaking from the seam between the yoke vent and the body of the yoke. I suggest that sealing the seam with JB Weld is an easy inexpensive way to make certain that it is not leaking.
If you look at Imholmes11 second picture you will see that the yoke vent/U-joint area is quite wet with fluid and the first picture of the seal/front yoke area is not very wet.
My truck has about 60k miles on the JB Weld fix and it has not leaked a drop.
Merry Christmas
John

[DmaxMaverick]

If we are looking at the same pic, what I see is a wet seal lip and tailshaft housing, with fluid "wicked" about 2/3 up the joint yoke. If the vent were leaking, the entire joint yoke would be wet, with more than just the trickle down the tailshaft housing. Also, there would be a significant amount of fluid at the outer area of the U-joint and the body pan, due to centrifugal affect.

In any case, there should be no fluid, or any significant amount, at the rear area of the spline yoke. This is disastrous, and will lead to a LOT of damage. The leak is only symptomatic. Fix the leak w/o sealer, or look forward to significant premature drivetrain failure. The "freeze plug" is no more than a dust cap, with an orifice to allow venting, and prevention of outside contamination. There should be no ATF on either side of it. If the cap is leaking at the perimeter, it is very likely there has been fluid under it, which caused it to leak, in the first place. Sealing the "leak" only hides the leak, which is a designed indicator of another problem (like a weep hole on a water or fuel pump).

Older splined slip yoke designs had a grease zerk, but these were discontinued. The reason for discontinuing was over-greasing, which caused the same problem as a leaky one. There should be only an air gap between the end of the output spline shaft, and the head of the slip yoke.

[lmholmes11]

Do you need a press for these u joints to remove? On the semis I've always used a press with an impact. Looks like just remove the snap ring and hammer the u joint out of the yolk? Does the yolk then just pull off? I've only done seals and yolk/u joint work on semis. Sorry for so many questions!

[DmaxMaverick]

Remove the driveshaft at the rear joint (4 bolts on 2 caps, mark the joint and pinion for exact reinstall, tape the joint caps on, so they don't fall off), then slide the yoke out of the TC. Nothing holds it in there but the shaft. Have a container handy, as there will be some ATF that will dump out once the yoke clears the seal (unless the level is very low, and/or you are pointed steep downhill). There's no need to disassemble U-joints unless you are replacing them. It's as easy as it it can be, so don't try to make it difficult.

[lmholmes11]

Thanks for the help Dmax, i plan to replace the seal ASAP. When you said that fluid could be disasterous there do you mean just by leaking out all the ATF out of the T/C? I have a 200 mile trip that I need to take the truck on tomorrow. If I keep an eye on fluid level should it be ok?

[DmaxMaverick]

Thanks for the help Dmax, i plan to replace the seal ASAP. When you said that fluid could be disasterous there do you mean just by leaking out all the ATF out of the T/C? I have a 200 mile trip that I need to take the truck on tomorrow. If I keep an eye on fluid level should it be ok?

Leaking out all the ATF could be disastrous, but I was referring to having the airspace between the yoke and shaft full of fluid. Fluid is not compressible, and will lock the fore/aft motion of the driveshaft (caused by rear end compression/retraction), to the TC output shaft. A "slip yoke" is used here for that very purpose. If it isn't leaking out of the vent, then that's not an issue. A leak at the vent indicates fluid where it doesn't belong, and sealing it compounds the problem. If the cap is leaking, in any way, there's fluid on the other side of it, and less air to allow for movement. Fix the minor leak now, or replace the TC later.

You should be OK if you keep an eye on the fluid level (I would do it, if necessary). 200 miles isn't far.