Transfer Case Problems

[First]

All,

I recently replaced the rear seal on my transfer case (2002 2500 HD). All was fine until I pulled a tractor which was roughly 8000 lbs. Shortly after this the transfer case started leaking again from the main seal. This was an expensive fix and don't want to do it again until I determine why this is happening.

Thanks for the help,

Scott

[cowboywildbill]

Could be that the new seal was damaged while being installed, which is not unheard of.
Or you might have a bad yoke. They had to replace the output shaft seal on my 07 twice. Then they replaced the seal again and a new yoke, that solved the problem.

[First]

Looks like it wouldn't hurt to go ahead and replace the yoke just to make sure. The guy that replaced the seal did complain of the difficulty in replacing it. Makes me wonder if it was damaged during the install?

Thanks for all the help,

Scott

[cowboywildbill]

Sometimes when they replace the seal and don't use the correct seal driver, or get too heavy handed with the hammer it will knock the spring off of the inside of the seal.
The yoke is a tad $ pricey $ just to let you know. Good luck and let us know what you find.

[DmaxMaverick]

There was a time I couldn't count the number of output seals I replaced in a month's time (multiple vehicles, not just one). The best method I've found to do it is simple, requiring either no tools, or only a dead blow mallet:

If doing U-joints at the same time, remove the U-joint from the front yoke, and install it after the seal is replaced.

Ideally, the seal should be replaced with a sleeve in place, to prevent the compression spring from getting dislodged. You can spend a bunch of money on a set of sleeves, or use the one you already have, the yoke.

Ensure the outer surface of the yoke is clean and free of corrosion or burrs. Polish it up if you have to. This will ensure the longest seal life. You could get extreme with this, and have it professionally polished and plated. Works really well, if you have the time and money (not really much of either, if you have a shop nearby).

Locate a piece of pipe (thick walled, not tubing), at or slightly greater than the outside diameter of the seal (and outside diameter of the pipe, with enough edge thickness to fully engage the seal metal, NOT the inner flat of the seal, which very often distorts it), and cut it just a bit longer than the space between the fully inserted yoke and the receiver outer surface (tranny output housing), plus the thickness of the seal. Shorter is better, with as much spline engagement as possible. Use a pipe cutter or lathe, not a hack saw (unless you are really that good). It must be cut square at both ends. The key to good seal seating is square insertion, and very small incremental blows (take your time....). Use some RTV, and smear a thin film onto the seal outer diameter, and receiver inner diameter (I know, "but the seal already has sealer on it", but do it anyway). This does 2 things: acts as a lubricant (before it cures), and seals it, really (after it cures). If using the yoke without the driveshaft, insert the pipe over the yoke, align the seal into the receiver, and push the yoke onto the spline until it engages the seal. Make sure everything is square, and gently (like nail driving) begin tapping the seal in, by striking the yoke between the U-joint holes (hit the end of the yoke tube, not the U-joint holes). If everything is square, it should insert in a dozen or so blows. Stop as soon as the outer surface of the seal is flush with the outer surface of the receiver, unless it bottoms first (you'll know if/when this happens, it's obvious). Do not drive it in past flush. Stop. That's it.

If the U-joint is still attached to the yoke, do as above, only use the shaft as a slide hammer, holding the pipe against the seal, keeping it square with the receiver. Use some ATF to lube the inner and outer of the yoke. You only need about 2" of throw to give all the blow force it needs to seat the seal. This actually works very well, and often better than the high-dollar installation tools. A bit awkward single-handed, but a cinch with an extra pair of hands.

Remove the yoke and pipe, then continue with the reinstall of the shaft. Be sure to liberally lube the yoke spline with some quality high pressure synthetic/lithium grease to prevent the "spring wrap bump" condition.

It also helps if you can do this with the rear of the truck (gearbox) higher than the front. This prevents ATF from running out as the yoke/seal is removed. Or....Just drain the gearbox ahead of time.

[First]

I hope to get started on this in the next few weeks as my travel schedule is very hectic. Thanks Cowboy Wild Bill and DmaxMaverick for the very informative information. I will let you know how everything turns out.

First

[CoyleJR]

First,

I originally posted the below information on 2-3-09. I now have 150,000 miles on my truck with no leaking. The transfer case fluid only leaks when driving and does not show up on the U-joint. I was suprised when I found the source of the leak. If you are lucky you will be able to fix the leak for the price of some JB Weld.

John

--------------------------------------------------------------------------------
I have a 2006, Chevy, D/A, CC, DRW, LBZ, 4X4, with 123,860 miles. Recently it was spraying transfer case fluid on the bottom of the cab. It took some time to locate the precise cause of the leak. It turned out to be the front driveshaft yoke leakng behind the U-joint. On the back of the yoke there is a cap much like a freezeplug and it was seeping fluid around this cap. I did not need to replace any parts. I cleaned the area around the cap and the yoke and sealed the seam with J B Weld. It has not leaked a drop since and it is towing a 38 foot, 16k, 5th wheel full time.

[MikeyB]

I have a 2006, Chevy, D/A, CC, DRW, LBZ, 4X4, with 123,860 miles. Recently it was spraying transfer case fluid on the bottom of the cab. It took some time to locate the precise cause of the leak. It turned out to be the front driveshaft yoke leakng behind the U-joint. On the back of the yoke there is a cap much like a freezeplug and it was seeping fluid around this cap. I did not need to replace any parts. I cleaned the area around the cap and the yoke and sealed the seam with J B Weld. It has not leaked a drop since and it is towing a 38 foot, 16k, 5th wheel full time.


Funny! I had the same problem and thought it was the dreaded hole in the transfer case. Found mine was leaking in the same spot as yours and fixed the same way with some JB weld.

Mike

[First]

Thank you gentlemen. I have been on the road for quite some time now, but hope to start working on my truck in the next few weeks.

First

[First]

Gentlemen,

Thank you all for the advice. I ended up replacing the yoke with a new nickel plated GM one and also replaced the rear seal. Since I've driven it about 5,000 miles and have not had any leaks or problems. One thing I did notice was that the new yoke was ever so slightly larger in diameter once we checked it on the micrometer. Which I think would help. Thanks again for all the help.

First:)