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Tranny Fluid Dripping Out Back of Transfer Case

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Big6ft6, Mar 23, 2009.

  1. Big6ft6

    Big6ft6 Rockstar 100 Posts

    The rear seal on my tranny went allowing tranny fluid to dump into my transfer case, over filling it and causing it to drip out the back of my transfer case.

    Not feeling like laying in my driveway and dropping the transfer case myself...(I'm tired...just want my truck done) I swallowed my pride and took it to a local off-road 4x4 shop to have the rear tranny seal redone.

    Here is my question. I got the truck back (in exchange for $371)...and it still leaks!! Nowhere near as bad, but it still leaks.

    Before the repair, I had a 5 foot wide puddle of ATF under my truck. Now I just have an 8 inch wide puddle. It drips straight down from the U-Joint just behind the transfer case (just like it did before).

    Should I take it back to the shop? What could be causing this other than the trans still overflowing into the transfer case? Any other ideas?
  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    OK here's the deal. First of all if your transfer case is leaking out the rear seal it has nothing to do with the seal between the transmission and the transfer case!
    That being said you need to first off repair the rear seal. This can be done from the outside without removing the unit. If the driveline yoke is loose <wiggles up and down> you will need to replace the bushing as well.
    The seal between the transmission and transfer case is called the transfer case front seal. These deals get hard and leak. If the seal leaks the transfer case will overfill with oil. Useally the result is a leak out the vent, not the rear seal.
    I would in any event take the truck back and have them fix it! A reputible tranny shop would have changed all the seals during this repair.

    Jim
  3. Big6ft6

    Big6ft6 Rockstar 100 Posts

    Thanks Jim!

    You cleared up a big area of confusion for me. I didn't realize that the tranny dumping into the transfer case would normally cause a leak out of the VENT TUBE....that helps. I couldn't understand why people were saying my vent tube must be plugged....now I get it. They were saying in order for the fluid to leak out the rear seal...my vent tube must be plugged otherwise it would've leaked out the vent tube. Got it!!

    I know the tranny was leaking into the transfer case becuase along with the 5 ft puddle of ATF in my driveway, my tranny oil level went way down (didn't register on the dip stick) so that repair had to be done.

    But it sounds like the rear seal in my transfer case is ALSO bad and should've been repaired as well.

    I assume the seal is not expensive and the labor would've been minimal...but what about that bushing? Is that something that is pretty easy to replace if I need to?
  4. Crawdaddy

    Crawdaddy Thread Killer Extraordinaire Staff Member 5+ Years 1000 Posts Platinum Contributor

    This may help you with some insight: http://www.gmtruckclub.com/forum/showpost.php?p=66490&postcount=8 There's a seal in the 2wd transmissions that keep fluid from exiting the vent hole in the end of the u-joint yoke. If it goes bad it can leak out from between the u-joint ears. This seal would not be visible from the outside and can cause a pretty quick leak...we're talking perhaps a quart a day,which sounds close to the amount you're getting. Might wanna check this out as I'm sure the transfer case has something similar to this in it for the drive-shafts.
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The bushing can be changed with a special tool without removing the tailshaft housing. If you don't have this tool then you have to remove the housing to replace the bushing. It can be cut out with a bushing chisel. Not too hare to do with the right tools.
  6. paracutin

    paracutin Member 100 Posts

    I know this is a really old thread but I have a question directly relating.
    My seal is just starting to leak ever so slightly. How difficult is it to replace? Does anyone know the procedure?
    The yoke will move up/down about 1mm. I figured that wasn't excessive but should I replace the bushing while replacing the seal.
  7. TMair

    TMair Member

    If it were me I would try the seal first, if it is leaking just a little it could be the seal, the bushing helps hold back most of the fluid but a little can get by it, there should be a little drain hole behind the seal and at the bottom where the fluid that gets by the bushing can return to the tranny/transfer case, if it still leaks, and if you are careful you can remove the new seal with out hurting it to replace the bushing if needed.
    Terry
  8. Skeeter225

    Skeeter225 New Member

    What tool is needed for the rear transfer case seal. Mine is dripping fluid and I just added 3/4 quart to it today. I know that some of the older model transfer cases used to leak out the center of the rear drive. Mine seems to be leaking from around the yoke and it appears to be the seal.
    What might the seal part number be and what special tool do I need to remove the old seal. I have a friend with an Auto repair shop but he has never done a reseal on one of these tranfer cases with out haveing to remove the case and take it apart.

    If I can just pull the yoke and replace the seal with out dropping the case it would make it so much simpler.

    Thanks for any and all help.

    Skeet225


    Running 2004 Crew Cab Chevy DMax with Allison in her and 144,000 miles.
  9. TMair

    TMair Member

    You should be able to just remove the yoke and pull the seal, there is a tool for pulling seals, it has a hook on it that you can reach in and hook the back of the seal then pry it out, but you should be able to use a flat screwdriver to remove the seal, if there is a flange on the seal you can drive the end of the screwdriver behind that flange and pry it out, or you can drive the screwdriver into the seal just to the side of the rubber part, that will make a hole in the metal part of the seal then use the screwdriver to pry it out, many of these seals have been put in with something similar to red locktight, so it may be "stuck" in there pretty tight, just do not hurt the case, or scratch the bushing that is behind the seal.
    Terry
  10. Skeeter225

    Skeeter225 New Member

    What does the special bushing tool look like. The seal should be NO problem, but if I need to change the bushing as well I might just do that also. It is nice having a friend with a lift and such, so gaining access to the area is easy. How much movement should be in the yoke?

    Thanks for the help.

    Skeeter

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