Topic: Gear oil leaking from transmission into transfer case

[willig2]

Hello all,

This is my first post so thanks for the help in advance.

 I have a 1984 4Runner with the dual case setup.  I've had this modification for around a year or so with no issues.  Just recently, I've started noticing gear fluid leaking onto my dual case cross member skid plate.  At first, I thought is was the output shaft seal.  I have replaced this and the leak still appears.  My buddy who helped me install the dual case set up thinks that somehow, gear oil is leaking from the manual transmission into the transfer case which overfills the case.  The last time we checked, about 150 miles ago at my last oil change, the transmission was low of fluid and the transfer case was overfilled.  We extracted fluid from the transfer case and added to the transmission.  No leaks for a week or so.  Now, the leak has reappeared.  Any ideas? 

[OVRAROK]

Transmission output seal .

[captainobvious]

Transmission output seal .

correct. replace ASAP. high speeds will pump all  gear oil into transfer case overflowing it at the stick and with no/low oil it will ruin the transmission

[OVRAROK]

correct. replace ASAP. high speeds will pump all  gear oil into transfer case overflowing it at the stick and with no/low oil it will ruin the transmission

And be careful when installing t case, you can damage seal just shoving t case in.

[willig2 [OP]]

Thanks guys I appreciate the information.  How difficult is this repair going to be as I will be doing it in my driveway?  Any helpful hints you could offer or anything I need to pay attention to or watch out for?  Thanks again.

[OVRAROK]

this is a pretty straight forward task. you will be taking one side of both drivelines off, so make sure your on a level parking surface, chocks the wheels, and set e brake if you have one. mark the drive shafts before removing from transfer case, drain fluids from t case and transmission. I use a 2x4 or equivalent to support transmission from inside the cab, as the only support for transmission and t case is the mount on the t case, you could use a jackstand from the bottom, but supporting from inside give you a little more room under the truck, remove tcase bolts that attach it to transmission. at this point you can place floor jack under crossmember, remove 4 bolts that hold crossmember to frame, and slide rearward to disconnect from transmission, then slowly lower down. being your first time I would highly suggest a friend to help, one guy working floor jack, other guy supporting t case when coming down. once t case is removed, you be able to see the output seal on transmission. I would highly recommend marlin crawler output seal. once new seal is in, lightly grease seal, make sure to use caution when putting t case back into transmission, as not to harm new seal. oh, and don't forget to remove t case shifter before removing t case, torque all bolts to spec

[willig2 [OP]]

Awesome information.  I can get a helping hand for sure.  Thanks again.