Today I was changing rear diff and transfer case fluid. Rear diff change was no problem. While waiting for the RTV to set I went to change the transfer case fluid. I moved the drain pan under the transfer case and started to take off the fill plug, which was not very tight at all. Good recommendation on another FTE thread to make sure the fill plug isn't frozen before draining.

I pull the fill plug and I'm guessing 1/2 qt or more fluid comes out. Not expecting much fluid to come out it goes everywhere. There was enough head pressure to shoot it past the drain pan.

So my question is where did it come from? I lost all my truck records and can't remember when or where I had it changed last. The design of the transfer case would make it very tough to overfill with out making a huge mess.

Do you think the transmission could be leaking into the transfer case? Not sure if this possible. I checked the transmission level and it was a little low.

Truck is 2004 5.4 SCREW 4x4 with 137K.

 

On a lot of designs the transmission can leak into the transfer case. I'm not sure if this is one of them or not.

 

The tranny can definitely leak into the transfer case. Looks like its time to take them apart

 

Apparently this is a known problem. Put some Lucas Transmission leak stop in. Hopefully this will fix it. I doubt it but worth a try. I guess the transfer case can only hold so much fluid and then it will start to leak. Looks to be about $400 to replace the seal.

https://www.ford-trucks.com/forums/1...sfer-case.html

transmission fluid leaking into transfer case problem??? - Ford F150 Forum - Community of Ford Truck Fans

 

Bowkill, I took my 04 in for a trans fluid change (102,000 mi) and it had the same thing. Trans was 2 qts low, T-case 2 qts hi. They pulled it, replaced the seal and reinstalled. In all, it was $527.05. Ouch! Also, when they pulled the drive shaft, the rear pinion seal leaked. This is also a known issue.