Front Differential Fluid Overflow Leak

[RammaR]

In my previous thread, I came to the conclusion that the horrible ratcheting / whirling sound underneath the truck on deceleration was from my transfer case. I'm planning on rebuilding it this weekend -- however now I'm starting to 2nd guess the transfer case or even worse afraid I have another issue.

The underside of the front passenger side is coated with a wet oily fluid that has occasionally left a few drops on the floor. Nothing too serious, I've followed the leak up to the highest point and its coming from the breather/vent tube out of the front differential. I checked the fluid level a few days ago after a decent size puddle formed and it was just a little bit below the filler hole. I changed the fluid last at 100k miles and it has 153k miles now.

Then tonight after being home for a few hours I went back out to the garage and smelt a burnt oily gear oil smell and looked under the truck and saw this puddle:

I haven't rechecked the fluid yet tonight, but it looks pretty clear - not contaminated. But what could be causing it to spew out of the vent tube? I didn't find any other similar threads when doing a search. Could this somehow be tied to the failing transfer case? Its my understanding that the front drive shaft turns all of the time, but when 4x4 auto is activated, the front differential is engaged. I haven't been in 4x4 mode recently, and definately not this afternoon.

Please let me know of any suggestions or things to check that might help diagnose this.

Thanks!

 

[CodePoet]

Been though any high water?

 

[RammaR]

Nope, none at all -- and the fluid doesn't look like the 'milkshake' that I've heard water contamination described as. I'm thinking of draining and refilling this weekend when I do the transfer case, but would really like to have an idea of why its happening.

 

[Blee1099]

check the pinion seal.. They are known to go bad on the D35 IFS.

 

[RammaR]

Is the pinon seal internal to the differential or something that can be checked from the outside?

 

[checkedout]

This is a common problem. Ford has a service bulletin on it. What they will do is remove the front differential so they can replace the differential cover with one that has a baffle on it so that the fluid will no longer be pushed up the vent tube. I'll see if I can locate the thread for you. What I did is replace the vent tube with a much longer one and mounted the end at the top of the engine compartment.

 

[checkedout]

Here's a thread:
http://www.explorerforum.com/forums/showthread.php?t=68406&highlight=FRONT+AXLE+FLUID+LEAK+VENT+TUBE

 

[RammaR]

Excellent, thanks!