Hey guys, I'm new to FTE but I own an older Ford!
I have a 86 F-150XL 302 FI 4x4 W/4speed granny low.
I was topping off my 9 inch rear due to a slow front seal leak and when I loosened the fill bolt air pressure began hissing out. then fluid began pouring out after full removal of bolt: enough fluid to fill a 12oz can and then some on my carport.
Whats up with that? I topped it off,but I guess I need to know if I have caused damage or if this is normal.

 

it sounds like your vent on the rearend is clogged. causeing pressure to build up and blowing oil out of your seal thats around your yoke. eventually it will blow it from the other seals if it gets anough pressure build up. your vent is on the back usually close to the left side. it is a nipple thing that also holds your brake line splitter on the rearend. just unscrew that nipple and pull off the hose if yours is still on it. clean it up some and stick it back in. the hole inside the nipple should be about the size of a pin. any more questions just ask. i might know the answer to them

 

I'll check that out. It probably has mud covering it from when I pulled my buddy's Chevy Z-71 out for the 3rd time! Nothing like good ole Missisippi Gumbo to seal all the leaks!!
Thanks again!!

 

Sounds like it was over full also - that will help it leak past the seals. With the truck sitting level the fill plug also determines fluid level - only add fluid to the bottom of the hole.

At some time it was probably filled sitting on a slope and the axle housing collected the extra.