Front axle pressure?
 

I have a 2003 H2 ,for some reason the front axle builds pressure and vents gear lube through the vent tube.It only does it when I tow my trailer on the interstate.If anyone knows what causes this please advise me of a solution.Thanks

Go through any water more than a foot or so deep?

Something in there is heating up the fluid to the point of venting out? Throw some water on the diff after you give it some stress driving. If it sizzles right away, you know a bearing or something is junk in there. Dont touch it by hand, you'll leave your skin on it.

Id change your fluid, you will be able to tell if its having some failure vs being over filled or flooded from going through deep water. Blow out that vent line while your down there, inspect it for cracks or leaks.

Chevy trucks had an issue where the vent tube connected into the diff - it was like a plug w/ the tube connected to it. If it wasn't seated in the correct position, gear oil would pool up on baffle and barf out occasionally through the vent tube. I dont believe the H2 diff has this though.

It's a known issue with H2's. I was looking at a used duece at my dealership that had the problem and talked to my service advisor about it.
Just can't remember what he told me, but they did take the truck back in the service dept. and took care of it. I think it had something to do with the vent tube by the exhaust, but like i said, can't quite remember.

There was a bulletin on it from GM. Use part number 5651682 filter and it will fix the problem

Thanks for the help. Havnt been in water at all. I will check it out and let you know. Does the filter go on the vent tube?

The only way a filter could be part of the problem is if it is not allowing air back into the diff. If it was somehow plugged or manufactured defective acting like a one way valve venting out only. If thats it, then somehow air is entering the diff by other means. Seal, crack, etc...