Alright, so I've searched up and down for a vacuum line diagram for a 5.9L V8 RAM 1500 4x4, and have come up empty-handed. Here's the deal: I was looking into the engine bay, and saw that there is a hose coming from the axle shift motor, but it isn't connected to anything; it just has a coupler at the end of it where it's attached to the frame of the truck. I can only assume it's a vacuum line because it's not leaking any fluid. However, I can't find where that line should be drawing vacuum from, which means that I have a vacuum leak somewhere. I looked all over the place for the other half of that line and can't find anything. Here are a couple of pictures to hopefully illustrate, and yes, I am aware that my axle is leaking.

 

its just the axle breather tube. has nothing to do with vacuum.

 

so, it's supposed to be open-ended like that?

 

I cant really tell by the pictures, but is the line on top? And is it not the breather vent tube?

 

That's the breather hose. The two smaller lines below it are for the vacuum and they go up to the pass. side frame and goes back to a plug on top the transfer case.

 

Should that breather tube be facing downward to keep water from getting in the axle tube, then?

 

It has (or should) have a little plastic cap on top to prevent water from going in there.

 

On a related note - as you saw from the pictures I posted, my front axle leaks at the shift motor, and recently (as of about two weeks ago) ive been hearing a pretty noticeable humming sound coming from somewhere around the front axle. I'm running 315/75r16 kumhos and they're about ready to be retired, so I'm having trouble identifying whether the humming is coming from the tires or the differential. I guess the question is: even if the diff is low on fluid, would it hum if the front gears aren't engaged? I don't want the thing to lock up on me going down the road, and I haven't been able to find the time to fix that leak. Any input would be greatly appreciated.

 

How about just checking the fluid level and adding once a week? Until you can get to fixing the leak. Or are you just going to let it run dry and wonder where the humming is coming from?

 

To replace that shift cover gasket only takes about twice as long as it does to top off the fluid