kellio

Hello,
I am stumped. I own a 1999 2500, 4x4, AT, dodge diesel quad cab. There is a box mounted on top on the right hand side (looking forward) of my front axle. There is a ~3/8" rubber hose and 2-wire connection on top of the box. The tube has disconnected itself from somewhere in the engine compartment or transmission and was dragging on the road. The hose is about 36" long. There are no leaks apparent from engine compartment or auto transmission. Smelled the end of the hose - no smell (not transmission fluid, oil, diesel or coolant). What is this box? and where does this hose go to? Looks like maybe a vent hose, but I am not sure and don't feel real comfortable driving my rig until I find out what's up with this hose. I have tied it off for now. Help, please...

bnold

Vacuum hose for engaging front axle??

jrs_dodge_diesel

Sounds like it to me. Does your cruise control and vents work? If the cruise doesn't work and the air only comes out of the defrost vents, no matter what the **** is set at, then you have a very large vacuum leak. Most likely caused by that hose being unplugged. Before Dodge started using live axles up front they used vacuum actuated CAD (central axle disconnect). As far as where it goes, I have no clue, I know someone with a 4x4 can tell you though.

kellio

Thanks, excellent info. Now if I knew where that hose connected.. Maybe the intake manifold somewhere?

SMOKNISB

You are probably looking at the CAD's unit. The central axle disconnect for the 4 wheel drive. There is a vent hose that is connected to it. It is a hose that runs up by the shock mount and is just venting the diff. There is also a set of two vacuum lines, but they are alot smaller than 3/8" hose. There is also a plug with 2 wires for the switch that indicates it is engaged. From the sound of it, it is probably the vent hose.

Marks99

Ditto - that's how mines set up. The end of the 3/8" hose is clamped to the inner fender well, kinda under the air intake box - kinda hard to see/find, just has a plastic check valve sort of thing on the end of it.

kellio

Thanks Smoknisb and Marks99. The CAD system is exactly as you stated. I figured it was a vent of some sort because my cruise control still worked and I could not find anything on the engine/transmission/transfer case that would accept this hose. I'll look on the fender well for the check valve. The diagrams in service manual show the same setup. Again, Thanks for you help.

1-5-3-6-2-4

I just put my BHAF in today. That breather terminates directly under the stock airbox. I only saw it when I removed the bottom of the stock box. Its clamped to the inner fender. Its not a check valve on the end though, its a vent. allows air in & out. thats why its up high cause you will take water into the diff during water crossings if it were down low. same goes for transfercases and transmissions. and if your breather is plugged you can potentially blow seals out and create leaks.

biododge1

if that is the vent, what about the axle vacuum line. mine is ran from the transfer case gear selection switch to the axle. you didn't mention it so maybe thats it.

SMOKNISB

It is the vent line, he said it was 3/8" hose. There are two vacuum lines and they are very small.

kellio

The two vacuum lines are properly installed and run from the transfer case. I guess its time to take my AFE air intake off to look for this fitting. Also, I'm having difficulty finding where the hose clip clips to. Perhaps it will all come together when the AFE comes off. Thanks for the info smoknisb.

crobtex

It probably "snaps", pushes, into a hole in the frnder housing.

Marks99

Yes - mines just has one of those regular plastic snap in hose clamps things.

And as far as the check valve thing ... it is just a vent cap ... not sure why I called it a check valve

kellio

Well, I took off my air intake...nothing there to hook the hose to. Must have came off the hose as it was dragging down the highway. I'm going to get a small air breather with a 3/8" connection and connect it to the existing hose and mount it to the inner fender well. Should work just fine.

kellio

Job complete. Couldn't find a breather at the auto shop so I improvised with a small fuel filter. Routed it up to the engine compartment and mounted on the passenger side front fender. Thanks for everyones help.