Air Vent, Whats it for

[SoundGuy]

The is an air vent under the hood on the firewall next to the air intake filter. It is venting air. I am trying to figure out what its for. I have looked in the TM's but without knowing what to look for I have not be able to figure out. All I know is that it use to hold pressure for a while with it shut off and now it is draining down in a couple of minutes. Any help is greatly appreciated. I hope I don't offend the "search for it" lords over here. I have looked.

Just a few note. The front wheel drive engages and disengages just fine

The wipers work just fine

The brakes work just fine and release a noticible burst of air when released.

I'm not sure where else to go and am having hard time tracing the line by myself

 

[treessw]

sounds like it would be something with the tanks. If you are losing pressure quickly after shut down, it could be as simple as a loose fitting or it could be the line is ruptured. As the truck is running so is the compressor so it will continue to feed the tanks but could also cause premature wear and require replacement sooner of the compressor. Long term you need to fix for safety and to keep your air tanks from bleeding out and maybe overworking the compressor, especially if it gets worse.

Ok I just re-read the post, I stand corrected, you said it is a vent. I will crawl out near mine in a bit a look at it, sorry about that!!!

 

[gimpyrobb]

The vent in the last pic is the brake system mwo vent. Originally, the fuel system and the brake syst wer T-ed together and vented in the same linee. That caused issues and a Modification Work Order was put out to vent them individually.

 

[SoundGuy]

I have checked for leaks and the only place it seems to be leaking is through the vent. I can hear and feel air coming from there until the pressure bleeds down. I want to get it fixed, I just don't know what to fix.

 

[SoundGuy]

OK stupid question, what is a mwo?

 

[KsM715]

The vent in the last pic is the brake system mwo vent. Originally, the fuel system and the brake syst wer T-ed together and vented in the same linee. That caused issues and a Modification Work Order was put out to vent them individually.

OK stupid question, what is a mwo?

See Gimpys Quote

In other words its an order put out to change or correct something. The tow bars had a MWO to put collars on them to strengthen them. Most trucks have a little triangle shaped tag on the drivers seat that is a MWO to install seat belts.

 

[gimpyrobb]

If air is leaking out of that vent, it is possibly your air pack. Are you sure its not leaking out of the grey thing mounted to the firewall to the right of that vent? That grey thing is the air govenor. It turns on the air compressor when pressure gets low and off when pressure hits 120(or whatever its set at). It is possible that needs lubed or rebuilt.

 

[DUECE-COUPE]

MWO, Modification Work Order. after a problem is identified and reported to TACOM, a team of technicians address the problem and determine a remedy for the problem. the remedy is tested and after it is approved, an MWO is published, distributed, and implemented by the level of repair that is responsible. Often, an MWO is completed and a tag is placed on the cab web on the drivers side of the vehicle so it is available for inspection.

 

[emmado22]

A MWO is the equivialent of a recall on a civilian vehicle.

 

[Digger09]

That looks like the vent tied into the air pack. Open the door on the drivers side floor were you check the brake fluid and it is probebly threaded into the cap on the air pack.

 

[SoundGuy]

ok, first of all thank you much for all of your help. It does seem to go to the tube on the top of the master cylinder and also connects to the air pack. I am guessing my air pack must have a slow leak. I will disconnect the exhaust air line from there tomorrow to confirm this. I guess this means I will be rebuilding or replacing an airpack. The strange thing is the airpack works just fine. I did determine it does not leak if I push down the break pedal.

 

[roalcoal]

ok, first of all thank you much for all of your help. It does seem to go to the tube on the top of the master cylinder and also connects to the air pack. I am guessing my air pack must have a slow leak. I will disconnect the exhaust air line from there tomorrow to confirm this. I guess this means I will be rebuilding or replacing an airpack. The strange thing is the airpack works just fine. I did determine it does not leak if I push down the break pedal.

I am having the same problem , did you have to rebuild your air pack? How did you fix it?

 

[SCSG-G4]

Roalcoal, that is a 2011 thread, so obviously the OP fixed whatever was wrong, but forgot to post the solution to his problem, which unfortunately is happening far too often. You may want to send him a Private Message (PM) and ask what his solution was.