Air Presure Issues

[Monty]

I can't seem to build much presure in my air system on my M54, it builds around 15 psi and thats it. I pulled apart the air govener and cleaned it and reinstalled it but it still won't build more than 35-40 psi?
I looked through the manuals that I down loaded but neither one explains the air system in depth, could it be that I need to adjust the air govener (does turning it in increase the air presure).
The compressor looks to be fairly new considering the condition that it is compared to the dirt on the engine but I purchased the truck used and I'm not sure.
If someone can steer me in the right direction or if they have a number for a TM that will give me some answersI would be much appricative.

Thanks
Chad

 

[cranetruck]

Check the relief valve, it may be stuck open (item 6 in the image).
Do you hear any hissing sound(s) after you shut off the engine?
How is the tension on the compressor drive belt?

 

[WillWagner]

Could be the unloader in the compressor too.

 

[acetomatoco]

Tank drains shut? Service and Emergency glad hand valves off? Tranny shift valve? Load the system with a remote source and listen for leaks, your engine need not be running for this.

 

[emmado22]

get an shop air compressor, make up a double male air hose, and plug it into the air "port" underneath the passenger side of the dash. That will air up the system, and you can listen for leaks without the engine on. (dont forget to open the valve on the port)

 

[Monty]

Check the relief valve, it may be stuck open (item 6 in the image).
Do you hear any hissing sound(s) after you shut off the engine?
How is the tension on the compressor drive belt?

I tightened the belt since it was very loose, I'll take a look at the relief valve.

Thanks
Chad

 

[Monty]

Tank drains shut? Service and Emergency glad hand valves off? Tranny shift valve? Load the system with a remote source and listen for leaks, your engine need not be running for this.

This may not be the right way but i thought if I could hook up an air line to the emergency glad had that I could air up the system. I made an adapter and hooked it up to the glad had and turned the valve on but i didn't show air presure on the gauge nor did i get any air out of the tanks.
I'll look into the tranny shift valve.

Thanks again to all who replied, can anyone recomended a TM number so I can study up on this.

Thanks again

Chad

 

[Monty]

UPDATE,

Added air to the junction under the dash, aired up and heard air leaking under the trans tunnel, I removed the trans cover and found there's three line that run to the top of the transmission. Between the two center lines there is a port ( maybe air exhaust?) The air was leaking out of there, along with the hose that goes to the wiper motor's. I plugged the port and started the truck with a process gauge ( 4 inch face accurate to +/- .25 psi)installed underthe dash. With the throttle locked at 1050 rpms the best air presure that I could get was 47psi???????? If I rasied the rpm's to 1500 the Presure would climb to 55 psi.
Questions

1. What's the valve on top of the trans used for? What is the center port for.

2. I have the 9-2320-211-20 manual that I printed off of S.S. It doesn't get detailed on the air system can someone recomened a better TM.

3. The air govener, is it used to adjust for the system presure?

Thanks all
Chad

 

[BEASTMASTER]

on the gov. turn the big nut all the way in,then turn the 13/16 one in about 5 or 6 turns. that should put you're pressure about 120 lds.in to increase out to decrease .then tighen lock nut.

 

[Monty]

on the gov. turn the big nut all the way in,then turn the 13/16 one in about 5 or 6 turns. that should put you're pressure about 120 lds.in to increase out to decrease .then tighen lock nut.

Thank you I will try it this week.

Chad

 

[m139h2otruck]

Your transfer case shifter air valves are leaking on top of the transmission. Try some air tool oil in the air intake of the compressor and check the bolts that hold the valve bodies together on the side of the shifter top. Look through the battery door and use a long extention. Cycle the shifter back and forth between neutral & reverse to work the valves after you add the oil. Does the transfer case shift the sprag when you go between neutral and reverse? At the worst, you can disconnect and plug the feed hose to these valves and run without the front axle engaged.

 

[Scrounger]

As already posted the air valve(s) are leaking. You may want to try starting the truck and placing the transmission in first or reverse and see if that stops the air leak. The valve seals don’t like cold weather especially when they get old, kind of like the vehicle owners. After the pressure builds up the seals will usually do there job. At some point in time the seals will need to be replaced and there is a posting on the site about it.

 

[Monty]

Thnks again I'll take a look at it this week.
So is the center port an exhaust port?