Building air pressure

[Welder Dave]

I started my Ford L9000 with a Cummins M11 today. It builds air pressure fairly good to 100 PSI but from about 102 to 110 takes about 15 minutes. It gets to 105 and takes the longest getting to 110. There was a little air leaking from the air dryer when I shut it off. I think about 110 is the most it has ever made but I'd hear the brakes dynamite some times. Could it be from sitting for awhile and might get better? I use the truck off road so don't know if it's that big of a deal. The brakes work good. I was reading it can be good to take shop air and blow the lines out? Any other simple things to check or try?

 

[cuttin edge]

If I recall. The compressor has a min max. Not sure if it has merit but ive heard it's not good for your compressor to pump all the time. Could just be an old truckers tale. All I know is bad Governor, stuck unloader valve or a leak. TS could diagnose it blind folded standing on 1 foot eating pizza with both hands behind hi back

 

[Deere500a]

Dump air,air dryer & or air dryer cartage is probably due for service & use of winter alcohol inlet side on dryer disconnect let it blow out the airline from compressor see if any junk.

 

[Truck Shop]

Purge valve at dryer is probably defective--part of the leak.
D-2 Governor has a black finned cover screwed on one end-under it is the adjustment
for setting cutout pressure, it should cutout at 120 psi. Loosen nut turn in 1/8 turn
increments, counter sets it higher clockwise lowers, IIRC.
With pressure on the system and if hose is fabric over wire braded, those can leak with
age. Soap mix in spray bottle, soak entire length of hose to see if it's foaming/leaking.
That signal hose will run from dryer or reservoir to D-2 governor, when the hose leaks
it can lengthen the cutout/full build time.

 

[Pops52]

Im waitin to see the pizza trick…..

 

[Truck Shop]

Im waitin to see the pizza trick…..

Be waiting a long time, I don't eat pizza.

 

[Welder Dave]

I took pizza today but never ate it. I don't have much of an appetite especially when it kind of hot outside.

I started the truck today and have some better news. It took awhile but built pressure to about 116/117 and then the big release of air. I think it was the compressor cut out. I checked the air dryer and it wasn't leaking at all. Let the truck sit for awhile while took the bolts for a mud flap off. That was an ordeal in itself. Pressure dropped a little but still over 110 PSI. Started truck again to move it and let it build up to cut out again. Running the engine about 1300 RPM builds higher pressure much faster than 800 RPM idle. I think it's just a little finicky. Sometimes has a slight leak and other times it doesn't have anything you can hear. Not sure if I should be very concerned or not? Opened the drain on I think the wet tank and no water but a little oil residue on my thumb. It didn't have any noticeable oil blowing out. I didn't realize the drain blows straight out rather than down. That's how thumb got some oil residue.

 

[Truck Shop]

Then there was no issue to begin with.

 

[cuttin edge]

Sometimes the DOT will get you to pump your air down. Your air buzzer has to work, and there is a time limit on how long it takes to get back up to 120

 

[Truck Shop]

#20.
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[IceHole]

Sometimes the DOT will get you to pump your air down. Your air buzzer has to work, and there is a time limit on how long it takes to get back up to 120

Doesn't need to be a buzzer, just something that signals low air, like a wig wag, light

What's the time limit?

My Mack seems like only 7-8 brake applies drains the tank at idle. I've had the brakes dynamite while moving it in the yard.

 

[Welder Dave]

The air buzzer works. Sometimes goes off around 60 PSI and sometimes at 65+ PSI. I guess it's common to have the purge valve leak a little sometimes?

 

[cuttin edge]

Doesn't need to be a buzzer, just something that signals low air, like a wig wag, light

What's the time limit?

My Mack seems like only 7-8 brake applies drains the tank at idle. I've had the brakes dynamite while moving it in the yard.

No idea the time but here it has to have some type of chime

 

[Deere500a]

Grain of salt DOT v State 60psi or 85 odd -bus low air til cut out 45sec but a rig is 2min

 

[IceHole]

Grain of salt DOT v State 60psi or 85 odd -bus low air til cut out 45sec but a rig is 2min View attachment 361838

Should be doesn't mean MUST BE though.

 

[Truck Shop]

This all depends on how many and volume of tanks in various systems.

 

[cfherrman]

I removed my low air buzzer because of wiring problems, it had a switch on it, and forgot to put it back. It's mobile equipment that drives less than 5,000 miles a year.

I think I'm going to find a old wig wag and put one on, sounds cool too