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Grizzly · 10-07-2017, **(Subject: Air Compressor ?? )**

Most nights I lose all my air. I have yet to hear an audible leak and other nights I might only lose half my air. However lately I've had trouble building air idling with the pto kicked up. I thought it was the air system on the trailers I use robbing me of air but it does it when I'm unhooked too. Some mornings or given enough time it will build air. Others it won't start to build air until kick the rpms up to 1200. Once I start driving its ok. If I stop and set the brakes on the trailer or tractor, either or, or both I will drop pressure. Like when sliding tandems and you have to set/release them a couple of times. Rev it up, build the pressure back up and good to go. Doesn't lose sitting at a light either. Just over night and trying to drop and hook or slide tandems.
Am I missing an air leak somewhere?
Is my compressor going bad and need replaced?
Something clogged I don't know about?
This? that? the other?

Brock · 10-07-2017, **(Subject: Air Compressor ?? )**

Possible that the main supply line from the compressor to the air dryer is rubbed through.

Use the KISS method. Keep it simple stupid.

Buy a grab a squirt bottle and dish soap and water and spray everywhere. Lift your air suspension cause the airbags crack where they fold back in at the very bottom of the airbag so you don't see te cracking or hear it till the bag lifts.

Rawze · 10-07-2017, **(Subject: Air Compressor ?? )**

The air bags on the back of the cab are known for making the air go down if it is windy outside or if your are shaking around in the cab a lot.

Soapy water on all the fittings and solenoid blocks is your best bet otherwise.

Waterloo · 10-07-2017, **(Subject: Air Compressor ?? )**

I have been chasing a leak like that for years on this ProStar of mine. Had it in a few shops that were dead silent and went nuts with the soapy water and spray bottles a few times. Never found it, only other place would be behind the dash somewhere is all I can figure, but have never found anything there either when having the dash apart. I just replaced both cab air bags, that seemed to help, but still losing air somewhere. Good luck!

Grizzly · 10-07-2017, **(Subject: Air Compressor ?? )**

Ok so the only leak I've located is on the leveler valve at the rear. I have sprayed everything I could see and get to as much as I can. This is the only thing I've spotted and after an hour or so of letting it set it is still leaking just the smallest leak, but I guess its enough and with a trailer on, probably more.
However this still doesnt, at least in my mind, explain why I have rev the motor up to 1400 rpm to get it to start filling with air.

Wiseman · 10-07-2017, **(Subject: Air Compressor ?? )**

(10-07-2017 )Grizzly Wrote: However this still doesnt, at least in my mind, explain why I have rev the motor up to 1400 rpm to get it to start filling with air.

This is most likely related to :
1. Bad air compressor governor (really cheap $ )
2. Sticky plunger (controlling the moving valve)inside air compressor head . (Usually caused from soot buildup)

First (and easiest) : engine off
Pull off the 1/4" hose (usually blue color) off air compressor and spray liberally with WD-40. Do the same on the intake of the compressor head too.
Connect it back and start the engine. Let it build air and go off a few times.
Repeat all over again .
If you see improvement , then you'll know air compressor head need replacement .
If no improvement is seen , replace governor .

Be sure your air dryer works properly.

Waterloo · 10-07-2017, **(Subject: Air Compressor ?? )**

And throw a new D'thingy filter on the Air Dryer.... ;-)

Hammerhead · 10-08-2017, **(Subject: Air Compressor ?? )**

(10-07-2017 )Wiseman Wrote: This is most likely related to :
1. Bad air compressor governor (really cheap $ )
2. Sticky plunger (controlling the moving valve)inside air compressor head . (Usually caused from soot buildup)

First (and easiest) : engine off
Pull off the 1/4" hose (usually blue color) off air compressor and spray liberally with WD-40. Do the same on the intake of the compressor head too.
Connect it back and start the engine. Let it build air and go off a few times.
Repeat all over again .
If you see improvement , then you'll know air compressor head need replacement .
If no improvement is seen , replace governor .

Be sure your air dryer works properly.

Instead of WD-40, I suggest using Air Tool Oil.
At least if some gets by the air dryer it is formulated to be used in air tools so it won't have anything that may potentially eat at o-rings, valves, sensors, etc and will actually lubricate them a little.

Rawze · 10-08-2017, **(Subject: Air Compressor ?? )**

(10-08-2017 )Hammerhead Wrote: Instead of WD-40, I suggest using Air Tool Oil.
At least if some gets by the air dryer it is formulated to be used in air tools so it won't have anything that may potentially eat at o-rings, valves, sensors, etc and will actually lubricate them a little.

That or a bit of 3-in-1 oil perhaps if you can't find air-tool oil handy? - Very similar.

I think the 'wd-40' thing is from an old cummins bulletin about the compressor head getting sooty and sticking if I am not mistaken. i thought it odd back then to recommend that stuff too, as it is a terrible lubricant, and prone to hardening seals and deteriorating plastic air lines. I had completely forgotten about that, thanks for bringing it up again.