Air compressure

Dead pirate

Dead pirate

Senior Member
Joined
Feb 24, 2016
Posts
529
Location
in the bus on the road
How do i check to see if the air compressor is out verses an air leak? I don't hear any leak but i lost 10 lbs everytime i hit the brakes

Sent from my LG-LS777 using Tapatalk
 
Dead pirate said:
How do i check to see if the air compressor is out verses an air leak? I don't hear any leak but i lost 10 lbs everytime i hit the brakes

Sent from my LG-LS777 using Tapatalk
Click to expand...
If your compressor is not working at all, you will never build air pressure.
If you have air pressure, but use it faster than you can build it... Then you may have an air leak or your compressor is going bad.
Only way I know to check for an air leak would be to let the system build full pressure, turn off the engine, and them listen/spray soapy water on all the air lines.
There are ways to check the compressor, but I am not well versed.

Sent from my XT1254 using Tapatalk
 
Plus, every time you press the brakes, you will use air. The compressor will have a low pressure cut in and a high pressure cut out.
So it will charge to say 110psi, then as the air is used it will bleed down to 85psi before the compressor cuts in.

Sent from my XT1254 using Tapatalk
 
Are there any valves right after the compressor to close the outgoing lines. Close if any and let compressor run till it shuts itself off at working pressure or runs steady. If it runs steady then it's not working or bad pressure switch likely.

John
 
Njsurf73 said:
Plus, every time you press the brakes, you will use air. The compressor will have a low pressure cut in and a high pressure cut out.
So it will charge to say 110psi, then as the air is used it will bleed down to 85psi before the compressor cuts in.

Sent from my XT1254 using Tapatalk
Click to expand...
I can't tell if it's going bad but i think it is. It has been staying at 60, but i got it to move and it dropped to 20 and locked up. Now our doesn't want to charge

Sent from my LG-LS777 using Tapatalk
 
BlackJohn said:
Are there any valves right after the compressor to close the outgoing lines. Close if any and let compressor run till it shuts itself off at working pressure or runs steady. If it runs steady then it's not working or bad pressure switch likely.

John
Click to expand...
I think it's this cold. Ill check for the valves in the morning. I could put a tie in and fill the tank with a portable. Then i could get somewhere to really look at it

Sent from my LG-LS777 using Tapatalk
 
Dead pirate said:
I can't tell if it's going bad but i think it is. It has been staying at 60, but i got it to move and it dropped to 20 and locked up. Now our doesn't want to charge

Sent from my LG-LS777 using Tapatalk
Click to expand...
Good luck. Where are you at?

Sent from my XT1254 using Tapatalk
 
Water in the fuel, and in the air system would explain both those symptoms.

Let it warm up a bit. Drain any water from the fuel system and maybe change the fuel filter.

See if the engine can build air-pressure when it's a bit warmer and nothing is frozen. It should build and hold 120+ psi, and it shouldn't lose 10 psi when you hit the brakes.

If the system does build pressure, you will hear any major leaks when you shut of the engine. Even small leaks make quite a noise. Leaks that can only be detected with soapy water will not throw those symptoms. They would show as the system leaking down more quickly than it should.
 
Twigg said:
Water in the fuel, and in the air system would explain both those symptoms.

Let it warm up a bit. Drain any water from the fuel system and maybe change the fuel filter.

See if the engine can build air-pressure when it's a bit warmer and nothing is frozen. It should build and hold 120+ psi, and it shouldn't lose 10 psi when you hit the brakes.

If the system does build pressure, you will hear any major leaks when you shut of the engine. Even small leaks make quite a noise. Leaks that can only be detected with soapy water will not throw those symptoms. They would show as the system leaking down more quickly than it should.
Click to expand...
I'm going to change the fuel filter. How do i drain water from the fuel? I'm going to hit the air lines with a heat gun and blow the lines out. I'm almost sure it's a water issue now.

Sent from my LG-LS777 using Tapatalk
 
Dead pirate said:
I'm going to change the fuel filter. How do i drain water from the fuel? I'm going to hit the air lines with a heat gun and blow the lines out. I'm almost sure it's a water issue now.

Sent from my LG-LS777 using Tapatalk
Click to expand...

You drain water from the bottom of the filter, normally.
 
You should be doing a DOT air brake test before each trip, and that will quickly tell you if it's OK or not. If it's not OK, you shouldn't be driving it at all until it's fixed. And drain those air tanks daily!

If you have water in the fuel tank you need to crack open the drain plug under the tank until only clean diesel comes out. Then replace the filters and/or drain the Racor separator. Water will do Very Bad Things to injectors, which in turn can cause major damage to pistons and valves. It's also not too good for injector pumps.

John
 
Last edited:
One of the most common fails is the air compressor governor, they are cheap and usually easy to replace. Napa should have one. I would start there.
 
So final assessment: the air drier failed. Probably when it froze. Water build up in the line and the cold snap finished it off. It finally got up to 40 and it thawed. It charges up to 130. It still loses 10 psi every time i step on the brakes. If i do it in rapid succession it will drop quite a bit.

Sent from my LG-LS777 using Tapatalk
 
Just for clarification it was the failed air dryer that was bleeding off your pressure?

I've been following along, like a couple hundred other people. Feeling your pain with this.
 
You must log in or register to reply here.

Similar threads

TH
Seeking bus driver tutoring lessons
kromboy
KR
Drewser
Air gauges show full, parking brake doesn't pop, still low air
Drewser
Drewser
SU
Hi all! New to skoolies, need some education! :)
nikitis
nikitis
SU
For sale! 1987 Wanderlodge PT36 Detroit 6v92ta Turbo runs and drives needs love $12k
nikitis
nikitis
Drewser
Blue Bird RE with Rear Air - get working or remove?
nikitis
nikitis

New posts

Try RV LIFE Pro Free for 7 Days

  • New Ad-Free experience on this RV LIFE Community.
  • Plan the best RV Safe travel with RV LIFE Trip Wizard.
  • Navigate with our RV Safe GPS mobile app.
  • and much more...
Try RV LIFE Pro Today
Back
Top