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Old 01-04-2018, 05:42 PM   #1
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Air compressure

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

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Old 01-04-2018, 05:46 PM   #2
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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

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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.

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Old 01-04-2018, 05:48 PM   #3
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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.

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Old 01-04-2018, 05:51 PM   #4
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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.

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Old 01-04-2018, 05:52 PM   #5
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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.

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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

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Old 01-04-2018, 05:55 PM   #6
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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
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

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Old 01-04-2018, 06:00 PM   #7
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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

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Good luck. Where are you at?

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Old 01-04-2018, 06:01 PM   #8
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Yes, somewhere warm, inside and that things out, must be moisture involved in the system.

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Old 01-04-2018, 06:02 PM   #9
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Good luck. Where are you at?

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St. Louis. South city

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Old 01-04-2018, 06:03 PM   #10
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St. Louis. South city

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It isn't much warmer out here in New England. Single digits tonight and negative for the next few days

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Old 01-04-2018, 06:06 PM   #11
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It isn't much warmer out here in New England. Single digits tonight and negative for the next few days

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I hope it's not the compressor. It's in a tricky spot.

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Old 01-04-2018, 06:07 PM   #12
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Yes, somewhere warm, inside and that things out, must be moisture involved in the system.

John
It's idling really rough all of a sudden too

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Old 01-04-2018, 06:40 PM   #13
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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.
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Old 01-04-2018, 07:16 PM   #14
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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.
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.

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Old 01-04-2018, 07:18 PM   #15
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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.

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You drain water from the bottom of the filter, normally.
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Old 01-04-2018, 07:19 PM   #16
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You drain water from the bottom of the filter, normally.
Oh

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Old 01-04-2018, 10:08 PM   #17
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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.

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Old 01-04-2018, 10:23 PM   #18
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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.
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Old 01-08-2018, 09:50 PM   #19
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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.

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Old 01-08-2018, 11:06 PM   #20
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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.
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