Mystery Air Solenoid. Leaking up front. 2007 Knight.

[TDaleABQ]

Hello Folks,

I have a 2007 Monaco Knight. Today when I started the coach up, there was an air leak near the generator. I have attached a picture and a short video. Soon as I turn the key on and 12 volts gets to this it starts hissing.  I have owned this coach 2007 and have never heard this before. I am at a RV resort in Oregon and the coach is up on jacks if that means something. If someone knows what this is I would appreciate it. Thanks so much  

Tim

[Ivan K]

Looks like a dump valve to me, either your switch or the valve are stuck on dumping air.

[Tom Cherry]

3 minutes ago, Ivan K said:

Looks like a dump valve to me, either your switch or the valve are stuck on dumping air.

Good observation.  Tim, this is a solenoid valve on a hard plumbed Air Line.  The two wires control the opening and closing of the valve.  Assume you have the manual.  Start reading around page  186.  There is a detailed description of the air system and the required owner maintenance.  If you have not been draining or purging the air as recommended, then there could be an issue with the valve.  Read and look at the pictures.  Drain all the air per the manual.  Then take a large screwdriver or one that has a good sizes handle.  Tap, rather aggressively on the body of the valve.  Not like trying to drive a nail, but to see if there is something lodged in it.  Then close all the air drains and restart the MH to get the pressure back up.  If the valve is still leaking, chase the wiring on the solenoid back to a connector snd disconnect the power from the solenoid.

Past that, call a tech….one that isi familiar with the air system.

[TDaleABQ]

Thanks Tom. I took the coach off the levelers and the two above the air dryer started leaking as well. Once I put the coach back on the levelers the two in the rear stop hissing but the one in the front continues to leak. It will not build up pressure with the jacks down?   Where should I look for the solonoids. Thanks 

[Ivan K]

Before you go replacing them, touch them if they feel warm, as if current was flowing through them or pinch the wires for voltage, assuming that what ever switch you use to open them is OFF. Hard to believe that all 3 would just quit in open position at the same time. I thought that dump switch was ment to be momentary but know some people wedge them to stay ON. 

[TDaleABQ]

Mystery solved. Spoke with a friend back home and just like you said. The dump switch was stuck on. What a dummy. Thanks for all the replies. 

[TomV48]

6 hours ago, Tom Cherry said:

Good observation.  Tim, this is a solenoid valve on a hard plumbed Air Line.  The two wires control the opening and closing of the valve.  Assume you have the manual.  Start reading around page  186.  There is a detailed description of the air system and the required owner maintenance.  If you have not been draining or purging the air as recommended, then there could be an issue with the valve.  Read and look at the pictures.  Drain all the air per the manual.  Then take a large screwdriver or one that has a good sizes handle.  Tap, rather aggressively on the body of the valve.  Not like trying to drive a nail, but to see if there is something lodged in it.  Then close all the air drains and restart the MH to get the pressure back up.  If the valve is still leaking, chase the wiring on the solenoid back to a connector snd disconnect the power from the solenoid.

Past that, call a tech….one that isi familiar with the air system.

Probably a diesel truck service would be more generally knowledgeable on air brakes