Heading to Ft Stockton to do timing for the BBORR. (Big Bend Open Road Race). I have been having a loss of air pressure that is getting steadily worse. Before, I could leave the coach for days and the pressure would not go down more then 10 lbs or so.

Now (both front and rear air)it will go down to zero in 3-4 hours or so. Again this has not been an abrupt change, a year ago it would go to zero and it would take about a day.

It is definitely going down faster now. I have used dish washing liquid and sprayed all the air connections up front, around the supply tank by the front axle and around the dryer in the rear. I have had wifey go around and listen, can't find it. The only area I could not spray is around the air input to the foot brake peddle.

The air on my coach is only used for air brakes (air over hydraulic) nothing else. I don't have air suspension, or use the air for cruise control or dash HVAC vacuum.

Anybody got any ideas where to look?

Air Gov - Dryer - are 2 areas to check.

If the check valve going into the airdryer becomes defective, it'll back feed up the line and vent into the compressor and then into the intake manifold... you'll never hear that.

Thanks Bill, I have been a bit worried about the dryer as I haven't serviced it in awhile.

I FOUND IT!!

It is one of the pressure switches that turns on the warning lights. I guess last time when I used detergent, I didn't get enough on it, this time it really bubbled there and now I can hear it if I get my deaf ear close enough. I will post pictures later when I have faster internet connection

I am in Socorro NM now and hope I can find a parts store open, at least I know what it is and will be an easy fix.

This switch is normally closed and will open at about 60 lbs.

Thanks again Bill.

I would like to add that I have two addition air uses. The front vacuum generator that powers the heater controls and the rear vacuum generator that provides vacuum for my cruise control.

quote:

Originally posted by MWrench:
This switch is normally closed and will open at about 60 lbs.

This is your "Low Air Psi" Warning Light and Or Buzzer.

I have temporarily taken the switch out and plugged the hole. Being Sunday, I could not find a replacement switch. I still have another leak some where but at least now it is VERY slow and only went down to 80 lbs over night.

I will replace both switches when I find the suitable replacement.

Gary: I took out the air powered vacuum generators a long time ago, I use a motorized vacuum pump for the front HVAC and adapted an all electronic cruise cruise control unit from a GMC late model truck.