doublewide
Senior Member
Last week I noticed a problem with the air brake system on my 1988 Ford F800. I had been using the truck by itself daily during the week and all systems were working as designed. When I connected my trailer to move my dozer is when the problem became apparent.
Problem; Setting the parking brakes (pulling the yellow dash mounted knob out), results in what sounds like a large volume of air either passing through the dash mounted control valve or exhausting from it. At the same time air exhausts from one of the two quick release valves at the rear of the truck. In addition, the same sound of a large amount of air passing through the tank mounted relay on the trailer can be heard. This air flow slows and eventually stops. During this time, the dash mounted air pressure gauge does not show any change in pressure. If I release the parking brakes, once again, I hear a large amount of air flowing through the control valve, the pressure gauge shows a drop in pressure till the governor reaches the cut in pressure, system pressure builds till the trailer tank is full and then all returns to normal.
Problem; Setting the parking brakes (pulling the yellow dash mounted knob out), results in what sounds like a large volume of air either passing through the dash mounted control valve or exhausting from it. At the same time air exhausts from one of the two quick release valves at the rear of the truck. In addition, the same sound of a large amount of air passing through the tank mounted relay on the trailer can be heard. This air flow slows and eventually stops. During this time, the dash mounted air pressure gauge does not show any change in pressure. If I release the parking brakes, once again, I hear a large amount of air flowing through the control valve, the pressure gauge shows a drop in pressure till the governor reaches the cut in pressure, system pressure builds till the trailer tank is full and then all returns to normal.