mysterious air leak
2003 Discovery 39s. When driving the air pressure in the front tank cycles from 120psi to 95psi and back every 15 seconds. Sitting still with engine running air pressure is steady at 120psi. Rear ai...
Forum Discussion
I am not sure what you are referencing for your system description but it is incorrect.
The first reservoir after the compressor/air dryer is the "supply" or sometimes called the "wet" tank. From there it feeds each of the two brake reservoirs through check valves. The rear axle brake reservoir is the "primary" reservoir because the rear axle does most of the braking. The front axle reservoir is the "secondary" reservoir.
The tank pressure is not controlled by pop off valves. It is controlled by the air governor. Turns on the compressor when the air falls below about 90 psi. Turns off the compressor when the pressure goes to around 120 PSI.
There is a system relief valve that pops off if there is a malfunction of the system causing it to overpressurize. That is usually around 140 psi.
The first reservoir after the compressor/air dryer is the "supply" or sometimes called the "wet" tank. From there it feeds each of the two brake reservoirs through check valves. The rear axle brake reservoir is the "primary" reservoir because the rear axle does most of the braking. The front axle reservoir is the "secondary" reservoir.
The tank pressure is not controlled by pop off valves. It is controlled by the air governor. Turns on the compressor when the air falls below about 90 psi. Turns off the compressor when the pressure goes to around 120 PSI.
There is a system relief valve that pops off if there is a malfunction of the system causing it to overpressurize. That is usually around 140 psi.
