Sudden 20-30 Pound Air Pressure Drop

[Archie T. Hogan]

When driving, the pressure suddenly drops 20-30 pounds, with no brakes being applied, nor nothing that I can think of that is air operated being operated (cruise, step, waste dump valves), does this mean that there is a leak somewhere?

Archie

[77newell]

Archie: one inference of your statement I would like to confirm is the the 20-30 psi drop is happening repetitively with periods of normal pressure in between. If that is the case it is highly likely it is an electrical issue with the pressure reporting gauge system. Actually, come to think of it, if you had this drop instantaneously there is no way a leak large enough to make that happen would stop at 20-30 psi. In addition your compressor would be running constantly and when you stop outside you would hear air leaking from somewhere.

[Archie T. Hogan]

Yes that is correct. It happens with periods of normal pressure in between.

[GringoPhil]

If the governor is staying in bypass too long the pressure would drop, then when it kicks in it would rise up again.

[77newell]

Archie: when you say the pressure suddenly drops I hear you saying that the pressure is dropping in seconds rather than at the usual bleed-down rate when traveling which would take 10 minutes or more to drop that much. Basically, I'm trying to figure out what the relationship is or isn't to the normal pressure bleed-down and rebuild cycle. If the pressure stays up and then suddenly drops but immediately starts to rebuild I would guess the the pressure sensor is sticking. If the pressure is dropping normally but then suddenly drops and then suddenly rises I would guess the sensor electrical ground in intermittent. If it is dropping gradually beyond the normal kick-in point to recharge then I would be where GringoPhil is. The source of your problem will be pinpointed by the pattern of the ups and downs.

[folivier]

Is this the brakes system pressure dropping, or the coach systems, or both?

[Archie T. Hogan]

If the pressure stays up and then suddenly drops but immediately starts to rebuild I would guess the the pressure sensor is sticking. If the pressure is dropping normally but then suddenly drops and then suddenly rises I would guess the sensor electrical ground in intermittent. If it is dropping gradually beyond the normal kick-in point to recharge then I would be where GringoPhil is. The source of your problem will be pinpointed by the pattern of the ups and downs.

Precisely whats going on. Gauge is reading normal than registers between 20-30 pounds loss, builds normal again and repeats cycle.