what is acceptable amount of air brake leakdown

[aTX427]

I have a 2008 F650 with air brakes and notice the air brakes will pump the primary system to 120psi, pop off then within a minute or less drop down to 110psi and if left unused overnight will drop down to 90psi. Over a few days time it will go to zero.

The dealer is trying to tell me that the Ford spec states an acceptable amount of pressur loss is 1psi per minute. This does not sound right to me. Does anyone know how much if any the pressure should drop?

[colemen_7.3_IDIturbo]

doesnt sound too far off, i've got kenworths that drop to around 80psi overnight after a day they're empty

[fireguywtc]

Your truck sounds like it has a system better then anything I have ever driven. Your truck seems perfectly normal or better to me.

'Your intial 10 psi or so loss may be due to the tanks cooling off after the fill up and settling in. The pumped air is warm and of course loses a little pressure when the temp goes down.

[alexb]

True. One PSI per minute is the published specification for bleed down with the park brake applied and the service brake released. I wouldn't say there is anything wrong with your truck.