Losing Air

It could be leaking parking brake can.. Get out and listen..

 

It's hard to hear an air leak over the Internet.

 

Is this with trailer attached or bobtail?

Has he done the air brake leakdown test?

Has he chocked the wheels, engine off, released the brakes, and listened, looked for a air leak? If leak is not internal of a part, windex works well if you can't find the source of the sound. Spray windex at sound and your leak should become visable.

From your description, he should have put himself OOS, so probably going to a repair facility would be best.

 

My air leak is coming from the black cap in the photo (the nice clean black thing in the midst of the dirt). Little research on air diagrams and it's labeled as governor.. Starts leaking at 50 PSI, and when trailer is supplied it will only build pressure to 65-70 psi and then sits.. You can hear air passing through the trailer supply valve in the cab... Can I adjust or do I sit and wait for repair guy? Road rescue wanted me to drive to Petro 30 miles down the road, but where the leak is I can't imagine the brakes are fully releasing or operating well if, at all. They are "sending someone". But if I can go to them I'd be slightly happier. Yesterday, it seemed ok and built pressure fine, but towards the end of the trip (last 100 miles or so) it felt the load got heavier and my MPG dropped 2 mpg down to a 6. At first, I attributed it to the mountains I was pulling, but now I am not so sure.. I normally stay pretty high.

 

http://www.thetruckersreport.com/truckingindustryforum/customprofilepics/profilepic130092_2.gif

Guess this might help.. Accidentally posted question to Volvo forum.. Apologies!

 

Seems like it's freezing.

 

That's the quick release relay for your park brakes. It should only discharge air when the park brake is initially set.

 

Dump a bottle of dry gas or air line antifreeze into your trailer supply line. If its freezing that will solve it, if not, you need a new valve.