Air Pressure Drops When Ignition OFF

Lay on your back underneath & go looking for it. If possible. A leak is usually audible in a quiet environment.

Never driven an International tho.... Blessed be me! So I can't say if this is 'normal'.... Even if it were, I wouldn't like it.

And is it the tractor losing pressure (primary) or the trailer (secondary)? Sometimes its as simple as a bad glad-hand rubber. Sometimes its not as easy.

Are you hauling the same trailer daily?

Quick test: Next time you park - only set the tractor brakes. Time any secondary pressure drop. This is also good practice for the approaching winter. Frozen trailer brakes you didn't drag to heat up a bit before parking are going to be dragged flat-spotted tires later the next morning.

 

Next time you go to Home Depot, get a 99 cent spray bottle. Fill it with soapy water and next time you can spray all the fittings and hoses to see if you can find the leak. Might take a few tries.
Once you gind the leak the mechanic can fix it.

 

@KillingTime

 

That's how you should park all the time. The trailer brake is not for parking. It even says so on the button.

 

Same here.

I guess teasing does not come across very well online unless I go the extra mile and put //teasing or something at the end of the post... like I do sometimes when I tease about something in which it could go really bad fast.

 

In my time you are supposed to have zero pressure in the mornings. It was a required behavior to open the air tank valves and allow them to drain towards morning. Especially on trucks without a air dryer.

 

Most everyone sets both. You hear it all the time. Big 'psssssh'; little 'pssssssh' a second later.

I only set them both loading / unloading or loaded and parked on an incline.

But I roll with a tank (100k).... So don't trust me. I barely back up anymore. Lol.

 

No that isn't normal for a prostar i had the misfortune to drive one for a couple months. It never leaked down like that.