Wouldn't Build Air:

[Rob]

Yesterday I went to move my R795 and the truck would not build air after idleing for over 20 minutes. Further investigation revealed the air dryer, (Bendix AD-2) was discharging with each stroke of the compressor. I had just rebuilt this unit a few months ago and used everything that was available and all parts were OEM Bendix. I unscrewed the discharge valve carrier from the bottom plate, and took the valve assembly apart. To my surprise, the valve, spring, and seat for the rubber sealing valve were "flash rusted" to the point the valve would not seal. This was a complete surprise as all the parts were new under a year ago, and the truck has only idled for the most part since.

After cleaning up the valve assembly and carrier in the bead blaster, I then lubricated all metal and rubber parts with a silicone gel and reinstalled everything. Although the compressor discharge is much slower than my other trucks, it did reach 120psi and the governor did trip the discharge. A lot of the gel blew out on this first cycle and the air rushes out much louder, and faster now.

I guess that I'm surprised how quickly these parts rusted up without usage. I know the discharge air will not be that hot due to the truck not running at high rpm always, but still less than a year is a little short lived. If something like this would have happened to a vehicle in use it could have been expensive as it made no perceivable air in the tanks to even release the brakes.

Rob