trying to find out why my drier pops off about every 15-20 seconds when driving at hyway speeds.  the red needle on guage you can watch it drop pretty quick as you drive and builds right back up and drier pops off. Only does it when driving not whem pumping truck is a 93 already had regulator on pump replaced and new dryer.  any advice or ideas.  32 meter putz mounted on mack mr.

Check your airline going to your regulator for a hole, had the same problem the plastic line rubbed a pin hole in it.

I also have a 93 Mack. My compressor is leaking oil into the air system and when the drier filter fills up it cycles like you are describing. A new filter fixes it for 6 to 8 months. When you park and pump does oil build up on the ground under the drier? I know the correct fix is a new compressor or .....hope things pick up in 2013 :)

MVCP is right, when you do change the compressor, be sure to change the stainless steel line coming directly out of the compressor; you also need to change your dryer cartridge

Chock wheels,shut off engine,chock wheels,release brake,listen

Drier should pop (sneeze) when the compressor hits max pressure and stops putting out air.  If you are loosing pressure while driving and not while pumping I would have to say that you have a leak in your brakes when the maxi's are released or a leak in your air system that shifts you pto.

The fix for now was to put a shutoff valve on airline going the boom valves.  rebuild kits for air actuators didnt fix the leaking valves so will have to replace or find different actuators, not electric/air actuators. just have to remember to turn valve back on after folding outriggers out or boom doesnt work.