martysantic Report post Posted August 5 2017 Berkshire Class A. Seems like it is taking longer and longer for the air pressure system to fill the air bags and for the pop off valve to pop, even at fast idle. In fact on the last start I got near max pressure and the pop off valve never opened. It took a short drive to get to the max pressure. Is there a spec on how long it should take to pressurize to max/normal pressure? Called Freightliner and they said call Cummings, called Cummings and they said it is a Freightliner issue. Any suggestions I should have the techs look at during next service visit would be appreciated. Share this post Link to post Share on other sites
desertdeals69 Report post Posted August 5 change the filter on the drier. Share this post Link to post Share on other sites
desertdeals69 Report post Posted August 17 Hello, I am testing to see if my profile updated after I made a change earlier today. Share this post Link to post Share on other sites
rayin Report post Posted August 18 (edited) It's not a pop-off valve, it is the purge valve. The purge valve works in conjunction with the filter/desiccant dryer. The filter should be replaced every 3-4 years for a MH. The filter removes water and oil mist from compressed air. If said moisture and oil mist get into the compressed air ttanks it must be drained out or it will work its way into the air brakes and likely cause expensive problems. Most any auto supplies store sells new filters, as well as HDT repair shops. Follow installation directions exactly when replacing the filter, any dirt introduced into the filter housing will cause problems in the future. Edited August 18 by rayin Share this post Link to post Share on other sites
