Refined Trucker Posted December 14, 2015 Share Posted December 14, 2015 01 CX when air pressure drops to cut in level air starts hissing from dryer for sometimes 2 minutes or more then stops and pressure builds as normal. During this the pressure holds constant but noticed if I'm building a lot of boost during this time hissing gets much louder. Just wandering which end to look at first compressor govner or dryer. Quote Link to comment https://www.bigmacktrucks.com/topic/43097-dryer-hiss/ Share on other sites More sharing options...
Jnicol6600 Posted December 14, 2015 Share Posted December 14, 2015 I cant help you but i have a peterbilt that does the same thing. Hope you get some good answers. Ive been close to buying a new dryer. Mine has a new governor. Quote Link to comment https://www.bigmacktrucks.com/topic/43097-dryer-hiss/#findComment-315729 Share on other sites More sharing options...
turckster Posted December 15, 2015 Share Posted December 15, 2015 My first thought is worn o-rings in the purge valve. Sounds like the purge valve is hanging open, a renew/rebuild kit would most likely solve that issue. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/43097-dryer-hiss/#findComment-315784 Share on other sites More sharing options...
Refined Trucker Posted December 19, 2015 Author Share Posted December 19, 2015 Thanks will try the dryer first. Quote Link to comment https://www.bigmacktrucks.com/topic/43097-dryer-hiss/#findComment-316336 Share on other sites More sharing options...
farmer52 Posted December 19, 2015 Share Posted December 19, 2015 When you hear the "hissing", check to see if it is coming from the dryer. Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/43097-dryer-hiss/#findComment-316339 Share on other sites More sharing options...
SuperlinerShane Posted January 25, 2016 Share Posted January 25, 2016 I have had similar problems. It never really gave any problems but I replaced the governor because it's the cheapest place to start. Still did it so I took my ad-4 air dryer off and replaced it with an ad-9 dryer and it stopped it. It could also be as simple as the relief valve on the bottom of the drier sticking open. Hope this helps. Quote Link to comment https://www.bigmacktrucks.com/topic/43097-dryer-hiss/#findComment-321513 Share on other sites More sharing options...
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