SuiteSuccess Posted July 28, 2015 Report Share Posted July 28, 2015 Replaced my dash air valve without problems. Checked all the connections for leaks with "The Whisper" leak detector and all good. Still have the original "symptom". When I release my park brake (pushing in the yellow knob) it takes about 9 seconds for the air "whoosh" to end. It seems as if it is slow to apply air to my brake cans. When applying the park brake (pulling out the yellow knob ) whoosh is only 1-2 secs. Compared my brake release to two other trucks and mine about 3 secs slower. Can find no leaks and it is same whether pressure 60 psi or 125 psi on gauge. Questions: 1. Could it be a bad brake can or cans? 2. Could a bad air governor have any effect? 3. Is this just normal for my truck? 2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift Bed Build by "JW Morgan's Custom Welding" 2017 DRV 39DBRS3 2013 Smart Passion Coupe "Itty Bitty" "Don't go around saying the world owes you a living. The world owes you nothing. It was here first!" Link to comment Share on other sites More sharing options...
Rick & Alana Posted July 28, 2015 Report Share Posted July 28, 2015 My guess is a quick release valve or the spring brake release valve. The air does not actually have to run all the way back to the push pull valve to exhaust. Here is a link to the Bendix Handbook. You might find your answer here. http://www.suspensionspecialists.com/techinfo/Bendix_Brake_Handbook_2009.pdf Rick and Alana Fulltimers 2018 Newmar Ventana 4037 2020 Jeep Gladiator 1997 Jeep TJ 2009 Mobile Suites 36RSSB3 formerly owned 2000 Volvo 770, 600 Cummins ISX,18 speed autoshift, 14 foot "garage" ET,Jackalopee,MaxBrake,Pressure Pro pro www.rickandalanasgreatadventures.blogspot.com Link to comment Share on other sites More sharing options...
Guest THE TRAILERKING Posted July 28, 2015 Report Share Posted July 28, 2015 When I release my park brake (pushing in the yellow knob) it takes about 9 seconds for the air "whoosh" to end. That's a confusing statement...... When you "Push" the yellow button there shouldn't be a "Whoosh". It's not releasing air from anywhere. It's actually supplying/charging air to the brake pot chambers. When pull the button you should get the fast release "whoosh" of air from the quick release valve near the rear of the truck. Link to comment Share on other sites More sharing options...
SuiteSuccess Posted July 28, 2015 Author Report Share Posted July 28, 2015 That's a confusing statement...... When you "Push" the yellow button there shouldn't be a "Whoosh". It's not releasing air from anywhere. It's actually supplying/charging air to the brake pot chambers. When pull the button you should get the fast release "whoosh" of air from the quick release valve near the rear of the truck. You are right, it is not a whoosh like from the quick release. The best I can explain is when I push the yellow knob I can hear air flow for approximately 9 secs. It does not sound any different than the two trucks I compared (Steve Dixon's and Raymond Church) just took longer for the sound to become inaudible. Their's both took about 5-6 secs. Maybe this is just normal for my truck. Brakes release fine at the end of that time. Since I use to fly a lot privately, I am always listening for things that sound "different" than what I think they should. May try to make a short video and attach if I can figure how. 2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift Bed Build by "JW Morgan's Custom Welding" 2017 DRV 39DBRS3 2013 Smart Passion Coupe "Itty Bitty" "Don't go around saying the world owes you a living. The world owes you nothing. It was here first!" Link to comment Share on other sites More sharing options...
Guest THE TRAILERKING Posted July 28, 2015 Report Share Posted July 28, 2015 I don't think there's anything wrong the way you say yours is operating. Your truck is a tandem.......The others you are comparing, are they tandem or single axle? Not all are the same in comparison. Link to comment Share on other sites More sharing options...
SuiteSuccess Posted July 28, 2015 Author Report Share Posted July 28, 2015 I don't think there's anything wrong the way you say yours is operating. Your truck is a tandem.......The others you are comparing, are they tandem or single axle? Not all are the same in comparison. One tandem and one singled. Probably normal for my truck. I'll compare some more at the National Rally. How can you tell if you have a bad brake can? Will it not release? BTW thanks for the help. 2006 Volvo 780 "Hoss" Volvo D12, 465hp, 1650 ft/lbs tq., ultrashift Bed Build by "JW Morgan's Custom Welding" 2017 DRV 39DBRS3 2013 Smart Passion Coupe "Itty Bitty" "Don't go around saying the world owes you a living. The world owes you nothing. It was here first!" Link to comment Share on other sites More sharing options...
Guest THE TRAILERKING Posted July 28, 2015 Report Share Posted July 28, 2015 How can you tell if you have a bad brake can? With a bad air pot it can be an external leak, internal, or both. **NEVER ATTEMPT TO TAKE ONE APART......If you are not familiar with them. The park brake spring is under tremendous compression. They can take your head off and KILL you. The older ones had the spring-side chamber bolt/clamped together but all the new ones are factory crimped (non serviceable). (#1) Internally can have a leaking o-ring on the park brake actuator push rod. If that happens the service brake will apply when push the yellow button. (#2) Externally will have air leaking if a "park brake" or "service brake" rubber diaphram is cracked/deteriorated. (when pushing yellow button or treddle valve for service brake) Link to comment Share on other sites More sharing options...
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