OakRidgeMack Posted January 25, 2008 Share Posted January 25, 2008 On the air line that is directly under the cab there is a relay valve i think? When you press the foot pedal air blows out of it? That means that that one is crapped out right? Quote Link to comment https://www.bigmacktrucks.com/topic/3344-relay-valve/ Share on other sites More sharing options...
ThaddeusW Posted January 25, 2008 Share Posted January 25, 2008 Here is a bendix air brake diagram. Its a newer diagram for post 1980 trucks with dual air circuits. If you press down and it blows air out then something is wrong. Is it a broken or leaking hose? Or is it an open port? There is an open port that is the exhaust port. When you take your foot off the brake pedal it exhausts the air pressure out of the system. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/3344-relay-valve/#findComment-16513 Share on other sites More sharing options...
OakRidgeMack Posted January 25, 2008 Author Share Posted January 25, 2008 That open exhaust port doesn't close when you press the pedal...air just leaks out once you press the pedal...that means that the relay valve is no good..right? Quote Link to comment https://www.bigmacktrucks.com/topic/3344-relay-valve/#findComment-16515 Share on other sites More sharing options...
ThaddeusW Posted January 25, 2008 Share Posted January 25, 2008 That open exhaust port doesn't close when you press the pedal...air just leaks out once you press the pedal...that means that the relay valve is no good..right?Correct. When you press down on the brake pedal there shouldn't be any leaks or air coming out of anything. Only when you take your foot off or back off the brake should air be exhausted from the foot valve, quick release valves and relay valves. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/3344-relay-valve/#findComment-16517 Share on other sites More sharing options...
OakRidgeMack Posted January 25, 2008 Author Share Posted January 25, 2008 Thanks Thad....i figured that was what was worng...i wasn't sure but now i am.. thanks alot.. do you happen to know where i can pick up the little piece of metal that connects to the throttle linkage for the idle wire...it is for the idleing control in the cab..it connects right from the wire to the linkage...just a question... Quote Link to comment https://www.bigmacktrucks.com/topic/3344-relay-valve/#findComment-16520 Share on other sites More sharing options...
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