Highroadhauling Posted August 17, 2023 Share Posted August 17, 2023 I have a 1990 E6-350 in an RD688S. Heard an air leak Monday from relay valve when brakes or trolley handle was applied. Also heard a leak from foot valve, replaced foot valve and relay, relay still would purge air anytime brakes were applied. Brakes continue going soft when loaded, feels like they are at only about 50%. Traced air lines back and no twists or kinks. Drained air tanks, then slowly started going through the system post relay, took old relay apart, it didn't look bad, not sure if anyone has had this problem? Quote Link to comment https://www.bigmacktrucks.com/topic/73180-spongysoft-brakes-purging-relay-valve/ Share on other sites More sharing options...
Popular Post Joey Mack Posted August 17, 2023 Popular Post Share Posted August 17, 2023 Do you have a bad maxi brake chamber 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73180-spongysoft-brakes-purging-relay-valve/#findComment-537152 Share on other sites More sharing options...
doubleclutchinweasel Posted August 17, 2023 Share Posted August 17, 2023 Sounds like it. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/73180-spongysoft-brakes-purging-relay-valve/#findComment-537171 Share on other sites More sharing options...
Highroadhauling Posted August 17, 2023 Author Share Posted August 17, 2023 Doubleclutchinweasel and Joey Mack how would I tell if bad maxi? On the exterior they all look okay Quote Link to comment https://www.bigmacktrucks.com/topic/73180-spongysoft-brakes-purging-relay-valve/#findComment-537223 Share on other sites More sharing options...
doubleclutchinweasel Posted August 17, 2023 Share Posted August 17, 2023 Unhook the parking brake release hose from the cam and apply foot brake. If the can is leaking through, air will come out of the parking brake fitting on the can. Can also do the opposite thing. Unhook the service brake fitting and release the parking brake to see if air comes out the service fitting. Be sure to scotch it securely before trying any of this. Sound reasonable, JoJo? 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/73180-spongysoft-brakes-purging-relay-valve/#findComment-537224 Share on other sites More sharing options...
Joey Mack Posted August 18, 2023 Share Posted August 18, 2023 (edited) I have also chocked the wheels, released the brakes, and with a pair of hose pinch off pliers, would squeeze the lines at each can til I heard the air leak change sound. But if the hoses are in poor shape, your way is better than mine. Mine is just a quickie way Edited August 18, 2023 by Joey Mack Pore cell fone sperring 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73180-spongysoft-brakes-purging-relay-valve/#findComment-537227 Share on other sites More sharing options...
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