Full Floater Posted March 5, 2023 Share Posted March 5, 2023 Installed a new Bendix E3 foot valve on my 75 R600. Now it leaks from the exhaust port of the foot valve when the parking brakes are APPLIED. Next to no leakage when released. Is this an indication of something backfeeding into the foot valve when it's not supposed to? I didn't have this problem with the old foot valve that was replaced, BUT; I did do a pile of air line and air system replacement work all at the same time so there's a chance that something somewhere has changed or been messed up. Just thought id ask here before I tear into it all again. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/ Share on other sites More sharing options...
mechohaulic Posted March 6, 2023 Share Posted March 6, 2023 i'll go with a line (or two) crossed. why was the foot valve changed in the first place ??? . is this a tractor :: trolley valve and double check valve system for trailer or straight truck (dump , etc)? photo looks to be a R or superliner, bad eyes can't tell. would the photo be truck in question ??? Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526625 Share on other sites More sharing options...
Full Floater Posted March 6, 2023 Author Share Posted March 6, 2023 No the profile pic truck is a different truck. But it's similar. The foot valve was changed as I had the engine out and it was accessible and original as far as I could tell. I wanted to replace it while it was easy to get to. Matched all the lines as they came off the old one. Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526632 Share on other sites More sharing options...
Hayseed Posted March 6, 2023 Share Posted March 6, 2023 2 hours ago, mechohaulic said: i'll go with a line (or two) crossed Me Too.. 1 Quote "Be who you are and say what you feel...Because those that matter...don't mind...And those that mind....don't matter." - Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526637 Share on other sites More sharing options...
mechohaulic Posted March 6, 2023 Share Posted March 6, 2023 based on possibility everything went back together correctly ,no lines crossed the original valves was working properly ; now there is an issue+ faulty new valve. ?? heck of a gamble with new parts in all fields today. Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526646 Share on other sites More sharing options...
Full Floater Posted March 6, 2023 Author Share Posted March 6, 2023 4 hours ago, mechohaulic said: based on possibility everything went back together correctly ,no lines crossed the original valves was working properly ; now there is an issue+ faulty new valve. ?? heck of a gamble with new parts in all fields today. Yup, parts quality control sure took a turn for the worst. Well im going thru things slowly and at least im learning exactly what lines go where and what ports do what.....so I guess that's a plus 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526664 Share on other sites More sharing options...
mechohaulic Posted March 7, 2023 Share Posted March 7, 2023 self taught knowledge many times has a longer lasting effect than knowledge of a book or instructor. i don't remember (lot of things) if the top half of foot valve is supply / lower section is delivery. should be . does this unit in question have the trolley valve hooked to rear brakes. picture looks to be straight chassis /tanker. don't figure a connection between applied parking brake and treddle valve air leak. parking brakes function proper??? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526698 Share on other sites More sharing options...
Full Floater Posted March 8, 2023 Author Share Posted March 8, 2023 Parking brake does function properly and brakes apply properly. Today I discovered that its backfeeding into a supply port of the foot valve (causing it to exit out the exhaust port), from the front brake limiting valve on the dash, which is fed from the parking brake valve.... Still haven't "fixed" anything yet, but that's going on it seems. It does have a trolley valve/trailer brake valve. The position of the lever has no effect on the situation, but that's as far as I got with that Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526736 Share on other sites More sharing options...
mechohaulic Posted March 8, 2023 Share Posted March 8, 2023 with that info;;I go back to a line crossed on brake valve. wasn't leaking previously to new valve install. don't understand why the front axle brakes are connected to parking brake valve.??? fronts are service only . with the elimination of front axle limiting vale in todays new units, air to front brakes comes from foot operated valve. (short version). the limiting valve back then went from foot valve to dash valve to front brakes, 2 Quote Link to comment https://www.bigmacktrucks.com/topic/72569-foot-valve-exhaust-port-leak/#findComment-526758 Share on other sites More sharing options...
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