A while back I made a post about the air brakes on the company bucket truck & I tried the foot valve as another member mentioned but it has what seems to be a bypass of air in it also & the brakes won't maintain pressure after popping the park brake off or release the brakes
So you, put your foot on the brake, release the spring brakes and the service brakes don't hold?
-86 F350 Crew Long, DRW, 2WD, 460, C6 PO was trying to part out, saved this survivor.
-87 F350 Crew Long, SRW, 4WD, 460, C6, has an engine issue, thinking diesel conversion.
-88 F250HD, 7.3, 4WD, bought already as parts truck, apart and becoming a trailer.
-89 F250LD, 300, 4sp, mostly apart, donated many parts to worthy projects.
-89 F350 Crew Long, SRW, 4WD, 7.3, C6, was daily till C6 blew, converting to ZF5.
-90 F250HD, Ex-cab, Long, 4WD, 7.3, ZF5, just got, PO had dash fire.
Does your air pressure build up as normal? Do you have the receiver drier on the truck? Are all the ports correctly attached, the threadle valve shouldn't leak any air, when you release the parking brake your charging the chambers, if you have a tear in one of those diaphrams it will force air back up to the foot valve and cause the air to come out of the open port, but the chambers have holes in them so you would hear the leak at the wheel. I would make sure the foot valve is in correctly, they are labeled and should come with spare plugs, to close off the none used ports.
1999 F-350 PSD, 6 inch all spring, 35" Toyo load E tires, 140 gallons of fuel, Detroit true trac front, Detroit locker rear, BDS trans, banks billet converter, banks trans command, TS chip, banks turbo housing, wicked wheel II, FRx Kit w/black spring, Non-EBV Pedestal, diesel site coolant filter, 203 t-stat, IAH delete, 4" turbo back exhaust, 6.0 trans cooler, Riff-Raff wastegate, 1994 Ford f-350 ambulance, 7.3 IDI 40,000 miles, rear air suspension, full light bars, strobes, sirens ect. for sale
Check your brake cans, I suspect one of them is bad. One of the signs of a blown diaphragm is a release of air at the foot treadle when applying the service brakes.
__________________ 90 F250 7.5L E4OD, 03 F350 SD auto with the infamous diesel 6.0 for work, 70 C600 330 MT40 auto dump truck O2 Oldsmobile Bravada, Kubota L3200, Hustler Super Z mower, all Hydrostatics, 85 Honda Elite 250 & 150 scooter CVT - Nary a manual in the fleet!
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.