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?
“If ye love wealth greater than liberty, the tranquility of servitude greater than the animating contest for freedom, go home from us in peace. We seek not your counsel, nor your arms. Crouch down and lick the hand that feeds you; May your chains set lightly upon you, and may posterity forget that ye were our countrymen.” ―Samuel Adams
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.
99 F-350 7.3 PSD 6" superlift springs, 35 toyo load E tires, true trac front, detroit locker rear,140 gallons fuel,Diesel-site coolant filter,6.0 trans cooler,BDS trans, Banks billet converter,Bank trans command,Banks turbo housing,wicked II wheel,Comp waste gate, Power elbow,diesel-o-rings in fuel bowl. 203 t-stat,TS tuner, 4" exhaust turbo back, AIH delete, Non EBPV pedestal, Banks turbine housing, B&S air cleaner with dry filter, FRX W/black spring 73psi, Pillar gauge set,
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. Ford® is a registered trademark of the Ford Motor Company.