Losing air pressure

[@jackschissler255]

Amazing what they design and the little screws and springs in them.

[@txstreetman]

That's not a servo. It's a heating element which keeps the water from freezing in cold climates. That purge valve is completely rebuildable--especially if it is a Bendix AD-9 dryer. The purge comes from the unloader valve on the governor--there is a line from an unloader port to the dryer, and when the unloader stops the compressor, the air is routed through the unloader line to the dryer, which opens the purge valve to "spit" the water out. My Thomas did not have a dryer when I bought it--just a pull cord. I ended up getting a used AD-9 dryer off of a semi, and added it to the system. Easy mod....

[@marshalllhiepler]

Yes. You are correct. He understands 90% of how it operates, but lacks a complete understanding. Enough to fix it by replacing parts, but not enough understanding to explain its operation fully and correctly. The dryer's Purge Valve is the path, by which, the dryer expels water from the system. It is normal, to see residual water in, and around the Purge Valve. This does not indicate a faulty Purge Valve. Rather, it indicates that the dryer is removing moisture from the desiccant canister, as it is designed to do. As "tvstreetmsn" stated; the Purge Valve in this video could have been rebuilt with an available soft-parts kit, at some savings to the customer.

[@Joeyouwont]

It's always this time of year

[@LouSassoleS]

How much air pressure should i lose on my box truck overnight parked? Please i have same issue, i changed the foot valve quick fittings that were leaking but truck still loses air pressure overnight to zero.

[@napoleonarmstrong3648]

Hey there Joe..long time buddy. My 01 4300 was building pressure over 150 psi and alarming. I bled the lines and all.kinds of gunk came out. Replaced Governor and valve yesterday and today it worked fine for an hr now I lose pressure whenever I hit the brake and it won't rebuild. I pull over and bleed the brakes down and let it rebuild before resuming only to have the same thing happen. Does it sound like tanks are gone?

[@JoesBusBarn]

You might want to check the pressure regulator on your tank or tanks.

[@zaidchalabi1599]

awesome stuff man i have kind of same issue with my truck i also lose more than normal air pressure when holding service brakes. if i stop at a traffic light and hold brakes then drive a mile and face another traffic light my pressure will drop under 60 and buzzer will sound. it will take like 5/6 miles driving to go back to 120 its just so damn slow to go up and drop fast you think its a leak ? or bad air compressor

[@JoesBusBarn]

Hey there Zeid. Sounds like u might have a leaking brake chamber my friend. Have someone walk around the unit while you hold down the brake pedal. You might have a bad chamber. Very easily found with an assistant.

[@zaidchalabi1599]

@@JoesBusBarn how much fixing sonething like this cost ? also why filling back up with air to 120 slow ? when i drive after it had dropper ? the brakes wouldnt be engaged so that means leak somewhere else no?

[@JoesBusBarn]

Brakes will only lock up when pressure drops to under 30. Then ur park brakes kick in. Brake chambers are not that expensive. There r 2 types. Short and long stoke. They run around 60 bucks or so.

[@JoesBusBarn]

The replacing of chambers is not to hard. You could DIY it or take it in for service. They probrably charge u like 2 hrs labor. I don’t know what the cost per hour is at ur location.

[@zaidchalabi1599]

@@JoesBusBarn but you think brake chambers bad themselves of brake hoses going to them ? also do i need to replace slack adjuster,scam and bushings with the chambers? i heard its recommended to do all together last question is say i need to change driver side steering axle brake chamber, do i changr both sides or whole truck or just one i suspect leaking ? thanks