Question about my air valves and stuff

[jimmydean]

So the dump valve is normally closed. So if I add air to the bag, there is air in the line between the dump valve and the bag, right?

So why is it when I open the drain on my tank do I lose air in all my bags? If I understand how the system should work, the inly time the air should leave the bag is when the dump valve is open.

All I want to do is fix the leak in the left rear valve setup. But I have to put the whole truck on stands because when I drain the tank, I lose preasure in everything. Is that right?

[Shane]

I believe, but don't hold my feet to the fire, the reason is because the valves use the residual pressure in the lines/tank to keep the valve closed.

Once energized, it will open ... but if there is no pressure in the lines/tank, then there is nothing there to keep it closed and then the "back pressure" in the bag will force the valve open.

[entourageguy]

you should be able to put a one way valve in there somewhere to stop that.
Brian ..

[jimmydean]

Shane, that makes a lot of sense. That's sort of what I was thinking, so that leads me into another question. How much back pressure is needed to keep the valve closed?

I think I have all my tank leaks fixed. Right now my passenger side holds air for at least 24 hours. The driver front loses air in about 8 hours, the driver rear loses air in about an hour. I am pulling it apart for the third time tomorrow once I shoot it with bubbles and see where it's leaking this time.

If I had an engine driven compressor, the leakage wouldn't bug me as much.

[PBFAB.COM]

Shane is correct. The majority of valves will use the pressure in the tank to keep them closed. If the pressure in the tank is less than the pressure in the bag and line, the valve will allow the pressure to 'equalize'... all the way down to 0psi. Doesn't seem right... but that's how it is.

[67Fleet]

You can put a check valve in between your line from the bags to the tank.

[jimmydean]

Man, I can't find a spot for my water trap, where the heck am I going to put a check valve too?

The good news is the front seems to be holding air now. I had 70 psi in the 3 bags yesterday at 5:00 and this morning there was still the full 70. If this latest "fix" works, I might have a somewhat leak-proof system!

[lost wages]

i had the same questions on my truck, i cut a line to redo some things and the whole truck layed out, i thought wtf? seems to me they should hold air if something were to fail while your driving. guess ill get to work on some bump stops just in case.

[droppedgmc]

go to www.*****************. they have the check valves. air valves have to have a constant preasure on them. when the psi in the tanks get low, it'll make your truck drop