Air bag & tank??

I just got done doing a air bag suspension on a 78 Elco. I had the Elco aired up and had to do some work on the tank, so i let the air out of the tank and the Elco layed out. I'm under the impression that if the air bags are aired up that the air valves would hold the air in the bags? If any body can help i would appreciate it.://i1182.photobucket.com/albums/x444/Pachecokustomz/IMG_20100916_165346.jpg

All the valves I have ever had are directional. If the bag pressure exceeds the tank pressure (especially under a load) the valve will back flow to the tank equaling out the two's pressure. The only way to prevent this, is to install a check valve between the tank and each pump valve.

Is there an engine in that car?

Yes there is. when i opened the dran plug to let the air out the car layed out. left me scraching my head!! I'v done alot of Hydor's and never had that happen to me...so I was under the impression it was the same.

Thx

Yeah man, when you drain watch your toes! LOL

Hell ya thank god for steel toe shoes!! LOL..

Most valves have to have back pressure on them to work. So if you let the air out of the tank, you will lose back pressure and the bags will deflate.

yes check valves are your friend