Question about vu4 air ride manifold
 

I have the vu4, porterbuilt bracket with viair compressor and 3 gallon tank. I had a leak in a pipe plug in the end closest to the cab and couldn't get a tool on it to remove the pipe plug to reseal it.

So I put extra air in the bags to give me more room to get to it and removed 3 bolts to drop the end of the tank. When I drained the tank the bags lost all pressure and dropped to the ground.

Just side note. I only have bags in back now and have the front bags and PB lower control arms with the drivers side compressor bracket, tank,and compressor waiting to be installed. So for now the ports for the front are capped till I put the bags in. I am building a big block with Chris Straub cam and 049 casting heads now and am going to install all this at one time.

I thought the vu4 would hold pressure in the bags even if the tank is empty. Am I wrong??? I plead ignorance.

Re: Question about vu4 air ride manifold
 

You'll need a check valve between your tank and VU4. Check out pro performance. That's where I got mine, plus if you lose a tank fitting, you wont beach your truck in the middle of the street like I did.
https://www.azproperformance.com/Suspension/

Re: Question about vu4 air ride manifold
 

Yeah you need a one way valve aka check valve like said.

Re: Question about vu4 air ride manifold
 

So just to be sure I understand. The VU4 is NOT supposed to hold pressure on each bag if the tank goes empty???

I will look into a check valve right away. I appreciate both your responses.

Guess I need to order 2 check valves and another water separator for the new setup.... I forgot about that.

Re: Question about vu4 air ride manifold
 

It should hold air when the tank is empty. The vales inside the VU4 will stay closed and keep air in the bags. Call me, and we can check out a few things. I have had low air or empty in my tank before, and the truck is still up on the air bags....

Re: Question about vu4 air ride manifold
 

The valves are not designed to hold with zero back pressure. If the pressure in the supply side is less than the feed side, the pressure will equalize.

I found this out in a similar fashion a long time ago. :)