Question about vu4 air ride manifold - The 1947 - Present Chevrolet & GMC Truck Message Board Network

t76turbo · 10-17-2015, 05:17 PM

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.

stevencvn72 · 10-18-2015, 10:04 AM

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/

andrewmp6 · 10-19-2015, 01:39 AM

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

t76turbo · 10-19-2015, 10:13 AM

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.

Pro Performance · 10-19-2015, 10:50 AM

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....

PBFAB.COM · 10-19-2015, 06:56 PM

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.

10-17-2015, 05:17 PM	#1
t76turbo Registered User Join Date: Dec 2010 Location: N.E. Florida Posts: 215	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. __________________ 1970 Shortbed 2wd C-10

10-18-2015, 10:04 AM	#2
stevencvn72 Kill Bill...et Join Date: Aug 2008 Location: Winchestertonfieldville, Wa Posts: 366	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/ __________________ -Steve I ♥ Grease '67 Chev stepper http://youtu.be/38p_2Iu2fd0

10-19-2015, 01:39 AM	#3
andrewmp6 Registered User Join Date: Jan 2009 Location: Louisville,Ky Posts: 5,811	Re: Question about vu4 air ride manifold Yeah you need a one way valve aka check valve like said.

10-19-2015, 10:13 AM	#4
t76turbo Registered User Join Date: Dec 2010 Location: N.E. Florida Posts: 215	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. __________________ 1970 Shortbed 2wd C-10

10-19-2015, 10:50 AM	#5
Pro Performance Registered User Join Date: Aug 2010 Location: AZ Posts: 3,069	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....

10-19-2015, 06:56 PM	#6
PBFAB.COM Senior Member Join Date: Dec 2003 Location: Mesa,Az Posts: 3,981	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. __________________ www.PorterbuiltFabrication.com Phone: 480-297-2621 E-mail: sales@pbfab.com Find us on FaceBook under Porterbuilt Fabrication Specializing in Chassis and Suspension Components for your Classic Chevrolet Truck. We offer components from the following manufacturers: Porterbuilt Accuair Ridetech (Air Ride Technologies) Air Lift Wilwood Intro Unisteer ECE Gotta Show Air Lift Borgeson CPP Supporting this forum since 2003!

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