[95murderedChevy]

I don't know the best way to explain this but here it goes.

I'm running 6 3/8 smc valves. 4 for the front 2 for the rear.

I've checked multiple times over and over looking for wiring issues, and have found nothing.

When I lift the front the dump valves are sticking open and draining all tank pressure from my tank. If I tap the the dumps they stick open also and lay the truck out. Here's where it gets confusing, I do not see how I could have faulty valves already! They are only been mounted and wired for just over a week now! I'm stumped unless Teflon has somehow got in.

I also did have to remove the diaphragm to be able to plumb them in the 90 degree setup I have them plumbed! May have assembled back wrong but I seriously doubt it. Any info/input is helpful. Thank you in advance!

 

[Dropem]

Sounds like something is stuck in them or making them hang open. It doesn't seem to be a wiring issue to me.

 

[LaydoutZ71Rado]

If you don't have airline coming from the dump valves then you need to. Put at least a 6" piece of line out of each dump valve and this will cause back pressure on the valve thus forcing the valve to close and not stick.

 

[Tukn4s]

If you don't have airline coming from the dump valves then you need to. Put at least a 6" piece of line out of each dump valve and this will cause back pressure on the valve thus forcing the valve to close and not stick.

it doesn't matter if you have a 6" piece of airline, no air line or 24" of airline out of the dump valves. If it is open to atmosphere, then it will be the same pressure regardless.

Valves use pressure that is supplied to stay closed when they are not charged. when you energize the solenoid, it opens the gate AGAINST that pressure. this is why, if the pressure switch doesn't kick the compressors off, the tank can build to much pressure and you can't open the valves until you drain the tank a little.

Dump valves are the same, as soon as you have fill the bags, the pressure will keep the valves closed. as soon as you energize the valve, it opens against that pressure.

Also, in the valves are a spring that trigger the valve closed after you release the switch. otherwise, after you get below 15psi, atmospheric pressure would open the valve.

this is also why, if you don't use check valves and the tank leaks below the bag pressure, it will leak back into the tank.

 

[LaydoutZ71Rado]

it doesn't matter if you have a 6" piece of airline, no air line or 24" of airline out of the dump valves. If it is open to atmosphere, then it will be the same pressure regardless.

Valves use pressure that is supplied to stay closed when they are not charged. when you energize the solenoid, it opens the gate AGAINST that pressure. this is why, if the pressure switch doesn't kick the compressors off, the tank can build to much pressure and you can't open the valves until you drain the tank a little.

Dump valves are the same, as soon as you have fill the bags, the pressure will keep the valves closed. as soon as you energize the valve, it opens against that pressure.

Also, in the valves are a spring that trigger the valve closed after you release the switch. otherwise, after you get below 15psi, atmospheric pressure would open the valve.

this is also why, if you don't use check valves and the tank leaks below the bag pressure, it will leak back into the tank.

I've always been told to have at least a 6" piece of airline out of the dump valve for back pressure to force the valve closed. The reason I was told this is because I used to run straight dump valves (no airline on the dump valve) and it was doing the same exact thing that 95murderedchevy's is doing. I called some shops up (ekstensive and avs I believe it was) and that what they told me to do..

That's why I recommended that solution.

Mine would always want to stick on hot days and now I have 0 problems after putting some airline on the dump valve.

 

[Tukn4s]

Ran smc dump valves straight open for 8 years with no issues.

Having airline off the dump valves doesn't create back pressure, you can't build pressure that way


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[LaydoutZ71Rado]

Ran smc dump valves straight open for 8 years with no issues.

Having airline off the dump valves doesn't create back pressure, you can't build pressure that way


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Hmmmm... It worked for me lol

I ran straight dumps for about 6 months before they were giving me problems.. But they were also in the bed exposed, so maybe the moisture would build up inside the valve from direct exposure to rain and the weather would cause the spring to stick?

When I would dump the bag the valve would stick until it hit a certain point in pressure then it'd close.

So in theory, if putting the airline of the dump valve didn't solve the issue, what do you think did Brett?
:crazy:

 

[Tukn4s]

If they were open to the elements or you don't have water traps then it was probably moisture. The airline was probably a suggestion to keep dust/debris/water out.


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[95murderedChevy]

I pulled them all apart and nothing seemed to be wrong looked fine.
I've never heard of putting air line on the dumps and I honestly do not see how
It would help but hell I'm game to try it lol. If this doesn't fix the issues I may end up going back with manual valves.

Also the only time they do stick is when it's hot and there in direct sunlight. I shit you not just yesterday it was hot
Out I drove the truck and they we're sticking.
Brought it back home pulled in the shade washed the truck, which I'm sure that cooled them off some. And BOOM, no sticking valves! I don't get it lol, I've used smc valves (older smc's) on about all 3 or 4 past trucks I've had NONE have done this. These newer style valves in my opinion are just garbage! What's the next best valve out there?

 

[95murderedChevy]

I was thinking maybe GC?

Honestly may just save up and try accuair... before I resort back to the primitive days of ball valves lol!

 

[LaydoutZ71Rado]

Let me know if the airline works. I don't know how it worked for me, but mine used to be in direct sunlight and they stuck too when it was hot and yes in shade they wouldn't stick either. Somehow the airline worked for me. It was weird

 

[Tukn4s]

The issues you guys are having with the sunlight more than likely stems from the solenoid itself getting too hot. the cheap SMC valves which are the most common ones, will have issues around 125*f. now if you start using the valves and they've been sitting in direct sunlight all day long, chances are they will stick. the valves themselves under use raise their temperature.

I ran the same cheap 3/8" SMC valves under my bed floor open straight to air for over 8 years wired up on 2 different trucks, without a single issue sticking.