Norgren venting opening leak

[PrevostNewbie]

Mark, do you have a screenshot of the schematic of that area like I posted for mine?

[Fratto]

This is pretty close. The accessory manifold shown as one is really two but that should not affect this.

[PrevostNewbie]

Maybe the clue here is when you raise the bus up it doesn't leak. With the key on or off, that bottom valve is spring loaded to one side closing off the exhaust port. when you try to raise the bus pilot pressure from the top valve on the Norgren stack pushes the spool on that bottom valve and compresses the spring, closing that exhaust port. If you remove the 2 airlines circled in red you will be able to see if air is coming back thru either of those lines like Joe is recommending. If there is no air coming back from either of those 2 lines, then it is a valve leak from port 1 to port 3. Worth a shot?

[Joe Camper]

The spool can leak 8 different ways it may or may not also be leaking there that tells nothing. Even though there is a leak evident out the exhaust port it may or may not be coming out that top port at the same time it all depends on what o-ring Rings leaking on that spool and how bad it's leaking

Mark. U have placed a valve failure in front if me I've nere had without it being the valve on a suspension corner creating it.

First

If u close off the black 1/4 in signal line on the offender I'm quite confident the leak will stop that tells me the norgren itself is no good but if if that valve is normally in the resting position only requiring a signal to open and exhaust then there's should be no pressure present in the line to begin with and the top solenoid on the air manifold is also bad.

Either way just a new 2 position spool will stop that leak but if you have a slight bit of air coming out of the norgren air manifold into the signal line on that two position spool there's also a slight problem leak at the solenoid the top one on the norgren air manifold that's going bad too. that will be masked now because the air leak that's beginning on that component is just Dead ending at the norgren that's now air tight.

And if you just replace top coil and valve on the air manifold that well stop the leak at the bottom norgren but the bottom norgren is still bad the leak will still be there but only when you're exhausting and you'll never hear it or know it I would guess that either of those two components will effectivly stop the leak but both of them are bad.

[Fratto]

Thanks Joe and Mike

Replacing the bottom norgren seems straight forward. Joe, I understand that you prefer to use new compression fittings on the new valves and go to compressions right?
By the way, are the push to fit removal pliers worth it?

But the top valve on the stack, how does it come off of the manifold? Any youtube or other videos out there on this?

[Fratto]

Also, all of the existing fittings have sealant on them ... what kind do you recommend for the new fittings?

[Gil_J]

There's too many possibilities. It's easy enough to troubleshoot with a couple of connectors and shop air. Easy first. Disconnect and cap the control line going to the valve. Toggle the control valve with shop air. If it works right, the control supply source is the problem. Next, add a valve to the input. See if it still leaks after aired up and the valve turned off.

[Joe Camper]

Gill, we know the valve is leaking. We have eliminated the possibility it is a suspension leak feeding back because it continued to leak all suspension emptied out. The only other air supplied is to the signal port and it is coming from the top coil pac on the air manifold. If air is coming from there without being on the button in the cockpit it is also bad. Both components r bad and replacing either one will stop the leak he will prob want to replace both.

Mark that particular push in fitting is not critical the air tightness of anything the only time air is coming down through that tube is when you're on the down button on level low so you can replace it with a better one but it's really not necessary if you do you'll have to shorten up the 3/8 plastic tube about a half inch or the bottom valve won't line up with its holes again.

As for the air manifold and coils. Remove the eclip on the stem and pull the coil off the valve you shouldn't have to undo the n-terminal with the wiring to do it it'll just pull aside. Then there's two very small screws theres actually 4 look closely at them two of the four opposing screws release is it from the manifold and when you separate it if you look at the bottom of the valve there's two o rings there make sure either of those two O-rings didn't stay stuck on the manifold and make sure when you put the new valve in that you don't dislodge those orings going in.

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Only stuff I will use. Never use on the compression end of the fitting only put on the pipe threads. Wire wheel the pipe thread end of the fitting to eliminate any burr that could plow out aluminium thread in the norgren and have the shaving end up on the spool before putting the pipe dope.

[Fratto]

Awesome. Thanks Joe and others for the help. Getting my head around the air logic is worse than my first circuits class ... of course I dont remember any of the either!

[Joe Camper]

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I would say u could not prove what was leaking first. Ither leak alone would be undetected because If fit were only the norgren it would only leak when u were on the down button and the other air exhausting was hiding it. That's the only time pressure is present on the spool end.

And If only the coil controlled valve on the manifold were leaking and the norgren air tight like it should be that leak would just dead end at the signal supply port on the norgren. All that would happen is it would pressurize the line between the 2 when it otherwise should not be.

Does that compute?