Air suspension control

Quite possible, I've bought a couple of fittings this morning so I can set hook up to my workshop compressor and leak test it. I wouldn't be purchasing the same again, the whole experience left a lot to be desired.
I've got a couple of diff-lock air solenoids, I think I'll also test them to see how well they hold air pressure on the downstream side. If I'm not fully satisfied with the result, I might look at something like a D3 valve block and control it via the electronics I already have insitu.
I'll report back with my test results when time permits.

Thanks, I'll be interested to see how it goes.

A D2 valve block might also work.

Well, here's an interesting thing; I have not been able to identify any leakage at all across any combination of ports on the valve block. This seems to set my diagnosis on it's ear. The other thing is that the vehicle has held it's height without any drooping since I removed the valve block and installed the extra schraeder valves.
I'm not sure what to think. The obvious conclusion is that I had leaks at fittings that I did not identify, but I was quite diligent with the soapy water and could not find any hint of leaks, hence my thought that the air was leaking through the valve and out the exhaust port. This is not the case, at least with the valve block out of the vehicle, and there's no logical reason to think it should leak in the vehicle and not on the bench.
I guess it wouldn't take much of a leak to deflate an air spring overnight, the volume is much smaller than a tyre. I'm going to re-install the valve block and re-evaluate. The convenience of the remote-controlled valve is great if the system will stay where it's set. I'll get it back together in the next few days and see what it does.

Re-installed the valve block last week, mixed results so far. I did have one leaky fitting that I have replaced; with soapy water I could not find any other leaks but the car has done some settling, albeit less so than before. I'm going to give it a bit of time and decide whether to call it good.

Well, the re-installation of the remote controlled air valve re-installed the sinking suspension woes. I may have had a breakthrough though; I have added a one-way air valve to the inlet side of the valve block, so that if it is leaking back through the valves this should arrest the leak. Thus far it has held it's height for 4 days, although yet to be tested with a load in the tray.
I do recall that the suspension valve in the '94 RR that I mucked about with years ago had 2 stages of sealing; there was a valve for each spring plus an inlet valve and an exhaust valve, so that air had to pass 2 valves in series to get to or from the spring. I think the valve that I have probably has parallel valves for in & out of each spring. Seems this extra stage of sealing might be helping.

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Originally Posted by POD

Well, the re-installation of the remote controlled air valve re-installed the sinking suspension woes. I may have had a breakthrough though; I have added a one-way air valve to the inlet side of the valve block, so that if it is leaking back through the valves this should arrest the leak. Thus far it has held it's height for 4 days, although yet to be tested with a load in the tray.

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when you say inlet side, do you mean the line from compressor to valve block body or outlet side of valve block that is inlet side of bellow? If the former and the compr is not designed to remain pressurised (otherwise too high a load for start up), that would suggest a leaking inlet valve of your valve block. If the later, and if your valve block also doubles as your exhaust port for the system, the one way valves will stuff that up. Either way, I feel your pain of tracing faults.

I've added the one-way valve to the valve block at the port from the compressor. If this turns out to have fixed the problem (fingers crossed), it suggests that air was leaking back through the valve into the compressor side of the system.

Update; it's been a month and it seems the addition of a non-return valve on the compressor feed port of the control valve has solved the problem, the vehicle has held height including with a load. Pity it wasn't made properly in the first place, it was a very expensive piece. Nice to have the problem solved though.