I've replaced front and center valve block (not Chinese knock off) in the past couple of weeks and spraying soapy water there but no signs of leak. When I got the truck to rise a few weeks back I pulled the fuse and it sat for 2 weeks without dropping on any corner.

I still need to calibrate correctly but without the reservoir filled I cannot adjust accordingly, so I think the truck did some adjusting overnight. I don't park on a leave surface either. Saturday, I can't recall if the truck dropped down when playing around Saturday but that is certainly a possibility and it's done that in the lead up to this.

 

Just for more info, when the front (or rear) lowers due to a valve block - it is usually leaking past the block's o-rings, back into the system thru the pipes . . .

Not via an external, visible (bubbly) leak to the atmosphere.

 

Cheers, Doug. Given I've recently replaced front and mid valve block, can I rule these out as having further issues?

 

Likely yes, they are not the problem.
Have you sprayed the pipes and fittings near the compressor, center valve block, reservoir, etc to check for leaks?

 

I did some soapy water tests but couldn't see anything. I'm going to spend the coming Sunday doing it again in a much more comprehensive fashion, ensuring I don't miss anything.

 

Well valve blocks themselves can leak, that has been shown to happen in a couple thread. How, I dont know. But they body itself can indeed leak. Also you need to check the struts for leaks, not just the blocks.

Another option, if creative, is to use a shop compressor to inflate each strut manually. Use push-connects and a pressure gauge. Inflate and see how it all works out and if the struts hold air at different heights.

Also when inflated, bounce the front end. Sometimes a strut leak will make a loud sound as you bounce and you can hear the air shoot out.

 

This would point to the valve blocks being OK and possible issue with struts. It is typical for the struts to leak at different rates at different height settings; at different heights the air bag effectively seals different parts of the bladder against the aluminum housing. For example, parked at normal height, my truck will settle about 1/8” per day for a couple days, and then taper off to 1/16”. At off road height, this rate is about 1/16” from the start, but around day 3 the bag seals itself and no more movement indefinitely.

In addition to all the other good leads you have, I would park the truck at off-road and monitor the height for a week. Then reset at normal height for a week. See if the change is constant or different between the two.

 

Thanks for this info, really useful as well. I parked for 2 weeks at normal height, pulled the fuse and no change whatsoever to the height of the vehicle. I managed to get it in off-road, so I raised the truck and it's been sitting at the same height since Sunday (6 days now), with no drop whatsoever. I've taken the truck out a couple of times, been told off by constant pings (I know, Suspension is faulty), and even loaded up with mulch and still no drop in height. So I don't think it's the struts. Given it's not dropping, can I rule out a leak in the pipes between struts and valve blocks?

 

That pretty much rules out issues with the struts and front/rear valve blocks.

Next thing to check would be reservoir tank and center valve block. If one of these has a leak then your air compressor is running overtime trying to fill up the tank which will overheat the compressor every time. The tank is so large the compressor has to cycle several times to fill it if emptied.

The reservoir tank is easy to remove to inspect and replace. Give it a visual inspection for leaks once removed, and if you have an air compressor you can fill it up and rig up a pressure gage to monitor pressure in the tank.

You should also check your center valve block piping for leaks. IIRC this is what actually articulates to allow pressure to flow in or out of the tank. If you have a leak here from install, that could easily be your problem. I’ve never removed an air suspension part and not had it leak out of the gate from at least one fitting!

This is all pretty much what has been suggested by Dakota Traveler and Doug, so I think it’s all adding up.

 

Still no luck getting to the bottom of what is up.

I've done a soap test around the pump and center block (recently replaced), and no visible signs of leaking. I've also checked the reservoir line and cant see any signs of leakage.

I've got the Arnott P-3431 compressor. I ordered a dryer and o-ring kit from 4x4seals, replaced all and the issue still persists. The desiccant wasn't terrible but there was signs of it breaking down so I gave everything a good clean and put back together.

Running some live values the compressor runs again for 20-30 seconds before cutting out. Gallery pressure isn't rising above 14psi... I used the Gap tool to try to vent the reservoir to see what might happened and the tool stalled (I guess because the reservoir is empty)...

Getting to the point where I may bite the bullet on a new compressor.