I have been sorting out this bugger for a minute but the gallery pressure is dropping 1-2psi a minute (somewhat faster at higher pressure) regardless of whether or not it the engine is running. I changed out the front and rear valve blocks, the resi valve block, new compressor too. Sprayed all fitting locations but no bubbles. Sprayed gallery tank no bubbles. Desiccant tank cap no bubbles. No bubbles from compressor. Front struts are new. II figure it can't be the rear struts since this is the gallery pressure that is dropping constantly with engine off or on.
Is there a common spot on a pressure line that wears through???? Could it be the rear struts???
I have not yet pulled fuse #3 and watched it over night since I just replaced the blocks and it is still on stands.

 

Thats really nothing.

The gallery can only leak:
• At the main line to the front valve block or the main feed line to the rear valve block and the feed line from the compressor to the center valve block (blue connection on dryer). This would be rare given the type of connection that is used.
• At the dryer assembly is can easily leak at three places. Each dryer cap push-connector (blue/orange) and at the interface between the dryer and compressor (this o-ring can easily be damaged if the dryer is installed without lubricating the o-ring first.
• At the exhaust line into the exhaust header. This is the "orange" line out of the dryer cap and loops back into the compressor. This is the exhaust line.
• At the pre exhaust port. This is a small rubber plunger held by s light spring under a "bolt" on the compressor. A kit for these is about $20. The rubber hardens and does not provide a good seal.

So basically if the gallery pressure is dropping, its usually happening at the compressor or around it. Since the front and rear valve blocks are, in theory, closed you can no loose gallery pressure past the front/rear valve blocks. And the center valve block is more of just a junction that also leads to the reservoir. So when the system is not active the reservoir is sealed off too.

Keep in mind that before the compressor runs is actually blows off gallery pressure to drop head pressure so it can run or else it would be fighting a lot of pressure to get started up. Overall the gallery, by volume, it not a ton of air and is recovered almost instantly when the compressor runs. Now a leaking reservoir, that would be a concern to me. But if you really want to find this leak, you need to spray more soapy water. The push lines are what usually causes the issue because they get beat up being taken in/out of the fittings improperly. One is suppose not push the line AND collet inward at the same time, then back out the line. Some people hold the line and push the collet only. The small brass teach inside scratch the line. This results in damaged to the o-rings and causes small leaks. And if its a cheap compressor, then they just leak cause they are cheap and the o-rings seal like crap.

 

Thank you so much!! I have covered those locations except for the base of the dryer can. Yes this is one of those ebay hitachi copy compressors. When I first installed it, I got the code about relief valve being stuck. The guy said it was the little rubber piece under that 14mm? cap screw so I replaced that $20. Sounds to me like the relief valve may have to do with that diaphragm looking square on the compressor?? Regardless, I pre-filled the gallery to 150psi but now I get C1A00 control module and the yellow eas light almost instantly. It shows standard ride height but the car is on the stops so I can't even pull fuse 3 to check for corner leaks. This car is dying a fast death.

I have a 2004 D2 that is great. My daughter gave up on this LR3 and went down and bought a new Disco Sport. Now I am just pissed and I don't want this thing to win.

 

Yeah, might be called a relief valve. I will say that is that little bugger is bad it will cause a compressor to work overtime as its a leak of any pressure it tries to build too.

That square thing is the exhaust valve. Keep in mind the exhaust valve itself not operated electronically, its a rather large piston. A small "pilot valve" on a solenoid (blue/white wire if I recall) opens and gallery pressure causes the main exhaust valve to open (spring loaded). So, thats how that bugger works.

Did you have a Hitachi version before? Did you put in a new relay? Relays are replaced with compressors because a dying compressor is hard on them and can burn em up enough to create their own issues. So a good practice is to replace the relay. I think its a pretty standard $10 Ford relay. And for testing you can probably swap it with something non-critical.

C1A00 - odd case that seems to imply the brain box is an issue. Fuses are good? Do you have extension rods on the sensors installed (I assume not, cause this does not quite sound like an issue they normally cause)?

edit: Oh, the code could also come up if something is not connected right, such as the second harness at the compressor. And your issue has nothing to do with gallery pressure, so you can stop chasing that thing.

 

It had the Hitachi before. I rebuilt it a couple years ago, new piston, cylinder, that little poppet valve, new dryer top, etc. It worked fine until recently when the RF bag started leaking. I installed two new struts on the front and it started going down hill from there. So, after that, the gallery would leak down cycle, eventually leading to compressor fault. Replaced compressor with the ebay version and immediately got that exhaust valve fault with the car stuck in off-road height. After a week, the front dropped to bumps then the rear a few days after that. From there, I installed all new valve blocks, and bench tested the compressor. I modified the poppet valve as they have a design flaw that prevents the valve from opening at all. simply took .030" off the back of the rubber piece. Reassembled, pre-charged air to 150psi and soaped everything. No leaks but gallery drops as I explained. Started car, cleared codes and immediately get C1A00. Can't raise or lower --- that may mean something. If it will not lower, that compressor exhaust solenoid must be stuck.
On the relay, I bet it failed if that compressor had to start against a high head pressure.
The ebay guy is sending another compressor so I will try that too. And another relay. If I still get C1A00, I guess it is new control module time.

 

I really doubt the control module is bad. I mean if you can read gallery pressure its being processed by it. My gut says the issue is wiring related. Could be the relay but it could be a connection too. You did a pretty big overhaul, it should be working.

Note: You are not in tight tolerance mode or build mode by chance, are you? Even if not, set it to normal mode if you can (I dont have a GAP tool so I dont exactly know how it works).

 

I just have ICarSoft for the LR3. I can data stream, clear codes and read codes That is about it.
I am thinking now that I will pull the compressor and dig into that solenoid a bit. I bet that has something to do with the issue or that piloted exhaust valve you mentioned. If all else fails, I will pull the module and take a look for any visual circuit board failures.
I may end up with the GAP tool since I found a source that includes a free key fob with it for $500. Since I am down to one key, it may not be too bad of a deal.

 

As you have changed two struts (going downhill after that) I would review those bags and the air connection to the top of them as you may have a problem. Check with a spray of soapy water, include the rear cap of the compressor as they do crack unless its a metal one.

 

Nope, it would not be an exhaust issue.

Airbags clearly not an issue at this time, the front valve block has them sealed off. This is a soft fault related to something else because if the air bag connections were bad the fault would be related to pressure increasing too slowly, etc.

 

Good point