I am trying to track down the cause of my EAS not building pressure. Symptoms are a recurring C1A20-64 code, amber fault light accompanied by "normal ride height only" message, suspension rising slowly warning if I am able to select off road ride height and a best of about 150psi gallery pressure. It builds pressure
v e r y s l o w l y. If I select off-road height, the back snaps right up and the front takes forever, if it makes it before it sets a fault.

I am new to the LR3 and am trying to read as much as possible, but I have not really found a good order steps to track my problem down. I haven't really found a good through explanation of how the system is plumbed or operates, so I'm trying to piece that together in pieces.

So far I have rebuilt the compressor with an x8r kit with new piston ring, glide ring and associated o-rings and drier refresh kit with an aluminum end cap. After re-installing the compressor nothing changed. I am currently in the process of letting it sit overnight, starting at off-road height, with the fuse pulled to disable auto-leveling. After about 8 hours I've had a 5mm drop LF and RR. I'll measure again before I leave in the morning. Unfortunately I need to use it tomorrow so it'll only sit 19-20 hours. I haven't noticed it dropping in the short time I've had it.

Thoughts I've had:
Air leaks- I checked the compressor fittings after re-installing with soapy water and found none there. I can't audibly hear anything. My thoughts were a leak bad enough to limit me to 150psi of pressure would be loud enough to hear. I may be wrong on that.
I've read there have been some air tank failures, but the ones I saw pictures of were pretty rusty. The underside of mine looks great, hardly any rust. Is there a way to test the tank with it in the vehicle?

What am I missing, or need to check?

 

There are 3 distribution blocks that can become contaminated with desiccant dust and cause a problem. Luckily, they are easily disassembled and cleaned... getting them out of the truck may prove to be a bit trickier. There are good instructions on here for doing this... hope this helps.

 

The rear valve was the only one that was a little difficult, I thought the center and front were easy. In my case, I replaced all three plus the compressor, which solved my lowering overnight issue. However, the compressor still seemed to run a lot. While the tank looked like new in the areas I could see, that was not the case where it's closest to the frame rail. I sprayed some leak detector in the hidden area and had lots of bubbles.

 

I have thought about the valve blocks but they were low on my list for 2 reasons. First, I don’t get much drop overnight, maybe 5-10mm. Certainly nothing like I’ve seen others report when they’ve had a bad valve block. Second, the desiccant looked better than I was expecting when I rebuilt the compressor. I may pull the front and do it since it is easy to get at. At the very least it’ll be eliminated from the possibilities. If there’s a sticky one I’m sure it’ll be the front since the back seems to work great. I’ll try some soapy water over the reservoir as well. I was just surprised at how clean it was under there. I read a few people broke the clip on nut for the compressor bolts when they removed the compressor, mine still looked like new. Benefits of living in a relatively dry climate.

 

I just went through the same process. Check my writeup here: https://landroverforums.com/forum/lr...diy-fix-86533/

The end cap was my issue. It had a hairline crack between the two ports. I replaced the end cap with the X8R version and that solved it.

However what you are describing sounds like my 2nd or 3rd failed attempt while rebuilding. I had the same issue. The rear would raise normal speed and the front wold be super slow and finally give an error. Since it was not doing that before the rebuild I knew I had screwed up something. I took the compressor apart and immediately found I had installed the thin metal flange between the piston housing and the base of the compressor upside down...

I flipped it over and that solved it the issue you are describing. I would check yours if you didn't have that symptom before the rebuild.

 

i read you post before I tore into it, When I read it I thought you were referring to the metal check valve between the cylinder and the head. But now it sounds like I was mistaken since you say it’s between the crankcase and the cylinder.

The frustrating thing is I don’t know if I botched it or it was never the problem. I may pull it and check my work after I attempt a front valve block cleaning and reservior soapy water spry down. At least I know I won’t have trouble removing stuck air lines if I pull it out again!

 

What I installed backwards was the "shim gasket" between the cylinder sleeve and compressor head. The instructables article reminds you to put it back in the correct way like 5 times...and I still screwed it up. There is a notch on one side of the gasket that corresponds to a notch in the head. It was obvious I put it in backwards because when I pulled it out the corner was bent.

Check minute 1:25 in this video Land Rover Range Rover L322 2006 +, Range Rover Sport, Discovery 3 EAS Air Compressor Repair Kit Instructions.: 11 Steps

 

Yeah, I was aware of that one. Partially from your thread and partially from rebuilding too many weed-eater carbs with all their little flipper check valves.

What I did wrong was install the cylinder upside down. I second guessed myself as I put it together, but it seemed like the fins fit better upside down. Because of this there was not an o-ring on both sides of the check valve “shim gasket” as it has been referred to. I now build up to 210psi or so gallery pressure before the compressor shuts off. That still seems a little low from some of the reading I’ve done, but since I’m not exactly sure what “the gallery” is it may not correspond directly to reservoir pressure.

While I was under there I gave it a good dose of soapy water over the compressor fittings and the reservoir and had no leaks I could see. I may put a new compressor on the list of things to replace, but for now I need good off road tires!

 

congrats on finding the issue! btw - how did you check the pressure?