Update time!
The suspension continued to jack the front end way high as the car drove around. There are leaks, so it settles back down in a few hours, and on initial startup, it levels nicely. It just seems that the longer it goes, the higher the front end gets.
It appeared that it was unable to vent in order to control the lowering of a high corner, and since the vent system is actually in the compressor, we'll look at that when we remove the compressor. The rebuild kit arrived last week, so last Saturday was Job Day.
The compressor is behind the bumper, in front of the left front wheel, so i jacked the car up and removed the wheel, along with the fender liner. This is what I saw, which I've labeled.
Having learned some things about how the system works, I'll lay that out for you. The compressor lives up front, as shown. The computer lives (inconveniently) behind the back seat's rear cushion. The rest of the control system lives under the spare tire in the trunk. There you find a pressure tank, kept between 9 and 11 bar, and a valve body with solenoids to open air paths to various places. The system operates from pressure in the tank, and the compressor merely maintains that pressure; it doesn't act directly on the struts.
The compressor has a tube through which it sucks atmospheric air, and also vents excess air from the struts when necessary. Air is pulled through a fuel-filter type canister into the compressor's cylinder, and compressed air passes through a desiccant chamber and out a pipe that goes to the valve body in the trunk. When the compressor's running, the valve body opens valves to the compressor and to the tank, so compressed air fills the tank.
When a strut needs to be lifted, the valves to the pressure tank and that strut are opened, allowing air into the air spring, raising that corner of the car.
When a strut needs to be lowered, the valves to the strut and compressor are opened in the valve body,
and the vent valve in the compressor is opened. Air passes from the strut to the compressor body, where it exits via the vent solenoid valve, through the filter backwards and out to the atmosphere. This is what I think was not happening.
When I started pulling electrical connectors and air tubes off of the compressor, I knew there'd be a moisture issue as water dripped out of the compressed air tube. Well, I'll look at that later. First the new piston ring. The cylinder comes off with just two fairly substantial screws, and I find the piston there with the ring ready to be removed. The old one definitely showed some wear:
On opening the desiccant tube, I found a
lot of water. The beads were clumped like cat litter, and each end of the desiccant cylinder had a perforated disc covered with a felt washer, and the discs were rusty and the felt was soaked. I poured the desiccant out into a pan, then dropped some on a paper towel. You can see how wet the towel got under the beads, which shouldn't happen - desiccant should be
dry:
The top disk, and the spring which holds it against the desiccant, were both rather rusty, so some fine-grit sandpaper came to use. The vent solenoid at the other end wasn't rusty, but did have a good bit of gunky green corrosion. That cleaned up nicely, so here's hoping.
I ordered the smallest package of bulk desiccant beads I could find, which was 1.5 pounds, about 5 times as much as I needed, but there ya go. That arrived this week, so I was able to reassemble the compressor yesterday and got it reinstalled into the car this evening.
On startup, the car leveled out correctly, and although I didn't run any great distance or amount of time, the front end remained at the proper height, so in the hope of not speaking too soon, maybe those issues are taken care of.
I still have the leaky fittings to address, but as long as the car raises when I start it, the priority on that is not as significant.