I have a 2002 S430 which today while driving lost pressure in the right rear air strut. I restarted the car, the strut inflated normally and drove it home. By the time I reached my driveway, approx. 4 miles, the strut had lost it's air charge. I restarted the car, the suspension inflated to normal height, I put it in the guarage and it is holding pressure normally.
Any input would be appreciated.
Thanks for reading
Brian

suspension valve block?

Height sensor?

Probably the strut. Put the suspension in the raised mode and bounce the car up and down listening for air leaking.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

the strut goes all the way down to the bottom when driving so i think it's a good conclusion the strut isn't leaking otherwise it would stop when below the fully raised or bounce height. Thanks for the idea.its a good start

This morning the car was still almost normal but the right rear strut was down about half an inch. When i started the car it inflated to normal height until I put it in reverse. The right rear strutimmediately started to deflate until it was fully deflated. Turned of the car and restarted. the strut inflated to normal height so I had someone else put the car in reverse. I could hear air at the rear strut either valving or leaking. Could not tell which. Restarted the car, it returned to normal curb height., turned off the car and left it there. Came back out about a half an hour later and the right rear had dropped again a little but so had the right front. Am I looking at a bad strut?

ideas?

Sorry I thought I had posted the conclusion. Rear strut was leaking as was suggested. Thanks for your help