Agree with all below, and add that the control valve is supposed to maintain a factory-set base pressure on the strut/accumulator side, regardless of the position of the lever. This base pressure is the required pressure to keep the rear end from sagging when the car is in "ready to drive" condition (i.e. no cargo, but full fuel tank, spare tire and tools in place). If the system is operating correctly, the only way to relieve the base pressure is by opening the bleed screw on the control valve or make a leak in one of the lines to/from strut and accumulator.
-Max -----Original Message----- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com] On Behalf Of Fmiser Sent: Friday, January 07, 2011 1:10 PM To: Mercedes Discussion List Subject: Re: [MBZ] 500SEL hydro suspension still acting up (or down) > Alex Chamberlain wrote: > Right, let's stipulate, as our colleague Snook, Esq. would > say, that I already knew that. ;) The question I should have > posed was, does the main flow control valve allow the > high-pressure fluid from the pump to enter the rest of the > system (i.e. the level control valves, struts, and nitrogen > spheres) at all times? Or does it merely recirculate the > pump's output back to its input via the reservoir unless > additional pressure to compensate for added cargo weight is > required? Which is the case with rear-only SLS? (It's very > likely the same answer for both systems, I think.) I can only speak as an authority on the S123 system... The pump output goes into a hose with a anti-cavitation restriction in it and then into the hardline that connects to the valve inlet. Unless the valve is positioned to supply pressure to the struts (I'm lumping the accumulators in the the struts 'caues for this discussion they work as a team), the inlet flow is routed to the return line. If the valve is positioned to release strut pressure, the strut oil plus the pump oil is returned to the tank. The only filter is on the return flow as it enters the tank. This means most of the time the only place there is any significant pressure is between the pump and the anti-cavitation piece, and between the valve and the struts. The rest of the system is just flowing. I suspect that is how the other systems work also - but that's just a guess. I have photos of the insides of the S123 pump and valve if anyone cares. -- Philip _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
