Seat PSE issues and partial answers...
12-23-2011, 10:56 PM
#1
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1999 E55
Seat PSE issues and partial answers...
2004 S55 (but should apply to all W220 with dynamic seats)
Initial symptom was odd groaning sound (intermittent) under rear driver side footwell, and lumbar and bolster functions in drivers seat was erratic.
I exposed PSE (left rear side of trunk) and found the primary feed line (from pse to black reservoir) was leaking. Replaced line, but problem remained. (alhough pump cycled less often, so I was making progress)
I exposed the lines under the carpet in rear driver side footwell, and found hose with nothing attached. Some testing has shown that this is the feed hose to the pump (not sure why it draws air from inside the cabin), but after it cycles, it burps out this hose, and then cycles again. (Odd groaning/burping noise, coming out of this hose. I disconnected the hose at the pse (and blew and sucked through it confirming that this was the hose I had exposed inside the car), and now when the pump cycled, it simply let all the air out of the inlet fitting, and then cycled again.
I installed a new piece of hose with a check valve (not a MB check valve, actually one from a Seadoo) and this sort of solved the problem (now seat worked properly, but pump still cycled regularly (like once every 40 seconds).
First problem is the check valve might not have proper spec (in the Seadoo application, it isn't free flowing - it takes a few psi to suck on it, and this might mean that the pump is shutting off prior to coming to proper pressure.
The final question - is there a check valve somewhere in the feed line, or should the pump hold pressure by itself? Meaning, if I remove the feed hose, should it work properly, and is the fact that the air hisses back out after cycling the sign of a faulty pse unit?
Any other guidance is greatly appreciated.
-David
Initial symptom was odd groaning sound (intermittent) under rear driver side footwell, and lumbar and bolster functions in drivers seat was erratic.
I exposed PSE (left rear side of trunk) and found the primary feed line (from pse to black reservoir) was leaking. Replaced line, but problem remained. (alhough pump cycled less often, so I was making progress)
I exposed the lines under the carpet in rear driver side footwell, and found hose with nothing attached. Some testing has shown that this is the feed hose to the pump (not sure why it draws air from inside the cabin), but after it cycles, it burps out this hose, and then cycles again. (Odd groaning/burping noise, coming out of this hose. I disconnected the hose at the pse (and blew and sucked through it confirming that this was the hose I had exposed inside the car), and now when the pump cycled, it simply let all the air out of the inlet fitting, and then cycled again.
I installed a new piece of hose with a check valve (not a MB check valve, actually one from a Seadoo) and this sort of solved the problem (now seat worked properly, but pump still cycled regularly (like once every 40 seconds).
First problem is the check valve might not have proper spec (in the Seadoo application, it isn't free flowing - it takes a few psi to suck on it, and this might mean that the pump is shutting off prior to coming to proper pressure.
The final question - is there a check valve somewhere in the feed line, or should the pump hold pressure by itself? Meaning, if I remove the feed hose, should it work properly, and is the fact that the air hisses back out after cycling the sign of a faulty pse unit?
Any other guidance is greatly appreciated.
-David
12-27-2011, 08:07 AM
#2
I've got issues with my PSE system as well and it seems that you are progressing further into the system than anything I've read up to this point. Was wondering if you have developed/found any specifications on the operation of this system in your testing, prior to ripping into the system again.
Questions like, is this system similar to the W140 system where it supplies vacuum and pressure, or does it supply just a pressure value? What are the values of this pressure suppose to be? What is the acceptable leak down rate of the system?
In my case, the drivers door is cycling up to 7 times before the time out occurs, but there is definately a long cycle rate and the "thunk" noise is different sounding at the drivers door than at the rest. I really don't want to be replacing the pump only to find out its the handle causing all the grief.
Sorry to hijack the thread. Was not intending to. Just looking for information.
Tower
Questions like, is this system similar to the W140 system where it supplies vacuum and pressure, or does it supply just a pressure value? What are the values of this pressure suppose to be? What is the acceptable leak down rate of the system?
In my case, the drivers door is cycling up to 7 times before the time out occurs, but there is definately a long cycle rate and the "thunk" noise is different sounding at the drivers door than at the rest. I really don't want to be replacing the pump only to find out its the handle causing all the grief.
Sorry to hijack the thread. Was not intending to. Just looking for information.
Tower
