Arrie

I have searched these forums and googled spending hours trying to find an answer but no luck so I started this new thread. If there is an answer somewhere in the forums please point me to the right direction .

So, my multicontour seats stopper working. iCarsoft reads that the pump is overheating and shut down. Reason is leak in the system.

Took the trunk lining off to get to the pump and after pump cools down it runs again but air leaks out thru the pressure safety valve on the reservoir.

The obvious fix is to get a new reservoir as the safety valve cannot be purchased separately but then I thought that what if the pump does not shut off at set pressure like if the pressure switch is bad? With this thinking I measured the pressure the pump puts out and I get up to 30 psi.

So, does anybody know what the pressure should be as 30 psi sounds a bit high?

Arrie

No replies to this but for anybody interested I replaced the air tank that came with the new safety valve and the multicontour seats now work like they are supposed to work so the 30 psi pressure seems to be fine.

BenzV12

Nice to see you got it fixed by yourself

Arrie

Knowing the stealer pricing would probably be north of $1k I had to try.

As both seats went out at the same time it kind of had to be the air supply issue, i.e. the pump or the reservoir. It was the safety valve of the reservoir that failed and, of course, it cannot be purchased separately so I had to get the whole reservoir for $247+fax.

Again, an easy job after you figure out how to remove the trunk lining to get to it. Hardest part of the job is to get in and out of the trunk.

konigstiger

For future reference see attachments.

Arrie

konigstiger,
thanks for the very good documents. I actually found your post in another thread with the trunk paneling removal after some search so I was able to get to the pump/reservoir.

Then I removed the reservoir and pump without taking the holder for those out. The "ear" for the reservoir on the left top corner broke off when I tried to figure how to get it out after removing the right top screw but this was no biggie as I had to get a new reservoir for the faulty pressure safety valve anyway, but it showed me that the holder for the pump and reservoir has to come out to be able to fasten the top left screw.

I wonder if the safety valve is available in Germany for their local customers there as the valve comes off of the reservoir with squeezing two tabs and pulling it out? It certainly is made the way that it is easy to change if you have the part.

I was able to install the whole assembly without taking the rear self support out but it was tight to get it in. If I even have to do this again I will take that support out first.

Thanks again!

riv-stage 1

are these procedure's /pics from only certain years of w221? I have a 2012 with a passenger seat that faults out and quits....wondering if the rear shelf area is even involved in this model year?

konigstiger

Arrie

Your 2012 probably has exactly the same system as my 2013.

Are you sure it is only the driver seat that goes out? Mine was both so it had to do with the pump unit.

What mine did when I tried to change any setting it would not take the new value when I selected it. It just jumped right back to the value it had. It first seemed to be just the driver seat but after going thru the settings on the passenger seat it was the same.

kbob999

Check out this thread for a number of dynamic seat issues and fixes.
https://mbworld.org/forums/s-class-w...ml#post8152190

BTW - I continue to have Dynamic seat issues where they 'return to zero', but a stop and restart of the car usually resolves them.
They are not related to leaks (I have checked!) so likely software/hardware.

Arrie

How do you know it is not related to leaks? You can have a leak just like I had with the safety valve that leaks and causes the pump to cut off for temperature limit. At that point the settings freeze and you cannot change them. Some settings go to zero. My leak was just so bad the pump could not keep up with it at all. You may have a leak that allows the pump to catch up with the leak but too many running cycles overheats it and it goes out and then returns when it cools down.

And I could not hear the leak from the safety valve until I removed the lining behind the rear seat in the trunk.