Mercedes W126 self-levelling rear suspension flush

I’m about to take my 560SEC on a road trip.    I’ve been making sure I had appropriate spares for this road trip, especially things that would he hard to get by the side of the road.   One thing on my list was some spare ZH-M.  ZH-M is the hydraulic fluid used in the self-levelling rear suspension.     Since I was ordering ZH-M I got enough to flush the 300TE and 560SEC, as well a a new filter for the 300TE.   The ZH-M was available from Sparesbox.

The fluid in the 560SEC looked fairly dark.  I last flushed it in 2019.   It seemed to take on this colour once the system was finally working properly.   In a previous article I outlined how a previous mechanic had the SLS lines reversed.   This resulted in low ride height.   I guess this was preventing flow, and therefore once things were flowing properly, any leftover debris in the system came through the fluid.   The picture above shows the old fluid.

I’ve covered the procedure for a W126 self-levelling rear suspension flush before, and it really is very simple.    The first step is to remove all the old fluid from the reservoir, and top up with clean fluid.

From there, I attached a clear hose from the return and put the end of that hose into a container.   In this case I used an old snow foam container.    Once this is ready I started the car and let the dirty fluid collect in the container.   The flow is low, so this job can easily be done with one person.

I also checked the filter.   It was a bit dirty so I changed it, and I’ll get a new filter for the 300TE.   Having a lot of debris in the system can mean a dead sphere.  I’ve driven a car with dead sphere and its really noticeable.    It doesn’t seem like one of my spheres is dead.

Once I saw clean fluid coming out as part of the flush, I turned off the car and then topped the reservoir up again.    Doing a w126 self-levelling rear suspension flush is a good simple job that is easy to do at home. The final photo shows the job complete and the reservoir topped up. ZH-M is clear, so the colour of the fluid should reflect that.