Repairing the Self-Leveling System

An article written and kindly provided by Brett Allison  

Note that this was written using a 1997 S600 as the subject car.  It may or may not apply to other years!

DO NOT WORK UNDER YOUR CAR WITHOUT PROPER SUPPORT!
AT A MINIMUM, USE SUITABLY RATED JACK STANDS OR RAMPS!

Rare failure.  Broken self-leveling valve linkage.  And fixing it.

My brake wear light finally started coming on the other day, so I took my wheels off to inspect the brake pads.  I was actually pleased that the pads went more than 30,000 miles on such a heavy car.  They still have a couple thousand miles left.  But, I digress…

The moral of this story is to always keep your eyes open and give things that you don’t normally see a quick inspection any time you have ample opportunity to do so.  When I had the wheels off, I was poking around under the wheel wells as usual, and this is what I saw:

The linkage arm between the valve for the self-leveling rear suspension and the anti-roll bar had broken off and was resting on the inner CV joint boot of the left side half shaft.  I don’t know how long it had been broken and riding on the CV joint boot.  Fortunately, it doesn’t appear to have caused any damage to the boot.  The linkage arm is attached by ball joints at each end.  They have a metal ball in a plastic housing.  It looks like the plastic simply broke apart due to age, and the linkage arm just fell off the ball.  I didn’t notice anything amiss with the ride height of the car.  As I was working on it, I cycled the hydraulic struts through their complete range of motion, and it seems like the normal ride height is pretty much as low as it will go anyway.

So, on to the repair.  Should be quick.  Right?  One nut and two bolts, and I already soaked the fasteners for a week with liquid wrench due to the corrosion (see pic below).  Not so fast.  The working space is so tight, it took me around an hour to get the damn nut off that attaches the ball joint to the bracket on the anti-roll bar.  Good thing I’m skinny.  No fat fingers allowed.  Then when that is done, removing the bolts from the valve arm is a pain because the valve arm will simply spin with the wrench, so you’ve got to get creative with counterholding the arm.  First the tools:  three 10 mm wrenches (1/4 in drive socket, regular box end, and a ratcheting wrench (very nice for the tight quarters)) and an extra skinny 8 mm open end wrench at the bottom of this pic. 

I don’t know why I have this wrench.  It’s in a set of Craftsman metric “ignition wrenches” that I’ve never used.  I think my dad gave them to me years and years ago.  Here is why I think the skinny wrench is important.  This pic shows just how skinny the skinny 8mm wrench is versus a regular 8 mm wrench.

And, the pic below shows the wrenches fitted onto the ball joint for counterholding while you would remove or install the nut on the stud.  This pic is of the old destroyed ball joint (missing the plastic housing).  You don’t want the wrench to be much thicker than the flange of the ball joint otherwise the plastic ball joint housing will be severely deformed during installation.  In my opinion it may damage it.  So, I thought the skinny wrench was important to do this job right.

Here are the old and new parts.  This is what a few New England winters will do to the underside of your car.  My car spent 6 or 7 winters in New Hampshire.  I adjusted the new linkage to the same length as the old.  The ball joint on the left end is the one that failed.

Here is the new linkage fitted in place (not tightened down, yet). 

Like I said, getting to that nut that you can’t see on the ball joint where the arm attaches to the anti-roll bar is not easy.  It takes small hands and a few choice swear words to do it.  The 10 mm ratcheting wrench worked great for installing the nut.  It was removal that was a royal pain.  Here is a pic showing the skinny 8 mm wrench in place to counterhold the ball joint.  Again, very tight quarters.

And once the linkage is free of the anti-roll bar, there is no longer anything holding the valve arm, so you have to figure out how to hold the arm while you undo the two bolts.  I got the lower nut off, then used a coat hanger stuck through the bolt hole to wire the arm to the frame of the car so the arm wouldn’t move while I removed the second bolt.

The nut on the ball joint is a self-locking nut.  Technically, it should be replaced with a new one.  I didn’t feel like going back to the dealer so I used blue Loctite on it.  The two bolts on the valve arm had blue thread lock material from the factory, so I cleaned them off and reinstalled with more Loctite.

Cheers.  I don’t know why I spent so much time writing this up.  I doubt anyone else will have to do this repair.

Brett

Many Thanks go to Brett for this fine write up!

Click here to e-mail Brett

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