How to drain the suspension hydraulics on my 1996 SL 600

[Jimmy G]

I was changing the dampers on my front shocks and needed to drain the hydraulics. So I went to my trusty Star service manual and pulled up the section on how to drain the system. The picture of the hydraulic controller is totally different than mine. I cannot find the drain cap they talk about on it. I disconnected the leveling control rod. Can anyone help me?

Does any one know were to drain the hydraulics for the suspension? I do not want the flud to spray all over me and my SL 600 when I remove the conecter on top of the shocks.

[chriswufgator]

I was just posting about this the other day. MB never updated the WIS for ADS-II, it continues to show ADS-I diagrams and instructions for the 1996+ cars. This makes it a REAL treat!

As to your question, you can't really "drain" it per se, but what you do is flush it similarly to the way you do the hard top hydraulics. ADS-II actually has two bleed points, one front and one rear, even though the WIS shows 5.

You cycle the suspension through an SDS system with the two bleed valves open, while one guy continues to pour in fluid. It's a recirculating system, so you'll know you have a complete flush once the clear fluid starts coming out of the bleed valves. By that point, you'll have also gotten the air and nitrogen-aerated fluid out.

On ADS-II the reality is that every time you replace a blown nitrogen sphere, you also have to change the fluid. The compressible nitrogen gas becomes suspended in the hydraulic fluid that's supposed to be uncompressible, and from an engineering standpoint it amounts to adding extra shock absorbers to your car. For years I wondered WTF was up with my hard-but-bouncy ride, and it turned out to be the fluid itself. So you're wise for changing it. FYI, to perform the complete flush and bleed, you need a LOT of fluid, I'd get at least 10 bottles.

[Jimmy G]

Originally Posted by chriswufgator

I was just posting about this the other day. MB never updated the WIS for ADS-II, it continues to show ADS-I diagrams and instructions for the 1996+ cars. This makes it a REAL treat!

As to your question, you can't really "drain" it per se, but what you do is flush it similarly to the way you do the hard top hydraulics. ADS-II actually has two bleed points, one front and one rear, even though the WIS shows 5.

You cycle the suspension through an SDS system with the two bleed valves open, while one guy continues to pour in fluid. It's a recirculating system, so you'll know you have a complete flush once the clear fluid starts coming out of the bleed valves. By that point, you'll have also gotten the air and nitrogen-aerated fluid out.

On ADS-II the reality is that every time you replace a blown nitrogen sphere, you also have to change the fluid. The compressible nitrogen gas becomes suspended in the hydraulic fluid that's supposed to be uncompressible, and from an engineering standpoint it amounts to adding extra shock absorbers to your car. For years I wondered WTF was up with my hard-but-bouncy ride, and it turned out to be the fluid itself. So you're wise for changing it. FYI, to perform the complete flush and bleed, you need a LOT of fluid, I'd get at least 10 bottles.

Can you tell me where the two drain points are at. I need to relive the fluid pressure so I can change the front shocks.

[chriswufgator]

Originally Posted by Jimmy G

Can you tell me where the two drain points are at. I need to relive the fluid pressure so I can change the front shocks.

Speaking generally, one's in the trunk and one's up front by the pump. But as to exactly where, I'm not sure. I quickly realized this system was waaaaaaaaaaaay over my head and another member here recommended a guy named Steve Brotherton who is a 40+ year head tech, who finally figured out the issues with my car were fluid-related despite the fact that A: Mercedes swears this is "lifetime" fluid and B: The WIS is totally wrong on ADS-II.

I had replaced several blown spheres and never changed the nitrogen-aerated fluid. They saved me a sample, and it looks like carbonated root beer, the gas appears permanently suspended in it. It's been 4 weeks and it still hasn't settled out completely. Obviously, under the 1000+ PSI in the system, it will NEVER settle out and will continue ruining the handling.

After learning all of this about the WIS being wrong and showing ADS-I in place of ADS-II, and about Mercedes running around telling people this is "lifetime" fluid, it became obvious why none of my local mechanics could figure my problems out. And don't get me started on the $tealers, I have a whole stack of "NO FAULT" reports they printed up. Idiots. Thanks again to Bobterry for finally recommending someone with the brains to do more than just plug in a computer.

Anyway, email SteveB@atlantic.net and tell him you talked to Chris Wickersham and that you also have an SL600 with ADS-II that you can't figure out. He'll be happy to take the time and fill you in, when he gets back from the bimmer tech convention in Colorado. I always try not to hold his love of BMW's against him, but it's tough. I always joke that he's not a prick, so why's he driving a BMW? I'm gonna get him one of those bluetooth earpieces and a big bottle of max-hold hair gel for Xmas, LOL.

[aam]

A master mechanic drives a BMW in staid then a MB?
Maybe he knows something that we don't?

Regards.
aam.