Enigmatic SLS behavior

[Tempur]

I've asked about this issue on a general W124 forum before, but I’m hoping to find answers here from SLS experts. My early 1992 A124, which has the optional SLS, generally works fine. The rear doesn’t sag, and the suspension isn’t stiff. However, the hydraulic oil reservoir occasionally overflows. The level usually stays steady for months, then suddenly, without any apparent reason, it overflows.

After enjoying the car for months, I left it in my garage for two weeks without moving it. This morning, I found a puddle of oil underneath. I cleaned it up, but the next morning, more fluid had leaked from the top of the reservoir. So far, I estimate 2 oz must have escaped.

Can anyone here shed light on what might be causing this?

Thanks, Tempur

 

[gsxr]

First question - is the fluid level correct in the reservoir? Have a photo? On the 500E, the reservoir is only about half-full when fluid level is at MAX. To overflow that reservoir would take a significant amount of fluid (like, 0.5-1.0 quart/liter). The A124 uses a different reservoir, and I'm not sure how much fluid it would take to go from MAX level to spilling out of the reservoir.

Anyway - I've never heard of a problem like this. How old are the nitrogen pressure spheres / accumulators? It almost sounds like fluid is being forced under pressure to the reservoir, although I don't know how or why. Could be something funky with the level switch. @Klink - any ideas?

 

[Tempur]

Hello @gsxr, thanks for the reply. The A124’s hydraulic reservoir is filled to about two-thirds, which is the maximum level. After the first overflow in early April, a nearby MB specialist checked the system for leaks and refilled the reservoir. The level remained stable until yesterday morning, when it overflowed again. My only conclusion is that the accumulators are releasing pressure back into the system, causing fluid to return to the reservoir and overflow—but I don’t understand the mechanism behind this.
Tempur

 

[nocfn]

If there is a chance that the sphere (s) are original, perhaps a nitrogen accumulator sphere has an internal rupture, and is full of fluid., and so is the system. Also at temperature after a good drive, look at the soft hoses for bulging. If there is a rupture of the sphere bladder and your system is overfilled, you may not notice it per se, especially if the reservoir was perfectly full or over full. On my C126, I never bounced or sagged with a rupture, I was just hard ride and my level seemed high. Also when my hose popped, it was like an autopsy. The high pressure hose the first time and the second time it was the accumulator hose. What a mess. The 124 gave me a bouncy ride like a clown car as the dampening bladder was blown so my level filled the sphere and I bounced without dampening. The nitrogen bag can leak over time and fill up with fluid slowly, and you add it normally to the point where it is just a full system and one sphere is doing all the work, especially if you do not dirve it daily for 20 mile or so each trip.