Any input would be appreciated. My 03 SL500 has 69,000 miles on it. Have owned it for 5 plus years. Am a stickler for maintenance. Have flushed the ABC system every 2 years and had to replace one rear shock 4 years ago. My car had been sagging over the last 2-3 years, usually the right side and mostly the right rear. This past summer I did a flush, filter change and rebuilt the valve blocks, front and rear. They and the rubber o-rings looked in pretty good shape but replaced them and lo and behold, when I started the car afterwards, bled it, it rose up right away. The sagging problem has gone away. It might settle a 1/16 of an inch per day but even on all corners. Yeah, I'm happy. But I did notice a couple times when I hit a big bump or rough rail crossing the red "ABC failure" light flashed on for maybe 2 seconds but then right out. Car road fine, didn't notice any stiffer ride. A month ago I left to head south for the winter, got the red" ABC failure" light after 45 minutes, again another 45 minutes later and then right after that it stayed on steady. Pulled over, the fluid had backed up thru the overflow pin hole on top of the tank. This has happened a couple times before. Check the fluid level while COLD, it stays right above the top mark and when running was just below the "running" mark. Why would excess fluid back up into the tank and overflow (just enough to get things messy). This time 110 miles from home the same problem, only the car felt like it was wallowing down the road. The fluid was just below the "running" mark when I stopped, added 1/3 of a quart but there was no way to make the ABC Failure light go out. Turned car off and restarted a couple times to no avail. Backtrack home and changed cars. My question to anyone with a similar problem? Accumulators? I've read that when they go bad they fill with fluid, the gas escapes and the right gets rougher? I will not be home for a couple more months, have stopped at a M-B dealer down here to pick his brain to no avail. Maybe it starts right up, rises up and works fine, probably not! Any idea of why the light flashed on for a second or two when hitting a railroad track? And idea of where the excess hydraulic fluid is coming from that it overflows the tank when it is at the correct level when cold? Probably will have to drive it to the M-B dealer when i get home and get it on the STAR for diagnostics. The good news is that it road home loaded with probably 150 lbs. of stuff in the rear and the back held up ok and the front had only lowered 1/2 inch in the 110 mile drive. Sorry for the log post but this forum has been very helpful in the past and was hoping someone else might have has a similar issue? Thanks

 

I believe the gas can escape slowly to the point where the accumulator has failed, its diaphragm is intact, and it does not fill with oil. If they do fail, the ride quality is generally unaffected. Where you might notice a difference is when traversing speed bumps or anomalies in the road surface which are similar.

An ABC fault indication flashing when you traverse railroad tracks leaves no doubt that the front and/or rear accumulator have failed. Star Diagnosis (SDS) is the only diagnostic system which can identify which one. You can put together your own SDS for as little as $250.

 

By "these guys" you actually refer to a single individual -- yourself.

Visit "××××××××?'s" website at your own risk. A moderator found a trojan virus on it, but I learned too late: my browser now acts strangely, and I believe my PC is infected.

 

Does your car still raise/lower with the center console switch?

 

Mods need to clean up these fake accounts, this is ruining the forum experience.

We need each other’s help with these cars and people are going to stop coming back here if this crap doesn’t stop.

spam post reported to mods.

 

In short, it is possible for the ABC fluid to get by the deteriorating membrane.
Just replace it before it breaks completely and contaminates the system.

Here is the link to my personal experience with ABC accumulators;
https://mbworld.org/forums/sl-class-...umulators.html

 

It's my guess that not only is this possible but that it is nearly always the case.

 

No, would not after the red "ABC failure " light went on. Didn't drop a whole lot in the 110 mile drive home but the front dropped more than the rear.

 

Good post MarkCan, think mine is now doing the same thing. Will change them out when I get back up north in the spring.

 

Probably accumulators. Mine did the same thing when I went over bumps/pot holes. Replacing the accumulators and doing a valve block rebuild eliminated the warnings entirely.

 

Got back up north 2 weeks ago. The front end was sagging but the back still up. Rebuilding both valve blocks worked. The excess fluid had dripped from the body onto the garage floor. A couple things I noticed. One, the fluid in the tank had what appeared to be thousands of very tiny bubbles, you could see them both when checking the fluid level and when I removed to return line. Topped off the fluid, started the car (3 months after the failure) and low and behold, the car raised right up. The red menace warning was gone. Ordered new accumulators and had then 3 days later. What I found (and I've seen one other post that said the same) was that the rear accumulator, 4.66 lbs weighed two ounces less than the new ones 4.9 lbs.(original Mercedes vs Corteco) Manufacturing differences. But the original front one weighed 5.6 lb. A full 15.5 oz. more. The membrane wasn't broken at the top point ( a narrow screwdriver only goes in about an inch, not drops to the bottom of accumulator. Left both old ones upside down for the 3 days and got next to no hydraulic fluid out of them. So it's pretty obvious that hydraulic fluid can force it's way thru a compromised bladder. And where did the nitrogen go? Back uphill thru the valve block and back to the expansion tank. Hence the thousands of tiny bubbles i originally saw. After installing the accumulators I bled the system, changed out the filter and so far so good. Even tried to hit the railroad tracks harder to see if it would trigger the red menace. None so far! Perhaps after rebuilding both valve blocks last fall where you have to remove the accumulators from the valve blocks, when you put it all back together the initial rush of hydraulic fluid towards to bladder caused it to rupture, filling the front one with fluid slowly and displacing the nitrogen back to the tank. Doing the bleed and rodeo cleared up the bubbles in the tank. Now just clear fluid as before this mess started. Hope this helps anyone who encounters this problem in the future.

 

New accumulators, valve block rebuild, and fresh ABC fluid did wonders for my SL. Not a single ABC error since. Glad to see it's working for you too!