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94 - S500 Cpe
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Discussion Starter #1 (Edited)
My ’94 S500 coupe SLS Suspension was not performing as it should. Initially I found that the hydraulic fluid was low . . . and then a ‘leak’ from the right rear strut.

I considered REPLACING it with conventional shocks but saw a '05 S500 that had it done and it SAGGED just sitting there!!!

So lets see if it can be fixed . . . w/o spending a fortune. Here’s my “saga” of getting it repaired . . .

Hope you find it informative. https://www.k6jrf.com
/Suspension_Repair.html
 

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1999 S500; W140.051
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You must evaluate your commitment to the car. if the car is in good shape; runs well; interior is nice, etc...., Then it might make sense to fix the SLS suspension.

If you are a DIY'er capable of dealing with the springs, etc, then it's actually not a very hard job, but does require ~$1300 in parts. Since you DO have a leak at the strut, unless it's from the hose or joint at the ends of the hose, then that's as good/cheap as it's going to get. As long as the tandem pump at the front doesn't leak, then the strut & accumulator R&R is not too big a deal except for the cost of the parts. Doing such a job is really a commitment to about another 100k miles of driving as that's about how long the system lasts without needing some replacement.

You might even get the front shocks as well with the $1300. They are cheap; last as long as the SLS shocks and are also straightforward to replace.

If you had ADS, the cost doubles.
 

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Discussion Starter #3
You must evaluate your commitment to the car. if the car is in good shape; runs well; interior is nice, etc...., Then it might make sense to fix the SLS suspension.
That's exactly why I tried to SEE if it could be repaired rather than scrap it for either all NEW SLS parts or replace w/ conventional springs/shocks.

It appeared to be the right decision . . . bottom line w/ labor was $600. And the SLS system is as good as new!

If you are a DIY'er capable of dealing with the springs, etc, then it's actually not a very hard job, but does require ~$1300 in parts.
I seriously considered that but when I saw a 2005 S500 sedan with the changeover, it looked pretty sad . . . b/c it was drooping . . .w/o any load in the rear!! That changed my mind quickly!

Since you DO have a leak at the strut, unless it's from the hose or joint at the ends of the hose, then that's as good/cheap as it's going to get. As long as the tandem pump at the front doesn't leak, then the strut & accumulator R&R is not too big a deal except for the cost of the parts. Doing such a job is really a commitment to about another 100k miles of driving as that's about how long the system lasts without needing some replacement.
The great side effect of this job was the strut "repair". It appears, in my case, that the hydraulic fluid was "low" and that caused the seal to dry-out just causing a small leak.
With the procedure I used, the seal must not have been permanently damaged b/c it is not leaking now. In testing it, it's as good as the other non-leaking one. That is the main reason I've posted it here . . . this MIGHT persuade others to try what I did and get the SLS system operating w/o major cost.

You might even get the front shocks as well with the $1300. They are cheap; last as long as the SLS shocks and are also straightforward to replace.
The front shocks appear to be in good condition and don't need replacing. The "parking-lot" speed bump test will quickly tell you whether the accumulators are bad!
 

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1999 S500; W140.051
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I hope it works out well for you. You have to make repair choices judiciously. The W140 is a car that is so finicky about everything being perfect, especially with the suspension. Yet at the same time is a car that is very ruggedly built. It doesn't fall apart easily, but the possibilities of making closer to perfect are always there so it's best to take a balanced holistic approach on the repairs.

With the SLS struts there are a number of failure modes. The upper mounts; the lower mounts & lastly leaks. I think leaks are probably the least common failure mode.
 

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94 - S500 Cpe
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Discussion Starter #6
I hope it works out well for you. You have to make repair choices judiciously. The W140 is a car that is so finicky about everything being perfect, especially with the suspension. Yet at the same time is a car that is very ruggedly built.
I agree about the suspension b/c just ONE (1) bad accumulator seems to destroy the suspension's ride.

With the SLS struts there are a number of failure modes. The upper mounts; the lower mounts & lastly leaks. I think leaks are probably the least common failure mode.
I've read about the top and/or bottom failures (broken welds, etc) but not so much about leaks.

Again that's why I posted the thread . . and I'm not sure that I was detailed re the cost it takes to find out whether you can 'save' the strut; apx $25 . . . some Lucas SL, a gal of hydraulic fluid, a 4 ft piece of plastic tubing and an old pail. Follow the simple flush procedure, add the Lucas SL (12 oz) and drive the car. If it stops leaking, have a La Gloria Serie R #5 and some good scotch! That's what I had this afternoon.
 

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1999 S600 & 1999 S500
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I am going to check the fluid level in my S600 later today. Thanks for the write-up.
 

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Discussion Starter #9
I am going to check the fluid level in my S600 later today. Thanks for the write-up.
Yes, by all means . . . don't do what I did . . fluid level hadn't been checked in at least 5+ years.

Last year I think the car was driven apx 400 miles BION! So it just sat in the garage.
 

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Discussion Starter #10
I seriously considered replacing the SLS system with conventional shocks and springs but when I saw a 2005 S500 sedan with the changeover, it looked pretty sad . . . b/c it was drooping . . .w/o any load in the rear!! That changed my mind quickly!
I want to expand on this abit: I visited a local "suspension expert" shop and there was this '05 S500 sedan there. The 'expert' said . . never mind the accumulators, just replace the complete suspension w/ conventional shocks and springs. I replied that I've considered this but am hesitant about taking such a large leap.

The expert replied . . check out that S500 sedan. It's actually then that I fully noticed it and the sagging rear end. The owner of the S500 car was there. I asked him why is it drooping? He replied that "they" (ie, the EXPERT) put in MOOG shocks or something equivalent and some "springs". I've done a little homework, so I suggested that maybe Bilsteins would have been better. At that point, I KNEW that I wasn't going to replace my SLS system . . . and if I did, it wouldn't be done in this expert's shop!!
 

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1999 S600 & 1999 S500
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I am going to check th efluid level in my S600
I want to expand on this abit: I visited a local "suspension expert" shop and there was this '05 S500 sedan there. The 'expert' said . . never mind the accumulators, just replace the complete suspension w/ conventional shocks and springs. I replied that I've considered this but am hesitant about taking such a large leap.

The expert replied . . check out that S500 sedan. It's actually then that I fully noticed it and the sagging rear end. The owner of the S500 car was there. I asked him why is it drooping? He replied that "they" (ie, the EXPERT) put in MOOG shocks or something equivalent and some "springs". I've done a little homework, so I suggested that maybe Bilsteins would have been better. At that point, I KNEW that I wasn't going to replace my SLS system . . . and if I did, it wouldn't be done in this expert's shop!!
I thought the S Class switched to air bags starting in 2000. wouldn't that mean they had no accumulators?
 

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Discussion Starter #12
I thought the S Class switched to air bags starting in 2000. wouldn't that mean they had no accumulators?
I guess they did . . . I've never looked at the block diagram of the ABC system . . . but your post prompted that . . and is it complicated!!!!

Look at #14 (front wheels) and #4 (back wheels) . . .
2608234

I also see where StrutMasters makes a number of conversion kits, so it appears that the "expert" didn't follow this and designed a 'system' on his own?

Here's a link to BW thread on replacing the ABC system: here

And I thought the SLS Suspension system was complicated . . . :(
 

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'95 S600
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Sounds like they used the wrong springs\pads

I temporary installed a set of rear Lesjofors springs, Bilstein shocks and a lower spring pad, the ride height was identical to the SLS setup. Ride quality wasn't vastly different on the roads here, but the cars handling was noticeably improved. Too bad all the aftermarket sports springs and shocks are NLA or too expensive to ship here.
 

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Discussion Starter #16 (Edited)
Can we define how many bounces is considered "bouncy"?
Good question . . . nobody has asked that . . .

If it bounces even ONCE, replace the accumulators . . .both of them!

Press down on the back bumper . . get it moving up and down . . let go . . . it should come back to neutral.
 

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'97 S500 w/ Nappa "Leather Exclusive"
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Good question . . . nobody has asked that . . .

If it bounces even ONCE, replace the accumulators . . .both of them!

Press down on the back bumper . . get it moving up and down . . let go . . . it should come back to neutral.

Thanks, JimF37 - I have 1.5 bounces.

I'm now looking to check the fluid, but the dipstick won't budge, and I don't want to force it.

Is there a trick to pulling the dipstick? Maybe mine's seized ...

Thanks again!
 

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Discussion Starter #18
Thanks, JimF37 - I have 1.5 bounces.
That's too many . .

I'm now looking to check the fluid, but the dipstick won't budge, and I don't want to force it.
Is there a trick to pulling the dipstick? Maybe mine's seized ...
If you need a little leverage, use a large flat blade screwdriver, wedge it under the 'lips' of the dipstick and gently lift the screwdriver . . it will come out.
 

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That's too many . .
If you need a little leverage, use a large flat blade screwdriver, wedge it under the 'lips' of the dipstick and gently lift the screwdriver . . it will come out.

Thanks again, JimF37

Your information was very helpful.

W/ appreciation /
UnshavenChauffeur
 

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Discussion Starter #20
Conclusions: (from my web page). . .

It's been over one month since the leaking right rear strut was discovered and repaired. First Lucas SL was employed for two (2) weeks, then it was flushed out and replaced with normal hydraulic fliud. Now, a month from the start, there aren't any leaks from that strut.

The theory that the seals were dried out b/c of the low fluid appears to be correct and, even better, it appears that it has been fixed in my case. The cause of this was the failed accumulators; the hydraulic fluid was depleted when the bladders failed causing the overall hydraulic fluid level to drop. Since I hadn't driven the car much, the car sat there for extended periods causing the strut seals to dry out and then leak.

Based on this, I'm positive that this "repair" can be repeated so it's worth a try before scrapping the strut.
 
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