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Discussion Starter #21
Well AG129,

Opposite to your upper encircled "S" is a grub screw with 3 mm allen head. In this channel there is one of the three check-valves the sliding valve actuates. This specific S-channel valve provides oil pressure for the height control rods, front & rear. My hypothesis is that you could have dirt/sludge in this valve. It cannot be disassembled but you can try move the check-valve by pressing with thin wire from both sides until the valve moves freely, maybe 1-2 mm. Sorry to say, to do this you must disassemble your ADS1 main control valve.

See also Jon Bearpark's drawing in this thread. Also, see this picture.

Hope I managed to clarify…?
Thanks Pazo

Yes that does make things more clear for me to understand. Unfortunately I won't be able to tackle this until next Thursday. So I have a week to study the old spares I got and hope when I take my unit apart that it finally works out as intended.

Manhunt, yeah I watched those videos of Citroens running around on three wheels or changing tires without a tire jack, very impressive. I do understand their ADS is tuned for a very different purpose.

I realized that with time the comfort mode is becoming slightly more forgiving or comfortable if that makes sense. Yes now the difference between comfort and sport is very noticeable, maybe the car needed to be driven around some more to self-bleed.

I have the AMG monoblocks with:

245/40-18 Michelin PS4 on 8 inch et31 wheels in the front and 20mm H&R spacers bringing my offset down to et11

275/35-18 Michelin PS4 on 9 inch et35 wheels in the back with 25mm H&R spacers bringing my offset down to et10

The spacers are a bit aggressive and require fender rolling, but the widened track actually made a difference to handling a bit even before restoring ADS

With ADS on sport, the car feels so planted and it keeps pushing you to try and find the limit of grip. I love how the car feels on sport mode.

On comfort mode the car is much more lenient and allows more body roll and generally makes you feel less bumps on the road but only to a certain extent. As you said, I think comfort mode would work best with the original 16 inch wheels with big sidewalls.

Too bad we can't drive on three wheels like the Citroen 😋
 

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Mahunt, AG129,

You may find interesting, how Mercedes salespeople were instructed to describe ADS1 advantages. It was standard in SL600 when it arrived. ADS was optional in other models and added 5% to the 500SL base price tag - even more to the 300SL. However, the speed-dependent height control was not sold in the US. ADS1 was replaced by ADS2 from Sep 1995.

A Dutch collector has uploaded huge selection of Mercedes brochures in his website "oudemercedesbrochures"; the attached extract is from there.
 

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Discussion Starter #23
Mahunt, AG129,

You may find interesting, how Mercedes salespeople were instructed to describe ADS1 advantages. It was standard in SL600 when it arrived. ADS was optional in other models and added 5% to the 500SL base price tag - even more to the 300SL. However, the speed-dependent height control was not sold in the US. ADS1 was replaced by ADS2 from Sep 1995.

A Dutch collector has uploaded huge selection of Mercedes brochures in his website "oudemercedesbrochures"; the attached extract is from there.
The image you uploaded is broken, it won't load.

What I find weird is why they differentiated between the Euro spec cars and the US spec with the height control option.

I think it might have something to do with bumper height regulations or light regulations in the US, but I'm not sure.
 

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Discussion Starter #24
Mahunt, AG129,

You may find interesting, how Mercedes salespeople were instructed to describe ADS1 advantages. It was standard in SL600 when it arrived. ADS was optional in other models and added 5% to the 500SL base price tag - even more to the 300SL. However, the speed-dependent height control was not sold in the US. ADS1 was replaced by ADS2 from Sep 1995.

A Dutch collector has uploaded huge selection of Mercedes brochures in his website "oudemercedesbrochures"; the attached extract is from there.

I can actually see the brochure you uploaded now. I think it's due to the new format of the website.

Anyhow. I finally fixed the oil leak in my ADS. Took the tandem pump out and changed all the seals. The front regulating rod was weeping too and we dismantled that from info and pics from the other thread you sent me. The electronic module (name??) that attaches to the ADS distributor had some seals that needed changing as well. Now there are no leaks whatsoever.

However, before changing the seals. We tried pressing the raising button and I can confirm both front and rear regulators were extending but the car was not raising. This happened by itself though, I guess the car self bled more or cleared a blockage in the channel.

However, after replacing the seals, both front and rear rods are not responding to the level switch being pressed.

I suspect that the channel marked "S" that sends oil to the front and rear rods has a blockage somewhere. When the rods were working before, maybe it was low oil pressure due to blockage and now it seems it got completely blocked again.

I'll take it apart again and try to clean it again and bleed it again and see if it will finally work.

Do you have pictures of what you described here?

"Opposite to your upper encircled "S" is a grub screw with 3 mm allen head. In this channel there is one of the three check-valves the sliding valve actuates. This specific S-channel valve provides oil pressure for the height control rods, front & rear."

It would help me identify it better and figure out how to clean it as you described.

One more thing I noticed, after reinstalling the tandem pump there was some whistling noises during the bleeding process. This is described in the bleeding process when you have to bleed the pump. It goes away after bleeding and driving the car around.

I also noticed that the sport/comfort switch has a less noticeable difference after reinstalling the pump. However, I experienced this when I first installed the system and it was only after driving around that the difference started to become bigger and bigger. Perhaps it's an adaptive thing that takes time or needs the car to be fully bled by driving some more.
 

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Most likely it needs to be bled further.

Unfortunately, the (possibly) easiest way to bleed the system is to use the up/down rocker while waiting at stop lights.

Not that I can tell, but one of the "features" of the ADS system is to lower the car for fuel economy reasons at higher speeds. When the car reaches 118 km/h it lowers 15 mm and doesn't raise back up the normal resting height until the car slows to 111 km/h.

The full MB reasons are:

Lower center of gravity
Lower air resistance
Less lift at the front axle
 

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Discussion Starter #26
Most likely it needs to be bled further.

Unfortunately, the (possibly) easiest way to bleed the system is to use the up/down rocker while waiting at stop lights.

Not that I can tell, but one of the "features" of the ADS system is to lower the car for fuel economy reasons at higher speeds. When the car reaches 118 km/h it lowers 15 mm and doesn't raise back up the normal resting height until the car slows to 111 km/h.

The full MB reasons are:

Lower center of gravity
Lower air resistance
Less lift at the front axle
Yeah I saw that in the brochure that pazo uploaded. It's very useful and describes ADS in such a detailed manner.

I can raise and lower the car manually using the front and rear levers on the leveling valves. I just need to figure out what's blocking oil flow to the regulating rods so that they can extend and push the levers up and down respectively.

I'll open up the solenoid again and try to locate the S channel valve and clean it to make sure oil flows properly to the regulating rods. Then I'll re-bleed the system and hope for the best
 

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Discussion Starter #27
I completely removed the front ADS main distributor and replaced it with a 2nd hand unit that I cleaned thoroughly.

I opened up the y36 solenoid as much as I can and replaced all seals and cleaned it thoroughly using AC delco carb cleaner and a metal brush and I used compressed air and checked each port and channel and they all blow through perfectly

I opened up the grub screw and used the carb cleaner and compressed air. I couldn't take the piston out as I didn't know how but I tested both the three wire plug and the two wire plug with a 12v battery. They both give a perfectly audible click.

I replaced the front leveling valve with a second hand unit that was refurbished due to a leak. The first unit was not allowing the car to lower when lowering the lever by hand during the bleeding procedure.

After all that crap, this thing still doesn't lower or raise when pressing the button. You can still hear the click when pressing the ride height button by the headlight switch but both front and rear regulating rods don't extend at all. However, they are not seized as they move by hand.

If I unplug both hoses that connect to the front regulating rod as the car is running, what should I observe? Should they spill oil in normal operation or only when the ride height button is activated? This is to test if it's a matter of block or poor oil flow to the regulating rods.
 

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If I unplug both hoses that connect to the front regulating rod as the car is running, what should I observe? Should they spill oil in normal operation or only when the ride height button is activated? This is to test if it's a matter of block or poor oil flow to the regulating rods.
I have not tested myself the height control rods this way but I believe oil will come out, engine running and elevated height selected, from the flexible oil line marked on rod with red paint. Otherwise, little or no oil should come out. The pressure comes from front spheres and is shared with both front and rear regulating rods.

I have run out of ideas, what could be wrong in your height control. Seems you have checked everything...
 

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Discussion Starter #29
I have not tested myself the height control rods this way but I believe oil will come out, engine running and elevated height selected, from the flexible oil line marked on rod with red paint. Otherwise, little or no oil should come out. The pressure comes from front spheres and is shared with both front and rear regulating rods.

I have run out of ideas, what could be wrong in your height control. Seems you have checked everything...
Yeah I'm running out of ideas too, I guess I'll get a couple of used y36 solenoids and keep trying. I'm convinced it's something that's blocking the oil flow as the electrical side seems to work fine. You can hear the click clearly.

I don't know, I'll post here if I get any results.
 
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