please take pictures of what you found and post them here!
WE LOVE PICTURES

Ok so I have an 82 300TD with the SLS and a bad diesel engine.

I bought a sedan engine. I was told that the "power" for the SLS pump comes from the head of the engine.

So how do I fix this problem so I can put the sedan motor in my wagon and still have a working SLS?

Swap the cylinder heads.

W124 SLS Issues
 

New member to forum, was really happy to see such a complete write up on W123 SLS. While the SLS is functionally similar in W124, are the leveling valves (and repair) the same? My '87 300TD SLS jacked the rear end up as for a heavy load, even though there was no load, after only 432K miles. I read your (Biodiesel300TD) troubleshooting guide, but didn't find a "rear end jacked up and rides like shocks are bad" write up. D you have a guess as to what my problem might be? Do you have a kit for W124 valve (if that's the problem)? Do you offer rebuild service? Thanks for your help, David E

Unfortunately the 124 valves are not rebuildable. They aren't designed to come apart like the 123 valves are. You can get to some of the o-rings but not all of them. If the rear is riding high all the time I'd look at the connecting rod between the valve lever arm and the sway bar. It may have become disconnected and so the lever arm dropped down, making the valve think the rear is sitting low so it's compensating. If this is the case your car is sitting at its max height and probably riding bad because of it.

Hello everybody,

I am new to this forum and found the "write-up" on this thread amazing. Thank you for sharing this information with the rest of us.

I have a situation that has begun to concern me. The self-leveling suspension on my 1991 Euro 190E 2.5 16V works perfectly and does not go down at all (even when leaving the car parked for 3 weeks) or leak. However, with the engine running this valve (PN: 123 328 0531) produces a "thump" noise every 3-10 seconds (frequency varies). I would like to know if anybody has experienced this condition/situation and if this is any sign of "imminent failure" of this part. Any words of wisdom would be appreciated.

Best regards,
Slfan1

Re: jacked up rear on W124 w/ SLS. You were exactly right about the connecting arm coming loose. I feel lazy not looking underneath before posting, but I was still full of turkey. The ball and swivel attachment at the valve has corroded and I won't be able to reattach, but the dealer ordered a new connecting rod for only $41. I don't think my zip tie is a long term solution. Such is the cost of driving a luxury vehicle. Thanks again for your help, David E

At least you knew what to look for when you climbed underneath.:D Glad I could help, and it was an easy fix! Happy motoring.

That part is the SLS valve. It's responsible for maintaining the level of the rear. I've never heard of the SLS valve making a thumping noise. Are you checking this while under the car with the engine running? If not I'd do that so verify that is it that valve itself and not something else. Does it do it while while sitting or when lifting or raising? If it is the valve I'd suspect that it is a sign that it's failing. Make sure the system is full of fluid. Unfortunately there isn't much you can go with those valves. A new one or a good used one is the only option if it is failing.

BioDiesel300TD,

Thank you for your answer. I had the car raised on a lift with the engine running and can confirm that the thumping noise is coming from the SLS valve. Any advise where I should procure this valve?

Thank you,
Slfan1

OK, we got the system to level the car but the ride is very bouncy and feels totally undamped.

Am I correct in thinking this is spheres?

Also is there any way to verify before installing them that used ones are good?

Sounds like the spheres (accumulators) to me. The only test I know if is to poke around with the eraser end of a pencil into it and see if you can find a tear.

In Brazil, do you have junkyards with Mercedes from the late 80's through the 90's? SLS came on a lot of models through that time era and they all used the same valve. All of the wagons through that time, and a lot of the higher end sedans had SLS. That would be the cheapest way to find one. I have an extra, but shipping might make it pretty expensive. You can buy a new one from Pelican Parts for $458. Otherwise you might be able to find one close to you on ebay. You can always get one through the dealership, but get out your wallet, and prepare to leave your arm and leg as well. :P You might also be able to find a shop that works on Mercedes, and they might have a way to get one for you a little cheaper than shipping if from the US.

Thanks Andrew!

The best explanation of knocking noises from the rear comes from the manual. Scroll down to page 5 of PDF attachment.

I have a good flow of fluid from the return yet, the rear will not raise when moving the lever on the valve. No external leaks but the tank was empty. I fear the pump is shot.

Is it possible to have a good return flow with a bad pump?

Flow with bad pump
 

Possible, but not probable.

R320
 

Hi, I'm new here and so far the amount of information I can see is amazing. Over the last week my 2006 R320 has started being lower in the rear in the morning. The ride is perfect and it raises when started. I'm assuming it's just the levelling valve? Is it repairable on the R Class? I don't have full airmatic suspension. If it is repairable what part numbers do I need?
John

Afew years late!
 

Ya I had to do this once... My girlfriend at the time had bad compression so she ordered a used engine... I specifically asked for a wagon engine and they assured me it was one.. got it and it had the wrong head!

If both engines are out of the car and on a stand its not so bad.. the hardest part of the job it timing the injection pump! If you do swap the heads at least you will have a new timing chain and head gasket.. but those parts are not common to replace...

Kinda fun...

Ya I am rebuilding my SLS right now... The previous owner put gas shocks in :eek: I am about to diagnose the SLS once all the body welding is finished,,, we are almost done cutting out all the rust and hand forging new metal pieces and welding them in ! It pays to have a blacksmith for a best friend!

I will try to post some pics...

I put new SLS Shocks in and new lines to the accumulators.. the system has been dry for 4 years! I will most likely need accumulators and a pump rebuild... I haven;t seen a listing for a supplier who sells the pump rebuild kits in this thread... Anyone know?

Thanks. wish me luck who knows maybe it will magically work!
:D

Uh, post 4?

size of the pressure hose under the body?
 

Hey all,

So I took the wagon off the stilts today and set her on the ground with the new SLS components... New SLS shocks (were missing when I bought it) new lines from shocks to accumulators.

The pressure line under the car body, the metal line that is about 5/16 in diameter, busted a leak and squirted all the hydro fluid out :(

Anyone know what size hose that is? The metal line that is about the size of a break line???

At least the pump seems to be working.. it built pressure!

valve configuration supply and return lines
 

Hey there,

So i am in the middle of replacing the metal lines under the car... the supply and return lines.. i found them to be six mm or quarter inch with the fittings slightly drilled out...

On the valve itself... is the supply from the pump the lowest fitting or the bottom fitting and the one just above it the return?

That is how they are set up on my car.. just making sure that it is right.. Searched for a while and cant find it on the forums... which one is which...

Thakns!

FSM 32-501 Level control system and inspections
 

FSM 32-5xx covers "Level control system and inspections"
FSM 32-501 is the "Functional Description" (Parts A-D; 16 pages)
FSM 32-501D covers the "Control Equipment" (3 pages)

I have attached FSM 32-501D for you. Hope it helps.

Better late than never. I looked this thread up this morning before changing both accumulators. Ride got so bouncy that it just had to be done. Was a little embarrassed to see one of my posts from 2010 regarding the sagging rear. Still sags a little overnight. ... will address soon enough but for now I'm happy to have my smooth ride back.

Those 11mm bolts on the hard lines were a bit of a problem. They looked like the threads were stripped. Must have been from a previous repair. I managed to get them to hold but not without a few walk away moments. Next time those lines are getting replaced i think. ..

I'd like to know if anyone has thought of a clever way to properly adjust the length of the control rod (between SLS control valve lever and the rear sway bar). The FSM calls for some special tools I'm not particularly inclined to purchase.

I've got an '87 wagon and the original rod ends rotted out. Purchasing just the new ends was far cheaper than getting an entire new rod.

I was just trying to adjust the level on my 85' wagon and the ends (little ball and socket things) were allowing so much play that adjustment had almost no effect. Where did you buy the ends?

Is there a way to tell if the rear not rising is a failed pump internally or the leveling valve? Both these days are $400.

I see fluid returning to the reservoir but there doesn't seem to be a volume test in the mb manual so how can I tell if the correct pressure is there?

On W123, it's just a turnbuckle. Any suitable wrench will do. One direction will lengthen, the other shorten.

SLS valve rebuild kit
 

the OP doesn't seem to be on this forum anymore, and the links to the repair kit aren't working for me. Pelican Parts has a nice article on rebuilding the valve, but no kit (only one for the pump). Does anyone know where to obtain one for the valve?

M####source.com has a kit. It's great and includes everything you need. just rebuilt mine last week.

From the MB Classic Center in California.

Yes! That is not the answer to my question: What is the correct length? The FSM procedure calls for some special tools, which Stretch could probably fabricate in 35 minutes with yardsticks and a laser pointer and an old jack, but I'm not nearly as clever and determined as he...

The length is the length. What matters is ride height. Measure on a flat surface. Then adjust the turnbuckle until it's right. Longer if it's low, shorter if high.

I'll tell you a trick I used to get it set in one shot, but don't come crying to me if you break your arm. Remove the turnbuckle entirely. Then rig a long stiff wire to work the valve manually. Start the car and work the valve. Once the ride height is where you want it, set the turnbuckle so that it snaps into place with no tension. Just be aware that the hydraulic system can lift or drop the entire weight of the car at scary speed. So if you try this, don't hurt yourself. You must figure a gimmick that will let you work the valve without having any part of your body under the car.

What is the correct ride height? 1987 300TD.

The issue is that setting the ride height too high will increase the hydraulic pressure that the control valve must hold, and that increased pressure will eventually cause the valve to fail if the ride height is set too high. New control valves are $$$, so I'd rather find the "too high" setting before I need a new control valve.

You're not going to blow out the valve, but I'll let that be. The ride height measurements should be in the FSM.

It is, and it is measured with special tools that I don't have. That is exactly the dilemma.

SLS valve reseal kit
 

Hi all

Does anyone know where to obtain just the seal kit for the sls valve? Don't
need the more expensive complete overhaul kit.

Regards