Congrats on the SEL
To answer your questions, the job is Easy.. hardest part is getting the brake line style hydraulic fittings to line up... That aside it a 45-1hour a side job for a newbie.

Don't know of any tutorial.. Jack up the car, remove the rear wheels, undo the hydraulic fittings (be prepared for oil to go All Over..) Undo the 3 nuts holding the accumulator and swap in the new ones.

The accumulators you see on ebay are crap (btw, there are LOTS of non 126 part numbers cars on your car)...you couldn't pay me to install them in someones car.. If you plan on keeping the car use Genuine accumulators..they are the Only ones that have worked perfectly for me every time.

If you are something of a budge get Lemforders..I've only had one out of a pair go bad in reasonably short order.

The Febi/Cortecos are horrible IME.

Jonathan

 

560 SEL Accumulators

Thanks Jonathan,

I will do this myself. I found the Genuine OEM parts on

http://www.mercedes-benz-parts-direct.com/epc-items.asp

They are $126 each.

I probably won't get to it until after the 4th but I will let you know how it goes.

I checked out some of your videos...pretty cool stuff


-David


www.blackandwhitecookies.com

 

haha your cookies look good. let me know when the store opens.

 

Sure, I'd be glad to. Having since picked up the service side of the business full time I have had two sets of cortecos return as comebacks.. One set was on my white coupe...the other a nice 88 SEC that I take care of. Since then I have installed nothing but genuines with fabulous results. The corteco's last long enough so the warranty is not longer an issue (1 year) but I much prefer 100K of service over 15K.

Hope that clarifies it for everyone

Jonathan

 

560 SEL Accumulators

Thanks Guys.

I think I may spend the few extra bucks as I don't want to do it again.

One more question about the process...I have heard conflicing opinions on this.

Will I need to bleed the system after I install the new accumulators?

I have heard that "it is a self bleeding system"

I have also heard that you need to bleed it from a vavle in the front and a valve by the reservoir upfront.

Any advice?

Thanks,

David


www.blackandwhitecookies.com

 

I personally would go for the OE accumulators. On this system in the car, it's a messy job and the few extra bucks to ensure that you don't have to do it in a year or two is a comfort to me. The other parts in the system can run pretty high and the ride is the key to these cars.

Regards,

 

Quality aftermarket is becoming a tougher dig as of late..hell, Genuine isn't even a guarantee of quality anymore.

I know it's been a while since you worked on these cars so perhaps times/conditions have changed.

The systems are self bleeding. There is a bleeder (same as the brake bleeder) valve on top of the proportioning valve but I have never had to use it.

Jonathan

 

Congrats on the SEL


The accumulators you see on ebay are crap (btw, there are LOTS of non 126 part numbers cars on your car)...you couldn't pay me to install them in someones car.. If you plan on keeping the car use Genuine accumulators..they are the Only ones that have worked perfectly for me every time.

If you are something of a budge get Lemforders..I've only had one out of a pair go bad in reasonably short order.

Is Lemforder not the OE manufacture for the accumulator? I was led to believe they are.

 

That bleeder is to let the pressure out of the system before you remove any lines

 

The bleeder is also required to remove air from the system after refilling the system if it is drained at any point.

Having just retro fitted the entire system to my 560 SE, I can tell you you need to use that bleeder once the system is re-filled with oil. I transferred the system to my SE from the donor 560 SEC and all the pipelines, control unit, and struts were completely empty of oil.

Not sure how the sytem is self-bleeding - apart from that bleeder valve there is no where for air to escape from the pump onwards. And if you have just freshly fitted the entire system as i did, then you will have airlocks in the system....and they are only released using an 11mm spanner to open that bleeder valve on top of the level height control unit.


talbir

 

Interesting, every change I've done when I let the car down to take it for a test drive I can hear air excaping.
I have never had to use the bleeder on over 20 accumulator changes..I beleive I even read in the WIS that the system is self bleeding.

Edit:
Just did a bit of digging in the WIS and the bleeder is there to drain fluid prior to serivce, not for bleeding off air.

The procedure for re-filling the system according to MB does not involve the bleeder on the proportioning valve.



Jonathan

 

Where would the air escape from ???

Because where ever air can escape from, fluid can too....unless it's a special device somewhere that only lets out air but not fluid.

And I would really like to know where that device is.....because there is nothing external to the pump, control unit, accumulators and struts. Unless you're telling me that one of these has that clever device built in.

Accumulator changes won't allow much air in at all, so i'm not sure where you are hearing the air escaping from - I'm referring to full drainage of the system, or a strut change. There you would have a significant volume of air in the system.

With an accumulator change you won't know about it, it's so minimal.

It's basic physics - you fill an empty closed loop system with fluid, there will be air somewhere. Now if the SLS system does not have an automatic bleeding device, then how do you release the airlock ???

And why would MB build a bleeder valve on top of the control unit ? You can release the fluid pressure in the system by simply releasing half a turn on any one of the 2 upper union connections on the control unit ! The lower two connections are the feed and retrun pipes - the upper two are the feed/returns to the accumulators/struts, and that is where the pressure is.

So I'm keen to find out where this automatic bleeding device is.


talbir

 

The air escapes from the return line into the reservoir (it's not a closed system)..it's an open end for it to readily escape as long as the pump is half way decent.

During an accumulator change I run the car till the reservoir is Almost dry in an effort to get out as much of the old fluid as possible before flushing once the job is done.

When I get back home I'll gladly post a capture from the WIS. They state that you should hook a hose up to the bleeder and drain the system of it's fluid that way prior to working on it or to flush the fluid.

I just rang a good friend who was trained in Stuttgart back in the 70's and he was taught the system is self bleeding..

Jonathan

 

Not closed ? !

So where's the escape channel for the air on the reservoir then ?

The air will not be in the return line channel, rather the pressurised accumulator strut line channels.

Because if there isn't an escape channel (and I haven't seen one) then the air must sit in the reservoir right....

Running the car until the reservoir is dry doesn't flush the system - you've still got plenty of oil (the bulk of it in fact) sitting in the struts. If you think you have drained the entire system, then the new fluid you put in should be clean with no colour. If the fluid is dark colour in the reservoir, you've not quite done the job.

You'll have a little air in the system when you do an accumulator change - when you empty the struts you're not going to get away without bleeding the air.

What your good friend was taught is all well and good - but nobody has explained where the self bleed valve is, or where the locked air escapes the system. You need to define how the air escapes the system and why there is a bleed valve built on top of the ride height valve ???

It's not just there to drain the system - if your theory about releasing airlocks at the reservoir end was right, then you could run the system and drain it all at this end. But that's not how the system works.

If someone tells me something, i like to question it and understand it, rather than just accept it without understanding.


talbir

 

I did some more research, both in the WIS and in the Service CD as well as in my W126 chassis books. The Only use that is listed for the bleeder valve is for bleeding off fluid when doing a drain and fill as is shown here:
http://jono.mbfans.net/sls/drainandfill.pdf

Here are the other files I could find on having anything to do w/ removing and re-installing major componentry in the SLS system
http://jono.mbfans.net/sls/levelcont.pdf
http://jono.mbfans.net/sls/springstruts.pdf

Now where in any of these documents is it stated that one is required/needs to bleed the air resulting from the R&R out of the system; something that they make abundantly clear in any of the brake R&R documents.
Even in the PS section they state that pains must be taken to ensure all the air is purged via full lock to lock turns w/ a few seconds of holding against the stops.
Never is any such thing made mention of in regards to the SLS system.

The time I had one of the systems fully drained i.e., the reservoir, high pressure hose, both stuts, both accumulators and the proportioning valve, as well as the rear of the car kept lower to allow the drains to drip we put the car back together w/ the seats and chassis plugs out.
Upon leaving the shop we drove through a development that is ripe w/ speed bumps. Over each bump a Readily audible "Hiss" could be heard. This stopped after about a minute.

I personally have never looked for a bleeder as those who were in the know, ie Mercedes and their service literature never stated that the system needed to be bled. Upon asking those who have been @ this longer then I have been alive told me the same thing....
Having heard the same thing from Mercedes I didn't disagree/ask them to prove it by showing me how/where the air is bled from.

When I run the car until Almost dry (MB clearly stats the pumps should Never ben run dry as the hyd. fluid is what also provides lubrication to the pump) I do so to get the majority of the dirty fluid out.
I then finish the process by hooking up an external line/catch to the low pressure return and run fresh fluid through the system (usually while having someone simultaneously bounce the rear end up and down) until the fluid coming out of my return is clear. This will typically take a gallon/gallon and a half (I use John Deere hyd. fluid in my cars).


Jonathan

 

This is a good discussion. About how many quarts of fluid are needed to refill the system?

 

Sorry, but my questions remain unanswered, namely :

(1) where is the air released from if it is self-bleeding ?

(2) Why is there a bleeder valve if it is self-bleeding ?

To expand on point 1, you first said that the system release it's air into the reservoir. You then said that you can hear hissing sounds when you drive the car after system maintenance.....so where is the air actually being released ? Please don't tell me you can hear the hissing sound of air being released into the reservoir whilst the engine is running and you are sitting inside the car....

Where is this magic self-bleeding valve that everyone keeps telling you exists ?

Why do you simply believe it does exist when no-one has yet defined where it is in the system ?? Just because someone has worked on the system for 50 years, it doesn't imply they understand the system. They may have been taught a number of steps to go through and are just turning the handle without understanding the algorithm.


(2) How many of the other fluid systems on the MB cars have a bleeder valve ???

Bleeder valves are there to release air as well as depressurise.


Furthermore, your description of flushing the system isn't right. Bouncing the rear of the car up and down does NOT release the fluid out of the struts. The strut carries a good 5-6 inches of fluid - when you bounce the car up/down at the rear, you will be luck y to get more than 1 inch of travel either way. The only way to drain the struts is either to remove them and drain them by compressing fully, or remove the union connection at the accumulator, then let the car drop at the rear as far as it will go. With no strut supporting the spring, the car will sit down quite low at the back.


Just because MB literature does not talk about bleeding the system, it does not mean it is not neccesary. MB literature also does not talk about renewing the timing chain at 100k miles....so does that mean it's not neccesary ???


MB literature only tells you what is safety critical - i.e. you need to remove the air from the braking system as it won't function properly without it. It's a safety issue. Same for the steering. But the rear SLS system is not safety critical and the air won't have a massive impact on the system. But if you are not bleeding the air after maintenance, the job's not complete as the system won't be funtioning as well as it should.

To be consistent with your line on MB literature and MB guidelines , why are you using non MB fluid in the system. MB clearly states that only MB fluid should be used in the system ?


If someone can tell me how it's self-bleeding, that's fine, I'l be happy to believe it.


talbir

 

“(1) where is the air released from if it is self-bleeding ?”
That, I don't know, but I know that it does based on many peoples experience/training.”

”(2) Why is there a bleeder valve if it is self-bleeding ? “
The bleeder valve is for draining fluid, it says as much in the first PDF.”

During my brief thoughts as to how the air escapes I put some of it to the noise I could hear from the struts and to the return side of the system in the reservoir. I've never given in Terribly much thought until this thread came up as everything functioned/worked with excellent results with the info I had been given.

The fellows I have chatted with are some of the most accomplished Mercedes Mechanics I know. They are kind enough to lend me their time every now and again (an expensive commodity when they charge upwards of 125$/hour) so when they provide me with an answer I say thank you and move on.


”(2) How many of the other fluid systems on the MB cars have a bleeder valve ???

Bleeder valves are there to release air as well as depressurise.


Furthermore, your description of flushing the system isn't right. Bouncing the rear of the car up and down does NOT release the fluid out of the struts. The strut carries a good 5-6 inches of fluid - when you bounce the car up/down at the rear, you will be luck y to get more than 1 inch of travel either way. The only way to drain the struts is either to remove them and drain them by compressing fully, or remove the union connection at the accumulator, then let the car drop at the rear as far as it will go. With no strut supporting the spring, the car will sit down quite low at the back.”

I can't get it all via the above, that I know, but again..someone isn't going to pay for the extra labour to drop their struts just to flush the system..I do the best that is possible w/o going to extraordinary means and cost. The colour of the fluid or changes minimally w/ a few thousand miles after flushing via my method. When lowering a car they system will receive a full drain and flush by dipping the head of the drained strut into a container of hyd fluid and I will expand and contract the strut in and out of the strut a few times thus flushing any remnants.


”Just because MB literature does not talk about bleeding the system, it does not mean it is not neccesary. MB literature also does not talk about renewing the timing chain at 100k miles....so does that mean it's not neccesary ???”

No, but they do so in Many TSB's. And any Mercedes mechanic will tell you that it needs to be done. Just like all the mechanics I know will tell me the system is self bleeding.


”MB literature only tells you what is safety critical - i.e. you need to remove the air from the braking system as it won't function properly without it. It's a safety issue. Same for the steering. But the rear SLS system is not safety critical and the air won't have a massive impact on the system. But if you are not bleeding the air after maintenance, the job's not complete as the system won't be funtioning as well as it should.”

I'll gladly go and pop the bleeder valve on all 4 of the SEC's I have and the 1 wagon. I've done all of those systems and I'd wager quite heavily there is no air in the system.

”To be consistent with your line on MB literature and MB guidelines , why are you using non MB fluid in the system. MB clearly states that only MB fluid should be used in the system ?”

Why, because all MB is using is petroleum based hydraulic fluid w/ some anti frothing/anti corrosion additives. I have a good friend who is a chemist @ a university up north. I sent him a sample of each, the JD fluid came back w/ a bit stronger/more aggressive additive package but that was it. Since I can buy JD fluid by the 5 gallon pail for about 40 $ and the febi fluid is 9 or so per quart I use the JD fluid..it also enables me to flush a system w/o spending a fortune.

Jonathan