todd_raleigh

I replaced my accumulators this past weekend and attempted to replace the hydraulic fluid. I used these steps (using the WIS document):

1) Put rear of wagon on jack stands (not stated specifically in WIS, but I wouldn't be able to get the accumulators off any other way).
2) Removed rear tires
3) Detached the link rod on the level control lever
4) drained the fluid out via the level controller oil drain screw (about 1 liter drained) and closed the oil drain screw
5) removed passenger side accumulator and installed new accumulator
6) removed driver's side accumulator and installed new accumulator
7) syphoned hydraulic fluid out of reservoir and filled with new fluid to max line
8) set level controller lever to "F" position
9) started engine. Ran it for 60 seconds at 2500rpm. Turned engine off. During that time, the fluid reservoir dropped some and I added to it to bring it to the max line.

Question: about 20-30 seconds into the engine running, a whining noise came from the rear end and got progressively louder for the remaining 60 seconds. Is this normal?

10) set the level controller lever to "L" position.

Question: Once I moved the controller level to the "L" position, it sounded like fluid was draining or moving between systems. I checked the reservoir and it was overflowing. Either the fluid was backing up into the reservoir or returning back to the reservoir via it's return line. The amount of fluid that overflowed was about the same amount I put in in step #9. Maybe more. Can't say for sure. Is the draining noise normal? Is the fluid backup to the reservoir normal?

11) Well after the 60 seconds required in the "L" position, I secured the link rod on the level control lever. I noticed that the position of the lever stayed basically in the "L" position.
12) Put the wheels back on and took the car off the jack stands.
13) Opened the wagon hatch and bounced up and down on the rear end about 10 times.
14) Measured the height of the rear on both sides. 27 3/8" on drivers side and 27 5/8" on passenger side. Height measured from ground to top of wheel well.
15) Started car and drove it several miles. No whining noise.

This is the correct procedures described in WIS, but should I have experienced the issues that occurred in steps #9 and #10?

Do you think anything is damaged?

thanks!!!

thanks!

Plutoe

Did you also use WIS doc AR3230P0630P and AR3230P0520A????

todd_raleigh

Hi Plutoe, thanks for the reply.

I started with ar32.30-p-0620a (Rear hydraulic suspension pressure accumulator, removal and installation). The first step said to drain the system, which references ar32.30-p-0630a (Emptying and filling pressurized oil system). I emptied the system using steps 1-4. I just noticed that 0620a doesn't say anything about filling the system back up after installing the accumulators, but I filled it up anyway (using ar32.30-p-0630a steps 5-11) after replacing the accumulators.

I did not use ar32.30-p-0520a which you state. I'm looking at it right now. It seems that I can use this procedure to see if everything is in good working condition. I notice that for this test, the vehicle weight must be on its wheels and that when the lever is in the "F" (filling) position, it will emit a whistling noise as it opens. That appears to be good news since that must be the sound I heard in step 9 in my OP. Do you agree?

I'm still puzzled about what happened in step #10. I wonder if I should not have added fluid to the reservoir in step #9. WIS said to monitor the fluid level. It did not say to add any if it goes down. But, it didn't say not to add any either. If I were to do it all over again, I would not have added any fluid in step #9.

todd_raleigh

I think this is starting to make sense. I have some thoughts on steps 9 and 10. Tell me if they make sense.

In step #9, moving the lever to the "F" (fill) position causes the fluid to fill the accumulators and hydropneumatic spring legs which raises the rear end. This also results in lowering the reservoir fluid level. Moving it back to the "L" (empty) position causes the fluid to drain the accumulators and hydropneumatic spring legs which lowers the rear end. This also results in raising the reservoir fluid level.

However, the first step in replacing the accumulators is to drain the system via the suspension control module. I drained about 1 liter of fluid. This did not lower the reservoir fluid level. Why?

I am thinking that the 1 liter of fluid that came out during the draining process was fluid in the accumulators because the accumulators were shot.

Plutoe

Makes sense to me. The worst case is that you can drain and refill until you think you have it correct!!

todd_raleigh

Plutoe, do you have any thoughts on why draining the system didn't take anything out of the reservoir?

Plutoe

Based upon what I have read, the key word is depressurize not empty, that being the instruction verb age I would not expect to empty the system of fluid. simply drain enough fluid to reduce the pressure so I could work on the system.

The depressurizing and filling is a simple process---why not just re due the process to help satisfy yourself!!

Hml3415

Todd really great description of how you changed out your accumulators. I am trying to do the same but have some questions if you could respond to them.

1. can this be done with the car on the lift, with the tires simply hanging without any weight on them?

2. It looks like I can access all the parts of the accumulators and remove them from below on the lift. Do you agree?

3. Once the accumulators have been replaced is it necessary for you to move the lever to fill and level as you did or will the the car do this automatically when I start driving it?

Thanks very much!

Howard

todd_raleigh

Hi Howard,


Answers to above.


1. My wheels were off the ground using jack stands. You can do the same with a lift.


2. I don't know if you can get access to the accumulators without taking the tires off, though.


3. The car does not do it automatically. Once the new accumulators are on, you will need to fill the suspension system with new hydraulic fluid as described in steps 7 thru 9. By the way, the reservoir I talk about in step 7 is the reservoir in the engine compartment.


With respect to step 9, it is a two person job. Have some new fluid ready to add to the reservoir. You may not need it, but if you do, you need to be prepared. During step 9, DO NOT add fluid to the reservoir unless the level drops to the point where it will become empty. You DO NOT want the system sucking in air! During step 9, the fluid level in the reservoir will drop super fast which is normal. Only be concerned if the reservoir level gets low to the point where it will be empty. If that happens, I would start adding just enough to make sure it doesn't go empty. The fluid transfers from the reservoir to the suspension system. I believe this raises the rear of the wagon. The whining as described in step 9 is normal.


In step 10, when moving the lever to "L", the fluid moves from the rear suspension system back to the reservoir because you are now leveling the rear suspension. That is why the reservoir is so large, it need to accommodate the transfer of fluid to/from the rear suspension.


After step 14, check the fill level of the reservoir and add if needed.


I hope that helps.

RichardM98

Because the power steering pump didn't run. The system is recirculating. When you start the car, the pump will start and the level should drop accordingly.

Hml3415

Todd, thank you very much for your quick response!!

From your response I understand that:

I can do this from a lift
I will probably need to take the tires off although when I look at it it appeared that I could do this without removing the tires

Question: how do I relieve the pressure in the system when I start to remove the accumulators, do I use the bleed valve located on the leveling valve?

Question: Once I remove both accumulators and replace them, how do I actually start moving the lever from level to fill? Do I need to disassemble the linkage?

I understand the filling is a two person job to one person to fiddle with the fill and level lever and the other to fill the reservoir.

Question: you didn't mention anything about bleeding the system and I read somewhere where it self bleeds is this true?

Thanks very much again for your help?

Howard

Hml3415

Hi Todd,

A follow up question from several months ago. I had the E320 wagon up on a lift but was stymied when I could not figure out how to disconnect the fill lever...Can you explain how the lever can be temporarily disconnected so that it can be manually moved from L to F, etc...

Thanks in advance!

Howard

todd_raleigh

Hi Howard,

Sorry, but I didn't see your post from January until just now.

I think the information in these links will help you out:
http://www.benzworld.org/forums/w210...hydraulic.html

I have detailed instructions on what I did on this post (with WIS documents):

http://www.benzworld.org/forums/w210...ml#post6632154

I hope this helps. If not, post additional questions.

best,

Todd