S-Class (W221) 2007-2013: S 320 CDI, S 350, S 450, S 500, S 550, S 420 CDI, S 600

S600 rear ABC accumulator replacement

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Old Sep 21, 2022 | 05:55 PM
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kn51's Avatar
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2007 S600
S600 rear ABC accumulator replacement

Not a lot out there, and what is out there on replacing it is sort of spread across various threads and places that leaves some questions unanswered. So, after doing it I thought I'd throw it here on what it takes.

First of all, shortly after having work done on the front ABC valve body, the car would start with a "growl" noise for about a second then go away. Only to reappear on the next start. Since the front has been replaced, I figured I'd take a chance and replace the back one since it is probably original to the car. With a properly functioning valve body the system found the rear accumulator as the weakest link was my theory.

If you read the WIS, it will say you need to drop the exhaust. You do not. It will be somewhat tight because you will be futzing around the heat shield and might be even more difficult if you have hulk like hands. What you will need or at least makes the job a lot easier is a wobble extension to work around the heat shield.

1) The car sat overnight. I supported just the rear of the vehicle while chocking the fronts.

2) The accumulator sits next to the spare tire. One of those things that you've seen yet forget about.

3) Drop the rear spare tire pan. This is fairly straightforward. I think it was a T-15 for the screws and a 8mm wrench for the two side bolts. As I was unbolting it I was thinking "how the heck will I get this back in place" type thoughts but getting it back on is simple. The screws are going into plastic and lining it back up on the reinstall is easy.

4) Clean the area underneath. Undo the 3 10mm nuts underneath to the accumulator. This is where the wobble extension comes into play. They and the threads appeared rusty but came off fairly easy. Next up, undo the line which is a T-50.

5) Now, here comes the not so fun part. I tried pulling the line off and it wouldn't budge. The exposed part of the accumulator was quite rusty. So I went above and started manhandling the accumulator just a tad. I was able to pull it up enough to clear the mounting holes and gave it some twisting motions. Eventually it popped free, which will be a surprise when going this route, so have some old towels/rags/whatever around that general area. Not much spilled out of the accumulator, maybe a couple teaspoons. It did require a fair amount of effort to separate it.

6) The now open line did not spill a drip.

7) I used a Corteco accumulator. It felt like they pre-lubricated the orifice so I dropped it in paying attention to how the line fitting lined up.

8) Tighten the 3 nuts but not all the way. Don't try starting them with the wobble extension otherwise you can cross thread them. Use your hands.

9) Then attach the ABC line. For me, this went on fairly easily however I've read another account where they struggled with it. Now the part that was the absolute most maddening for me was getting the bolt started for the fitting. It has to be dead straight to catch the threads. Leaving the other 3 nuts a little loose allowed some play to get it lined up.

10) Tighten everything, replace the pan and that's about it. Starting the car instantly solved the growl noise and I didn't bother doing a rodeo. Rides nicer, at least according to my rear end.


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Old Nov 10, 2022 | 01:27 PM
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2009 S550, 2016 Kia Soul EV, 1973 Avanti II
Thanks for this. I've been doing some research on this lately and have found very little. From looking at the WIS, it seemed that the accumulator was above the trunk floor, but apparently not.
I was thinking of replacing both accumulators just for preventative maintenance. I replaced the pulsation damper a couple years ago and hope I never have to do that again!
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