R230 - ABC Fluid level while engine running

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Koopz

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Just checked the levels again, engine off still exactly where it was right on the high mark. Start the engine, drops to the very bottom of the dipstick. So it really doesn't seem like a leak but the fluid must be going somewhere
 

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Are you sure you're looking at the correct side of the dipstick? Engine off is labelled AUS, engine on is AN.
 
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Are you sure you're looking at the correct side of the dipstick? Engine off is labelled AUS, engine on is AN.
Yes. Engine off its at the AUS mark, engine on its about an inch up the dipstip at best, miles away from any marks
 
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So I took the car out this morning for a 10 minute drive to the shop and back, checked fluid level with engine off first - at the correct level. After about 2 mins driving I got the white ABC fault, couple more minutes the red one. Carried on to the shop, on the drive home I got the white ABC error, no red one this time. Checked the fluid with the engine on and it was right at the bottom of the dipstick, but I noticed there were bubbles on it. Checked again a couple more times and the level was actually rising up closer to the lower mark, still lots of bubbles. Just went out and checked after letting it sit for half hour with the engine off, and it's about a cm below the top "engine off" mark - so unless that's been caused by me sticking the dipstick in and out it's lost some fluid. I'm going to top it up to the correct mark again and keep an eye on the level
 

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Sounds like you may have air 8n the system somewhere (which would also account for the levels).
 
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Is there a good method for getting air out of the system? This also might tie in with a failed accumulator if it is releasing gas into the system? I've ordered 2 accumulators and a pulsation damper seen as it seems a good idea to replace them at this point regardless, and it looks like something I should be able to do on the drive.
 

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Normally a Rodeo test is used to get air out though in some cases it may be necessary to manually bleed at each bleed point by the struts.

I'll say it again though, you aren't showing any of the symptoms for a failed accumulator.
 
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Just went out to top the fluid up, over-filled it slightly just to get it above the top engine off mark. Started her up and cycled through the hights about 10 times - nice and smooth, went up and down fast, no weird noises, no errors. Checked the fluid with engine on, still very very low. New parts should be coming this time next week so I'll get those fitted if the weather holds up and go from there
 
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Well just an update to this, checked the fluid again today and it's slowly going down. Had a look under the car and there's fluid on the floor under the front left wheel arch so I've got a leak. Also because the car has been sitting it seems I've now got battery issues as well o_O

Once the new accumulators arrive this week I'll get the car up and have a proper look to see where it's coming from
 
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Thought I'd post an update for anyone else having similar issues.

Decided to do the front first and see how it goes, so I ordered an accumulator and pulsation damper direct from Mercedes. It was the same price as what I could find elsewhere so made sense to go direct. Also ordered a new front wheel arch liner and undertray and they were actually cheaper from Mercedes than elsewhere - just shows it's always worth asking for a price from Merc first! Over the weekend I swapped them out - actually a pretty simple job. The accumulator was easy to get to with the front wheel arch liner and front bumper tray removed, and the pulsation damper is even easier. If you remove the side "vent" cover, it's right there. I didn't even need access from behind the wheel. It was on very tight so I soaked it in WD40 overnight and the next day it came off just fine.
Put everything back together, topped up the ABC fluid and took her out for a 30 mile drive, good mix of motorways and back roads, lots of bumps. No errors! So it definitely looks like the accumulators were the issue. The fluid in the reservoir is still low when the engine is running, but not as low as before - I'm guessing once I get the rears changed as well it will be back to normal.
So next job is to change the rear accumulators, and then I need to sort out the leaky boot!
 

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Thought I'd post an update for anyone else having similar issues.

Decided to do the front first and see how it goes, so I ordered an accumulator and pulsation damper direct from Mercedes. It was the same price as what I could find elsewhere so made sense to go direct. Also ordered a new front wheel arch liner and undertray and they were actually cheaper from Mercedes than elsewhere - just shows it's always worth asking for a price from Merc first! Over the weekend I swapped them out - actually a pretty simple job. The accumulator was easy to get to with the front wheel arch liner and front bumper tray removed, and the pulsation damper is even easier. If you remove the side "vent" cover, it's right there. I didn't even need access from behind the wheel. It was on very tight so I soaked it in WD40 overnight and the next day it came off just fine.
Put everything back together, topped up the ABC fluid and took her out for a 30 mile drive, good mix of motorways and back roads, lots of bumps. No errors! So it definitely looks like the accumulators were the issue. The fluid in the reservoir is still low when the engine is running, but not as low as before - I'm guessing once I get the rears changed as well it will be back to normal.
So next job is to change the rear accumulators, and then I need to sort out the leaky boot!

Thanks for the update, really great that you have sorted that issue. Hope you sort the leaky boot.
I have the same issue with water getting into the boot which appears to be coming over the rubber seal at both areas where the rubber and boot lid touch, I can see a flat spot on the rubber seal and I think I will need a new seal to sort this. Look forward to your update on the leaky boot koopz :)
 

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Look in the archives for water leaks into the boot. It’s always more of a job than just changing the seal C70F62B3-C918-4EB9-B6D6-2E0981A54C10.jpeg 7ADCCB55-6E43-4D19-A92C-48FE0C9D049D.jpeg
 

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Hi I'm resurrecting this thread as it is very helpful, rather than raise a new one.

No leaks, no ABC warnings but I do seem to feel pot holes more recently. I've been checking my ABC fluid level, it was low, currently I have it at the bottom 'max level when running' which is fine but when I switch off and wait it goes way above the higher 'max level when off'. So basically the same problem as the OP except that I overfilled to avoid ever going below the lower max level.

So the system is swallowing up more fluid when running than it is meant to. I assume this is a sign of one or more failed accumulators. I can't get my head round why though - if an accumulator fails then eventually the nitrogen will get bled out resulting in increased fluid capacity in the system, but when switched off there will be less or no compressed nitrogen to push the fluid back. So I would expect the on-off range to be narrower with a failed accumulator, not wider???

Koopz, did replacing the accumulators bring your level range back to normal? Or anyone with a normal ABC system - is your fluid range 'max level when on' to 'max level when off'? If so can anyone explain why a failed accumulator increases the range (if indeed it does)?

 

dldb

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After quite a lot or internet searching (including some wrong info) I think I have found the answer. I think the range of ABC fluid should be exactly as on the dipstick - at the lower 'engine on' mark when idling and at the higher 'off' mark when the engine has been switched off for at least 10 minutes. If the range is greater than this then at least one accumulator diaphragm has split and fluid is entering the nitrogen void behind the diaphragm when the pump is running (so the level drops below the 'on' mark) and leaving it under now unrestrained pressure from the nitrogen when the pump is off, possibly overflowing the tank. As more nitrogen is lost the range increases. As people top up the level when on, the off level rises above the 'off' mark. If you don't top up to the 'off' mark then, when on, the level goes below the 'on' mark. That I think is more dangerous to the system than not topping up to the 'off' mark. But really it needs a new set of accumulators.

I am guessing that, apart from the levels range change, the only sympton, assuming you keep the levels up, is a harsher ride. There could be rubber debris floating around, hopefully the filter will catch it.
 

ajlsl600

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Removing one by one the failed one will be very easy to spot. However at that age and with no further info. Replace all. Incl fluid and filter. Before u do check pressures are in specc. No point in changing above with pump on way out.
 

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i
After quite a lot or internet searching (including some wrong info) I think I have found the answer. I think the range of ABC fluid should be exactly as on the dipstick - at the lower 'engine on' mark when idling and at the higher 'off' mark when the engine has been switched off for at least 10 minutes. If the range is greater than this then at least one accumulator diaphragm has split and fluid is entering the nitrogen void behind the diaphragm when the pump is running (so the level drops below the 'on' mark) and leaving it under now unrestrained pressure from the nitrogen when the pump is off, possibly overflowing the tank. As more nitrogen is lost the range increases. As people top up the level when on, the off level rises above the 'off' mark. If you don't top up to the 'off' mark then, when on, the level goes below the 'on' mark. That I think is more dangerous to the system than not topping up to the 'off' mark. But really it needs a new set of accumulators.

I am guessing that, apart from the levels range change, the only sympton, assuming you keep the levels up, is a harsher ride. There could be rubber debris floating around, hopefully the filter will catch it.
My understanding of the system is, that oil only gets filtered in rtn line ie after all crxp has travelled thru system!!!
A pressured filter in feed line wud be "proper" but more expensive at build
I have seen a utube on a guy fitting filter in press line.
Abc is brilliant, when working correctly and an expensive pain when not
I wud hav considered coil overs but they are not, or were not avail for v12.
 

dldb

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Yes the filter is odd. Normally with a cylindrical filter the fluid will pass from the outside to the inside of the cylinder, because the surface area on the outside is more than the inside. Mercedes seem to do it the other way round on this particular filter. I guess the rubber particles will get caught in it eventually.
 

ajlsl600

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Yes the filter is odd. Normally with a cylindrical filter the fluid will pass from the outside to the inside of the cylinder, because the surface area on the outside is more than the inside. Mercedes seem to do it the other way round on this particular filter. I guess the rubber particles will get caught in it eventually.
Full fills requirement, gets it past warranty. Not quality tho.. That's now just an illusion, even mielle stuff is full of prc crxp.
 

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