Odd ABC problem
 

Hi all

First off, Merry Christmas and happy new year!

I am quite an active member on the UK forum mercedes club, as some of the cars over here are less common in the UK and vice versa. I am having some issues with my ABC system which is far less common in the UK than in the US, hence my post on here.

I have had 20+ mercs and keep my own STAR diag system etc, so am pretty in tune with them, but this has me and my indy stumped.

I have a 2003 CL55 AMG on 91,000 miles. I have had it for the last 5 months or so, and have put 4000 miles on it. It has recently started to have issues with ride quality. The suspension intermittently goes from being soft, to bone shakingly hard and back again.

It doesnt seem to be in relation to anything, and as our roads are very badly potholed its very easy to feel when its gone hard. Even the other half noticed it (it must be bad then!)

Its especially bad on the rear but the front goes hard too. Its the most noticable on cracks in the road that go all the way across, when its soft you dont feel them. When its hard it shakes the whole car when you hit them.

Speed bumps and rolling dips are still soft in the car, its just the cracks/potholes that jar the whole vehicle.

The ABC pump passes a rodeo test with flying colours, as well as a dynamic test and there are no faults showing on the car. I recently replaced the front pulsation damper as it had failed, but no change.

The Accelerometers pass the STAR test for roll and acceleration/braking on all 3 corners.

The rear left level sensor was very stiff and was reporting a value outside of the specified voltage range in star (2.00v to 3.00v). It was reporting 1.8v or so. I replaced this sensor but the values it reports are still the same. The vehicle ride height on the rear left are shown about 8mm lower than the rear right, but the car is sitting level. So I havent put too much on this one being incorrect.

Im completly stuck on where to turn so any advice would be very much appreciated!

accumulators.

Even with no ABC errors/faults?

The accumulators are nitrogen filled and will lose pressure over the years. If the accumulators are over 8 years old (or have over 75,000) miles on them I would go ahead and just replace them as a general maintenance item. You could check each for a rupture diaphragm first, but that is only part of the issue with these units. Loss of pressure which you can't check also effects the ride, etc.

Fair enough, they are about £380 which is pretty cheap for ABC maintenance so I will replace and report back.

accumulators don't throw a code.

Sorry for the delay in coming back to you guys.

All replaced today. Front and rear Accumulators and the return one done as well. Went for a long test drive on all different types of roads.

It does seem better, I would say 30/40% better. I think the old spheres where worn. On the plus side it does seem as though my rear valve block has been replaced with the newer/updated one at some point (so replaced in/around/after 2007/08?).

I think the remaining issues with ride quality are down to my choice of wheel. 19inch AMG Style IV are a fair bit heavier than than the style III that they replaced. Unsuprung weight has the worst effect on ride and handling I belive.

All in I feel happier that they have been replaced and may now turn my attention to the suspension/bushes.

Have a look at the front strut rubber bushes where the strut passes through the aperture. Is there a small gap between the small bush and the metal? If you jack the car up, does that gap close up? Its a common issue with the W215/220.

Nick

Many thanks, is the problem you are talking about illustrated in this post?

https://mbworld.org/forums/s-class-w...ml#post6275116

Just went and checked by jacking the car up. Yes I have lots of play in those top mounts. I have bought some 10mm rubber sheet and a 35mm pin spanner as your post and will work to get that sorted.

Does the 10mm rubber bush go on the engine bay side or on the underside?

On mine the rear is worse than the front. You say that the same procedure cannot be done on the rears, also access seems to be done via the parcel shelf at the back which seems a pain.

Is there a way to check if this same play is present on the rear suspension too?

Many thanks!

If you put the bush on the underside, it would bear the weight of the car, so I would leave that to the main bush, and put the new bush on the top side, under the existing bush.

I had a similar problem with my rear strut bushes, but couldn't find any way to fix them. I had to replace the whole struts. Not too difficult. Access via the parcel shelf. Ping me if you want help. There's a few techniques...

Its really worth fixing the bushes.

Nick

Thanks for your advice Nick, much appreciated.

I have a 35mm pin spanner and 10mm rubber sheet on order. I will get to work making those replacement bushes but replacing them on the front seems pretty easy.

I will put them between the existing bush and the top.

Its a shame about the rears, I will check to see if I can feel the same type of play on the back wheels. I will probably go down the refurbished shock route, although im not 100% sure as I have heard mixed reviews about arnott etc.

New from Mercedes they are £1150.

Used struts in good condition are easy to find on ebay for a reasonable price. Garages buy new and charge the earth. There are plenty of cars being dismantled now, and few people who will do this themselves, so supply is high and demand is low.

You can expect to find struts with no leaks, no rust and good bushes top and bottom for under £200. The plastic boots that cover the springs are normally split; don't worry about that.

Although I didn't need to change mine to through the MoT, I changed them anyway, and was really glad I did. It rode and handled properly again. Judging by your blog, this should all be right up your street.

Nick

Its good to know theres lots of good struts on ebay.

Ill try and find some there. I Was worried that most of the ones I would find are from high mileage cars, which are likely to have the same worn bushes as mine. I suppose I could find a supplier that provides a warranty.

I know the fronts are easy to check, are the top bushes on the rears easy to check when they are off the car?

Thanks, Ill normally give anything a go once. Might as well document it in case it helps somebody else!

Checking the front strut bushes is easy - you just open the bonnet and look at them.

For the rear bushes, you need to jack the car, and bounce the wheel up and down, hard.

It shouldn't move if the bush is good. If the bush is bad, the wheel will move up and down freely for a few mm. Thats what it will do over broken surfaces at speed. Its quite shocking.

Nick

I meant when they are not installed.

As in if I buy some second hand rear struts for my 215, can I check the condition of the top mounts before I fit them to the car?

Accumolaters
 

Anyone have a source, part #, cost, and how many accumulators?

I wrote a guide when I changed mine with the part numbers and location/number:

http://fotifixes.com/2015/01/18/how-...rcedes-cl-215/

In the UK I could only get them from main dealer. They cost me around £400 or so.

Sorry about that, I should read twice and typed once.

The rear bushes are bonded to the top of the struts, and the mounting plate with three studs is bonded to the top of the bush.

The problem is that the bush becomes disbonded from the top of the strut, and you can feel the bush wobble when you handle it.

Also make sure the ball joints at the bottom aren't seized, loose or dry. While the strut is out, try to get some grease in there; they squeak eventually.

Nick

Not to worry, I do it most of the time too.

Excelent thanks, I will keep an eye out for some replacements and will investigate the ones on my car at the moment.

You could try CNOCARS?

http://www.cnocars.com/pshow.asp?id=618

Hmm interesting, any reports of anybody else using these with any degree of successs?

Just fitted my upper bushes as per your other post Nick! The fronts are very much improved, the rears are the same, but not that bad all in. I suspect that I am just going to put up with the rears until I find a cheap replacement.

Saying that I havent tested the rears for play but will assume there is some!

I did a guide for the front bushes, thanks for your help!

http://fotifixes.com/2015/01/24/how-...rubber-mounts/

Nice work Alexander, that's just how I would have written it.

I noticed that you left the shallow rubber bush on the strut top nut/washer. I cut mine off, so that the only bush was the new one.

What happened then was that the single 10mm bush was still too shallow for the strut top, and I still had a small clearance when the weight was on the wheels.

Although the ride was greatly improved with the thick bush, I think I really needed 12-15mm instead of 10mm on my car. I suppose it varies from car to car, depending on how much the strut bushes have settled over the years and miles. However, it looks like the 5mm + 10mm bushes on your car looks just right, and in hindsight I wish I'd done the same on mine.

I think the recommendation is that you need a total of 15mm rubber bushing for the top mount, but it will depend on the individual car. All the cars I've seen needed some sort of bush work here - I think its a typical problem, rather than isolated instances.

Therefore anyone with an old or high mileage W215/W220 with ABC should do this fix.

Nick