ABC issues

[alexanderfoti]

15250 -0 - Critical Vehicle level
15254 - Critical Vehicle level rear left
1526- 0 Fault in hydraulic circuit
1526 18 (have no 18, have 16) - 1526 16 - Malfunction in pressure supply.

I agree with Malcolm. If only one section of the car is raising I think the pressure showing is a red herring. Its possible a control valve is jamming either bleeding of the pressure, or giving an incorrect reading.

 

[Craiglxviii]

Thanks Alex, as I suspected. Gunked up valves. I'll do a flush next week then see. Might need the valves stripping and rebuilding.

 

[alexanderfoti]

Thanks Alex, as I suspected. Gunked up valves. I'll do a flush next week then see. Might need the valves stripping and rebuilding.

I have had success in many cases just doing a Rodeo, then a flush

 

[Craiglxviii]

Thanks Alex. Sorry I've not been back in touch since last week, busy weekend for one reason or another!

So to cut a long story short............

Friday morning saw the car drop down on the right rear corner, to the point of rubbing a groove in the rubber where it was rubbing against the wheel well. I pulled over and much turning on and off of the engine along with ride height level adjust (when I say much, I mean ~25 mins!) saw the "STOP! RIDE HEIGHT TOO LOW!" warning merely be replaced with the "ABC DRIVE CAREFULLY" one. So I was able to get home. Some points that I observed:

1. At this point system pressure was 175bar.
2. While standing outside the car with the engine just having been shut off, hood open, looking to see if any fluid had been burped out of the header tank, I heard a high pitched, quiet whining/ hissing sound that sounded like it was coming from the pump.
3. On driving home (no wheels rubbing) the ride height level sensors reported:
F-L: -84mm
F-R: +20mm
R-L: +20mm
R-R: +20mm

4. After getting home and doing various other things, I noticed a small puddle of fluid just inboard of and behind the front left wheel.
5. New Pentosin fluid should be greenish, the fluid from the dipstick already looks mucky.

I have bought 12 litres of Pentosin which is winging its way to me and should be here later this week. My plan is to do a flush and see what happens. If that doesn't solve it I'll risk driving it to Mercland in Nuneaton (closest place I can think of that has been endorsed here) to see what they can do.

 

[alexanderfoti]

Those level sensor values, where they accurate? was the car ok apart from the Front Left wheel?

 

[Craiglxviii]

They were what the iCarsoft i980 was reading, live, while I was driving home. As to being accurate I couldn't say. Certainly the wheel that was rubbing was the right rear not left front. However I've noticed that the left front has sagged as of this morning.

 

[Craiglxviii]

Malcolm suggested that the temperature (?) sensor washer may have gone, resulting in the fluid leak at front. I think that this is a 12mm ID x 1mm thk copper washer as replacement, so no problem sourcing that. I may as well do the rear at the same time, can anyone tell me how hard the rear valve block is to access on the 215 please?

 

[alexanderfoti]

They were what the iCarsoft i980 was reading, live, while I was driving home. As to being accurate I couldn't say. Certainly the wheel that was rubbing was the right rear not left front. However I've noticed that the left front has sagged as of this morning.

Im trying to think if that's the vehicle level or the wheel level.

If vehicle level, then it would be low all round, and that reading would tell me you have an intermittent faulty sensor on one wheel.

If you have a leak then you do need to track that down. Possibly a pin hole leak in the hose or from the strut itself.

The front/rear valve body is easy to locate for leaks. The pressure sensor is on the front right, so possibly not that leaking.

The front one is accessible from the front left wheel arch. Or from underneath the front bumper covers.

The rear one is easy to get to, just jack the back left of the car up, and remove the cover with 10mm plastic nuts. It covers the fuel filter assembly and the valve block.

Have a look at my guide here:

http://fotifixes.com/2015/01/18/how-to-change-abc-accumulators-on-a-mercedes-cl-215/

 

[Craiglxviii]

Those levels were given for each corner not the car as a whole. There are a fair few values available to choose from in that reader...

 

[alexanderfoti]

Those levels were given for each corner not the car as a whole. There are a fair few values available to choose from in that reader...

The 2 main ones are vehicle level and plunger travel sensors.

Yes sorry, I Was using the star terminology (vehicle level) rather than referring to the vehicle as a whole.

20mm is the vehicle fully raised, I think (2 lights). Did you have it raised up at that stage?

 

[Craiglxviii]

Oh yes. I had the thing jacked up as high as it would go, I have a rather unpleasant groove in the outside shoulder of my right rear tyre from the wheel well rubbing into it, didn't want to risk that happening again while driving home- I had visions of the tyre sidewall bursting and didn't want to lose a wheel for the second time on the same car!!!

Vehicle level values. Plunger travel was a different option that I didn't look at, although available I seem to recall.

 

[alexanderfoti]

Oh yes. I had the thing jacked up as high as it would go, I have a rather unpleasant groove in the outside shoulder of my right rear tyre from the wheel well rubbing into it, didn't want to risk that happening again while driving home- I had visions of the tyre sidewall bursting and didn't want to lose a wheel for the second time on the same car!!!

Vehicle level values. Plunger travel was a different option that I didn't look at, although available I seem to recall.

I can imagine.

OK, so either there is a broken level sensor or there is a fault with the valve body.

I would take the FL wheel off and check all the hoses, connections around the strut and the valve body, as its that wheel that's dropping as well as the location for the leak.

 

[television]

The washer on the sensor in the valve block are known to leak, just fit a copper one, I have had 2 fail.

Re the level sensors, a good call by Alex One big trouble that I had was that the connection to the ABC ECU was poor, non drying switch cleaner fixed my long ongoing fault.

Re measuring the height all round, the ground must be dead level, A slight hump on one corner will affect the opposite corner.

 

[alexanderfoti]

Re measuring the height all round, the ground must be dead level, A slight hump on one corner will affect the opposite corner.

Its a real pain getting them level!

 

[television]

Its a real pain getting them level!

I think that I have it off to an art now, auto level struts and sensors more than once, then set height and store by entering Load menu. If anything is way out the Load menu will send it all over the place. On the 230 one can just get to the USA height settings, but much easier to set to the UK height.

 

[Craiglxviii]

I have a fairly level-ish driveway but it's not billiard-table-like. In fact I don't know anywhere that has a dead level & flat surface to work on.

I also don't have STAR so I can't reset any values by myself..........

 

[Craiglxviii]

I can imagine.

OK, so either there is a broken level sensor or there is a fault with the valve body.

I would take the FL wheel off and check all the hoses, connections around the strut and the valve body, as its that wheel that's dropping as well as the location for the leak.

OK, I can see my Saturday morning is going to be busy then!

 

[Craiglxviii]

Any further thoughts on the whining/ hissing sound coming from the pump area after the engine has been turned off?

Remember- new pump has been on the car for 3 weeks...

 

[alexanderfoti]

Any further thoughts on the whining/ hissing sound coming from the pump area after the engine has been turned off?

Remember- new pump has been on the car for 3 weeks...

I would not worry about it too much, I have heard lots of pumps make this noise with no consequence. It could indicate that your pressure accumulators are on the way out and are returning the fluid they have taken on back to the system.

 

[Craiglxviii]

Maybe, although I've only heard that noise starting from Friday and at no time at all beforehand... I have an irrational fear of the pump running in a vacuum and auto-disassembling at high velocity