I had (have?) a strange ABC issue that is never happened to me before.

When I started my 00 S500 this morning to go the shop I noticed that the steering wheel "wants" to turn left on the even road and also I found that the new centre position is 30~40° CCW to the original. I thought I got a puncture on the FL wheel. After stopping I realized that all wheels were OK but the FL corner was a little bit lower than the others. When I started to go home, the white "Visit ABC Workshop" message was displayed and the steering wheel was also abnormal.

At home I tried to lift up & down the car but there was nothing. After turn-off then turn-on the car, the red ABC warning message was displayed, the FL corner was noticeably lower then the other. I checked the oil level and condition, the level and the color were OK. I checked the bottom of the car and I found a little amount of the ABC oil on the left control arm, but the strut itself was absolutely dry.

After some hours I decided to change the cars on the yard, so when I turned on the S500, there was only white ABC message! To bring forward my old 96 LHS, I stopped the S500, when I started again there was no any ABC message, the FL height and the lifting up & down were OK!
Then I measured all corners (bottom of the wheel to the fender measured at the centre of the wheel):

Front left - 69,5cm
Rear left - 66,5 cm
Front right - 67,5 cm
Rear right - 68,0 cm

The measuring was done on uneven and grassy yard so it's quite good.

It possible that the ABC system was overfilled with oil then due to certain conditions the excess oil was escaped thru a pressure-valve resulted in temporary malfunction?

Any helps are appreciated!

Regards,
Csaba

Update:

I found traces of oil on covering of the front bumper the lifting still works.

 

Check the oil level in the ABS reservoir with the engine running.

Get those covers off and look for the leak.

Nick

 

Thanks for your prompt reply.
I will check the oil level by tomorrow.
Unfortunately I can inspect the possible leaks behind the covers at the very end of the next week due to my working time...

Regards,
Csaba

 

If you have alternate transportation to work, you would probably be better off using that until you've pulled the covers and identified the source of the oil.

 

Yes I have 2 more car, unfortunately the 99 LHS has a bent valve problem (exploded timing belt tensioner bearing) so I have to use my old 96 LHS to go to work ...

At the very first time I would come home in the daytime I will check the source(s) of the leak.

Regards,
Csaba

 

I found the leak.
There is a joint behind the cooler. Looks like the pipe coming from the driver side has the leaking problem.
I hope the local service can fix it...

Regards,
Csaba

 

A hydraulics /forklift company can usually fix hose problems much cheaper than a Mercedes dealer

 

This is not a strange ABC issue, it is typical result from lacking of maintenance.
Check my maintenance thread in signature. Read and you will get sufficient info to maintain the ABC. Start with post 173 to understand ABC.

Briefly speaking, you have wet/leaking pressure hose(s). And your fluid maybe low which cause system malfunction or the front valve body is going. Fortunately, nothing major yet.

Anyway, identify all wet hoses and replace. Then change fluid/filter and cycle the system. If the front issue persists, clean your front valve body.

Thanks.

Howard

 

In fairness, Mercedes (to their discredit) don't specify any routine maintenance for the ABC system, and its only resourceful owners like Howard who are figuring out the best approach to maintenance.

The hoses at the front of the engine fail frequently. So frequently in fact, I'm tempted to say that you shouldn't wait for them start seeping, but pre-empt any failures by replacing all the flexible ABC hoses in the engine compartment every 5-6 years as a matter of routine.

Its the crimped joint between the hose and the fitting that fails. The pressure of the oil simply pulls/pushes the hose out of the fitting over time. Service life of hoses is always difficult to predict, but high ambient temperatures tend to make them fail sooner rather than later.

The most convenient solution is probably to use 10mm compression joints for each and every hose (apart from the pump outlet - 12mm). That way the hose is easy to replace the next time it fails!

The other thing that I'd recommend is to fit every hose in the engine compartment with a foil & fibreglass fire sleeve to help protect it from the high temperatures. Mercedes do use them for some hoses, but I think it should be all hoses. It gets hot down there, and rubber and plastics aren't up to it.

Nick

 

I have updated information on the ABC failure.

Yesterday I went to a local MB Service Centre. During the start up the white ABC message displayed, no lifting up/down and the steering wheel's centre position was changed to ~20-40° CCW as described before.
When I arrived to the service I had to stop the car then after some minutes I started up again, the right side of the car jumped a little (?), no any ABC message, steering wheel position was OK, lifting up/down was OK.

I noticed that if there is white ABC message displayed, the passenger side of the car is lower than the driver side.

The result of the inspection:

• the leak is at the tandem-pump (car was raised up)
• the pump couldn't provide enough pressure
• the front valve block is needed to be cleaned
• there is a sensor problem at the front-right strut (it may caused by the low pressure)

The total repair cost is about 630 USD, including refurbishing the tandem pump, cleaning the front valve block, flushing the system, installation cost, labor cost.

Rodeo test:


Regards,
Csaba Filcsik

 

How did they "refurbish" the pump?

 

That's s good price where did you have it done

 

I'm pleased its fixed for you. My experience is that refurbished pumps dont last long. Pressure is typically lower than spec too soon. So keep an eye on it and hope yours is OK.
I future I will only install a new pump.

 

the fix i believe is a replacement o-ring kit that fixes external leaks on the pump body. It does not overhaul the pump.

 

For about $25 US you can buy a new aftermarket piston ring that will greatly improve the performance of a worn pump. Relatively easy to install...

 

Hi Wallyp, could you please provide the source to the piston ring?

 

OOPS! I screwed up, and looked at the last couple of messages, without rereading the entire thread. The pump piston ring is for the Airmatic System, not ABC.


My apologies.

 

No worries brother, my son has a E55 with airmatic, if you can recall the part number for that piston ring? Is it listed in EPC?

 

Here is a video of the repair.


Here are some listings on eBay. A search for Mercedes wabco will find the listings. Current cost is $23 including shipping. No affiliation, other than as a satisfied customer.
http://www.ebay.com/sch/i.html?_from...+ring&_sacat=0

 

I have some updates for the S500 ABC problem.
The ABC part of the pump was repaired, the pressure is OK now, but the power steering part was needed to be replaced (dry run resulted in damage – there was a growling noise from 1000 to 2000rpm that is gone). The serviceman told me that till now nobody had warranty issue with the repaired tandem pump.
But the ocassionally white ABC message and the missing lifting function are still have.

My experiences:

(1) If white ABC message is displayed, the RR corner is lower than it’s normal state (see the photo), the steering wheel is turned to left (and the car strongly pulls left) (see the video), there is an ESP activity on steep turns and reduced engine power is noticable
(2) If a turn-off / turn-on cycle is done after driving approx. 20km, there is a >80% chance that the ABC works again (RR corner is OK!).
(3) Till now once happens that during the driving, the white ABC message changed to red warning. After turn-off / turn on the ABC becomes OK.
(4) If the car is turned off with faulty ABC, then during the next startup the red ABC warning blinks and beeps once and car „jumps” a little (I guess due to adjusting the RR corner height) if the ABC works again (rarely happens).
(5) Once the ABC works it remains OK during the entire driving.

I think the problem could be unstable electrical connection or RR height sensor mechanical problem (loosen linkage).




Regards,
Csaba

 

Update:

Based on the servicemen's information and my measurements I found out there is no signal out from the travel/motion sensor at the FR strut (B22/5 on the known diagrams).
Is it possible to replace the sensor at home?

Regards,
Csaba