Has my ABC pump *really* failed?

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2003SL55

New Member
Joined
May 13, 2010
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8
Car
2003 SL55
80000 miles 2003 SL55.

- Front struts replaced about 8000 miles ago by main dealer under warranty, with all fluid replaced and new filter fitted.
- ABC warning light came on around 3000 miles ago but a rodeo test sorted it out.
- Car serviced at main dealer 1200 miles ago in November 09
- Car not used left standing outside in freezing weather for all of Feb and March
- On startup, ABC car too low warning, Merc Assistance attended
- Star diagnostic plugged in and reported:
--Control unit FEDERUNG
--C1525-001 Critical vehicle level front left
--C1525-064 System pressure too low
--C1526-016 Malfunction in pressure supply
--Possible cause and remedy
--Component Radial piston pump is defective

Roadside wanted to call a truck and have the car taken to dealer for new pump to be fitted. I had an idea of what this might cost from a main dealer so declined.

I want to make sure it is the pump that is faulty before forking out 965 for the pump plus whatever seals, hoses, filters, fluid and labour go with the job.

The Pentosin reservoir has a dipstick. There is no max/min marking but there are two horizontal lines roughly halfway along the dipper so I guess these are max/min. The level in the fluid is way below this, right at the bottom of the dipstick. The engine bay isn't sparkling but there is not a great mess elsewhere in the vicinity of the ABC pump or any of the tyres/wheelarches so I am thinking a slow leak rather than any catastrophic sudden loss of fluid.

I understand an electric pump can burn out but this is a belt driven pump, and spins fine when the engine runs without making any alarming noise. There is a gap between the tyres and the wheel arch just large enough to get your fingers in, and the steering turns lock to lock with about 2 mm clearance of the wheelarch so definitely not driveable.

I'm looking for the following advice if anyone can help please:

1) First thought is to top up this reservoir with fluid (which I will source from main dealer). Is this a safe thing to do or should I not start the engine (and hence run the pump) until a professional has looked at the car?

2) Even if something in the system is leaking, would a top up of the reservoir be likely to get the car raised long enough to allow it to be driven the 20 miles or so to the independent workshop I want to look at it.

3) The indie I want to use is an audi specialist and I am advised there is a similar high pressure hydraulic suspension system on some Audis. Is it wise/unwise to take this problem to someone who is not a Merc dealer/specialist and is a star diagnostic/Rodeo test likely to be needed? I want to use this particular mechanic because he is a personal friend and I can trust him not to lie to me about work needed, unlike some of the main dealers I have used who in my opinion are nothing short of fraudulent.

Thanks for any advice.
 
It will need STAR regardless of which direction you take - main dealer or specialist. Hard to tell as to the problem - ABC is a common fault as are the leaking struts as you've found out. Unless you know what to look for you could be replacing expensive items needlessly. Get an indy to diagnose if possible - if you're on the south coast then PCS is a no-brainer.
 
I can help if you need any advice. It does look like the ABC pumphas had it. VERY common failure.
 
It's worth pointing out that if ignored it can get worse. The car has front and rear valves that maintain the high pressure - if the pump fails and sends gubbins around the circuit (filter is on the return line) then you can spend the same again replacing each valve block.
 
What features does a dead pump have? Obviously it's spinning so is there some internal part that is prone to disintegration or does it simply leak?

Am I right about the desired fluid level being around the centre of the dipstick? There is no obvious leak in the vicinity of the pump so where has all the fluid gone?

What do the experts here think about topping the reservoir and starting the car up?

Any recommendations for trustworthy specialists much appreciated. Location is Warwickshire, about 30 miles south east of Birmingham. Can pump be replaced in situ or does it require ramps/clean room?
 
update... have just put a litre of fluid in

Suspension raised immediately, car raises and lowers using button on centre console. Now to see how long it stays raised for and where any leak is coming from.
 
Get it to a specialist or dealer ASAP. The longer you leave it the more you risk permanent damage.
 
Yep will get it inspected tomo if I can to find where the leak is. Am I right in thinking this system doesn't just lose fluid overtime? I put a litre in and its to the top mark on the dipstick now so I guess it was missing something around 1/2 to 3/4 litre previously. I wouldn't put it past the dealer who replaced the struts not filling it correctly at that time judging from past experiences with them. It was a reluctant choice to go to them - when Merc Assist came they gave me the choice of taking the car to my home or the nearest dealer.
 
Yep will get it inspected tomo if I can to find where the leak is. Am I right in thinking this system doesn't just lose fluid overtime? I put a litre in and its to the top mark on the dipstick now so I guess it was missing something around 1/2 to 3/4 litre previously. I wouldn't put it past the dealer who replaced the struts not filling it correctly at that time judging from past experiences with them. It was a reluctant choice to go to them - when Merc Assist came they gave me the choice of taking the car to my home or the nearest dealer.

Consider taking it to a local indi, Howard Williams Ltd in Moseley, or Wayne in Perry Barr.
 
update.. after topping up the ABC reservoir, the car was on ramps and thoroughly inspected. No signs of any leaks. Have since driven best part of 1000 miles with no probs and checking the ABC reservoir dipstick each morning. The fluid level hasn't dropped a millimetre. Glad I didn't take their word for it and commit to a 4 figure job.
 
You would do well to listen to stats on this, the fluid went somewhere originally, and these things rarely get better on their own!
 
Assuming the fluid was there in the first place.....
 
Well, I for one support the wait and see approach. Clearly if there are not puddles under the car and the "at rest" level of the fluid is constant, then whatever it is, is happening slowly over time. Black marker pen + line + date and inspect daily for changes. If the level goes down then a trip to the garage is called for. If the car rose after adding fluid then the pump is working - no? There is either a leak or not enough fluid was present to start with.
 
help

Well, I for one support the wait and see approach. Clearly if there are not puddles under the car and the "at rest" level of the fluid is constant, then whatever it is, is happening slowly over time. Black marker pen + line + date and inspect daily for changes. If the level goes down then a trip to the garage is called for. If the car rose after adding fluid then the pump is working - no? There is either a leak or not enough fluid was present to start with.

nobody has said any thing about the markings on the dip stick ? I now have the same problem red light on then goes off! turn off the car look at the dipstick and its low then go back to the car later to find the oil at the first mark am i low on oil ? star says its pump pressure low reset and its ok until the next day can any one help before a put oil in?
 
iirc, These cars run on nitrogen spheres. Spheres will lose pressure and absorb more oil, so the system will require an occasional top up as it only has a small reservoir.
 
I wonder what Andrew ( Stats ) is up to, miss his expertise and his two penneth worth of course.
 
Driving my 2008 CL63 last week and a nasty noise started coming from the engine and the ABC malfuntion light came on on the dash, drove the car to the local Merc dealer, I took the tech guy out for a drive round the block, left the car in the garage for further inspection, got a call the next day, the ABC pump was knackered, £2000 to replace with a 12 day wait for the parts to arrive from Germany!!! sick, only had the car 6 months, first Merc, always had M Power BMW's (only takes BMW 48 hours to get parts shipped in from Germany)
 

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