[Cowiepeters]

Eighteen months ago, while in the dealership for other work, I was told that the ABC pump had failed. Apparently the car had sunk over a week or so and wouldn't lift up.

They quoted $8000 for the pump and $1500 to install it.

I said I'd think about it and ordered one from parts.com for $1250.

When I told the dealer that I would get my own pump they told me that the car had lifted itself up and everything was OK.

So, I have a brand new pump in an MB Box.

Soon after I got the ABC Drive Carefully message and there was a puddle under the car after a 30 minute drive and the ABC reservoir was wet all around.

I cleaned it up, replaced the filter and did a flush using the lift switch to lift the car up and down.

Everything has been fine until the weekend when, after about 30 minutes of driving around the suburbs I got the ding and ABC Visit Workshop message. When I tried to lift the car with the button nothing happened except for the red death screen ABC Drive Carefully. I drove the 15 minutes home and tried lifting the car a few times with no result.

The car did not sink on the way home but the ride was a bit harsh over speed humps and wallowed at speed

After an hour in the garage I started it up and everything's fine: it lifts up and down no problems, no error messages

Fine yesterday for two 15 minute drives but did the same thing this morning after 20 minutes... ding and message and no lift. Fine when I returned 30 minutes later and on the 30 minute drive home.

When I got home there is a puddle where it usually sits and the ABC reservoir and all around it is wet.

I cleaned it all up and lifted the car up and down 20 times without problem.

Unfortunately my SDS does not talk to the ABC module so I can't check for codes.

It sounds like intermittent pump failure but in my mind a pump either works or it doesn't.

If it has failed and is providing low pressure through wear how can it then function perfectly and repeatedly lifting the car 20 times in quick succession?

The leak at the reservoir is a bit weird... it sounds as if too much fluid is being returned but the fluid level is at the right mark and I can't repeat the leak.

The car has 131,000km and it would be relatively straightforward to replace the pump but I'd like to know that it was definitely the problem before I went ahead and started replacing things like a dealer

I'd appreciate any advice

Thanks

 

[stclarke]

I had similar issues shortly before I put the car away for the winter. I trust my Indy mechanic, but I was also having trouble understanding why sometimes everything would be fine and at others I'd get the RED warning... that was until he hooked up the Star Diagnostic computer to my car and showed me the BAR (pressure) levels within the ABC system.

We ran the rodeo, turned the car on and off a number of times, drove it around for a while, let it sit for a while etc.. and to my surprise, sometimes the BAR pressure was at 0 (zero) others at 200 and at others started at 0 and slowly moved up to 200. According to my Indy, all signs of a pump starting to fail..

Now, I didn't have any fluid leaks such as yourself, but sounds like your pump given my own personal experience.

I've looked around for pumps and they can be had from anywhere between $1250 and $2000.00 CDN new or @ $700 rebuilt, and my Indy quoted @ $700 for the install, flush, fluid etc.

Hope this helps,

-Stephen

 

[Cowiepeters]

A big help

That's a big help thanks,

I am fairly sure that it is the pump but I just wanted to see if anyone else had experienced similar issues.

I didn't want to be like a dealer and just throw expensive parts at it until I ran out of money

The pump is sitting in it's box and I'll probably book it in early next week with my trusted independent mechanic (Ross Firth City Star Motors Sydney)

Thanks

 

[m60kaf]

I'm not sure why a pump would produce pressure then not. I would have thought a pump fails it fails

Intermittent more likely to be a faulty electric bypass valve screwed to pump?

Incidentally I have found if ABC totally bottoms out the reservoir overflows

 

[Cowiepeters]

ABC Gremlin fixed

The problem got worse over the next day or so until I had a continual white message and the odd red message.

The car would still lift itself up and down when cold

My mechanic replaced the pump but had big problems accessing a very difficult torx bolt down the back of the pump. It had rusted and took him hours to remove.

He trained with Benz 30 years ago and does a good job but he said if anyone could do it in three hours he'd happily give it to them

I'm glad I didn't do it

He had some trouble when he started the car as it wouldn't build any pressure but eventually everything worked.

It gave a white warning on the way home and another when I drove it to work the next morning and it's been perfect since.

My new STAR system arrived last week and I finally have it all working except for XENTRY

It accesses the Chassis modules and I was able to clear a code (low pressure, presumably from the warning on my drive to work) and rodeo the car, just for fun

All is good in the world again

 

[Cowiepeters]

What's inside the ABC Tandem Pump

I don't like knowing how things work and why they fail so I pulled the old pump to bits today to find out.

I have to admit to a bit of butchery as I was unable to remove the drive flange after several attempts despite various seemingly clever tries include unscrewing, heat, a puller and brute force. It finally succumbed to the ministrations of an angle grinder.

It's a very clever pump.

The back of the pump is the power steering pump and it is a small vane pump. Simple and long lasting with most wear being taken up by centrifugal force. I don't know of many failures of this sort of pump, they seemed to last longer than most cars.

The front end is the ABC pump and I expected to find a duplicate of the power steering pump here but its a seven piston radial pump similar to that in an older diesel engine but the pistons are in a circle. Power steering pumps generate about 1000psi but the ABC system generates 180bar or about 2800psi.

The photos show what's inside and how it works. It's a beautiful bit of machinery and I don't know how they can sell one for $1200.

Interestingly, there are no ball bearings in the pump, just hardened journals and shafts.

There are a number of places where I could identify where the failure might arise:

The pistons are hardened steel inside a hardened steel bore. The tolerances are tiny and there are no seals. Eventually wear occurs in the bore and bypass occurs. This is what I consider to be the most likely reason for a pump to fail as the mileage increases. Similar things happen to diesel fuel injection pumps (and those mechanical fuel injection pumps used on older Benzes) Diesel pumps can be refurbished with new pistons and ground bores but I don't think that this technique would be applicable to the ABC Pump unless spare parts were available to a specialist.

The Low and High pressure sides of the pump are separated by o-rings and they could fail. The o-rings in my pump looked OK

The outlet valves could become worn and allow leakage... they are pretty small and I don't believe they could be refurbished without new parts

The shaft seals could leak but they are on the low pressure side of the pump and won't cause a pressure fault but would lead to fluid loss and eventual pump failure

The tolerances in the pistons and cylinders of the pump are negligible to enable a seal to occur without any form of rubber or secondary mechanical device. I seem to recall that they are in the region of a tenth of a thousandth of an inch. The pistons in my pump measured .5020" and the bore .5028. That's more than a running fit. and I am going to place my money on wear in the pump pistons and bore as the cause of the failure.

The negligible clearances in the pump highlight the importance of fitting the new fine filter and changing the ABC fluid regularly.

There are bound to be experts out there with differing opinions but I thought it would be interesting to identify the cause of so much grief that will happen to all of us if we keep our cars for more than a few years

 

[Cowiepeters]

What's inside the ABC Tandem Pump... More Photos

More photos:

 

[Cowiepeters]

What's inside the ABC Tandem Pump... More Photos

Final Photos

 

[Richrider]

Great explanation and photos, this is a complicated pump. Especially interesting were the radial arrangement of the pistons. I need to replace my pump as the low side seal is leaking. I was going to purchase a rebuilt pump. After reading your analysis I was wondering if it is possible to adequately rebuild a worn pump that looses pressure. It seems that new pistons would be required, which is the critical area of wear. Has anyone used a rebuilt pump with success/

 

[theintelligent1]

Has anyone used a rebuilt pump with success/

there is a thread on the other forum in the AMG CL 216 section which shows a rebuild of the ABC pump using this o ring kit:
Mercedes Benz ABC Pump Seal Kit MBZABCSEALKIT

would be interesting to hear other succesful rebuilds.......

 

[Cowiepeters]

Successful ABC Pump Rebuild???

The seal kit that is available for $90 may well fix pump that is leaking externally but cannot correct a worn pump as I have described.

Given that you have to pull the pump out, dismantle it, reassemble it and fit it... and it might not work I'd say just go to parts.com and buy a brand new one in a Mercedes Box for $1224

The only identification on my failed pump for age was a date on the pressure sensor of something 03, so the pump is probably original. It's got 131,000km or about 80,000 miles on it which is consistent with what others have observed

If you car has around that number of K's and you get similar symptoms I'd recommend you put a new pump in

I suspect that the "rebuilt" pumps might be just the sealing kit.

Good Luck

 

[theintelligent1]

The seal kit that is available for $90 may well fix pump that is leaking externally but cannot correct a worn pump as I have described.

If you car has around that number of K's and you get similar symptoms I'd recommend you put a new pump in

I suspect that the "rebuilt" pumps might be just the sealing kit.

Pretty much agree with this........would only be worthwhile even considering a seal kit if it was a pretty obvious there were perished seals etc......bearings etc is a whole other story......

There is also the reservoir cover which sometimes leaks (assuming usually a mass/quick leak) which can be bought from the same place.........about 40 bucks or so.....

Would be interesting to know what is used in the so called rebuilt pumps on ebay......there are some german workshops online who seem to have much more knowledge on rebuilding the pumps but without any first hand experience who knows.......

 

[Dadunn06]

Very helpful comments. My pump needs replacing and I was quoted 1700 for the part, but seems like 1200-1300 more the going rate. Someone mentioned parts.com as a place to order. Any other suggestions? Thanks in advance

 

[Cowiepeters]

ABC Pump

Parts.com had a good price. They have stopped shipping outside the US which is a pain

I'd repeat my previous suggestion that you would be wasting your time and money to put a refurbished pump in the car. The "refurb kit" appears to be only seals and gaskets and that is not where the wear is likely to have occurred.

The $600 you save with a refurb is going to get blown away when you have to take it out again and put a new one in

Good luck

 

[Gary Knox]

Cowiepeters,

The failure of the pump after about 80K miles causes me to wonder about the service history on the ABC hydraulic fluid. Do you know if it was ever flushed and replaced with new MB fluid or Pentosin CHF 11S? Do you know when the original filter was changed to a 3 mm filter? That kind of 'maintenance" information could be very helpful to others.

I have 46K on my '03 SL55, and can find no indication of service, but it does have the 3 mm filter. The fluid is no longer green, but a medium tan color. I will do a flush/replacement with Pentosin fluid before driving it this spring. I am also trying to install the aftermarket filter produced the the German company that has developed thorough service procedures for the ABC system that in at least one case has resulted in 230K km without any parts replacement except for one hose. (see sticky at the top of the forum - article on the "importance of ABC fluid change" for further info).

Thanks for any insight you can give us.

Gary Knox

 

[Cowiepeters]

ABC Pump

I've had the car for 5 years and it had 80,000km/ 48000 miles on it when I bought it

I flushed the fluid and put a new filter in at 100,000km 60,000 mles. The fluid was slightly brown

I don't know what the service hostory of the fluid/ filter was prior to my ownership

Hope this helps

Peter

 

[Gary Knox]

Thanks Peter. It sounds like flushing at about 35-40K miles may be best. Mine has more than that, but had the new filter (when installed, there is no record), and I'll certainly flush before it gets driven again.

Gary-

 

[select12]

Eighteen months ago, while in the dealership for other work, I was told that the ABC pump had failed. Apparently the car had sunk over a week or so and wouldn't lift up.

They quoted $8000 for the pump and $1500 to install it.

I said I'd think about it and ordered one from parts.com for $1250.

When I told the dealer that I would get my own pump they told me that the car had lifted itself up and everything was OK.

So, I have a brand new pump in an MB Box.

Soon after I got the ABC Drive Carefully message and there was a puddle under the car after a 30 minute drive and the ABC reservoir was wet all around.

I cleaned it up, replaced the filter and did a flush using the lift switch to lift the car up and down.

Everything has been fine until the weekend when, after about 30 minutes of driving around the suburbs I got the ding and ABC Visit Workshop message. When I tried to lift the car with the button nothing happened except for the red death screen ABC Drive Carefully. I drove the 15 minutes home and tried lifting the car a few times with no result.

The car did not sink on the way home but the ride was a bit harsh over speed humps and wallowed at speed

After an hour in the garage I started it up and everything's fine: it lifts up and down no problems, no error messages

Fine yesterday for two 15 minute drives but did the same thing this morning after 20 minutes... ding and message and no lift. Fine when I returned 30 minutes later and on the 30 minute drive home.

When I got home there is a puddle where it usually sits and the ABC reservoir and all around it is wet.

I cleaned it all up and lifted the car up and down 20 times without problem.

Unfortunately my SDS does not talk to the ABC module so I can't check for codes.

It sounds like intermittent pump failure but in my mind a pump either works or it doesn't.

If it has failed and is providing low pressure through wear how can it then function perfectly and repeatedly lifting the car 20 times in quick succession?

The leak at the reservoir is a bit weird... it sounds as if too much fluid is being returned but the fluid level is at the right mark and I can't repeat the leak.

The car has 131,000km and it would be relatively straightforward to replace the pump but I'd like to know that it was definitely the problem before I went ahead and started replacing things like a dealer

I'd appreciate any advice

Thanks

Do you know where I can get parts for the pump

The cap that holds the spring in