ABC leak
 

I couldn't leave well enough alone and ran a rodeo test on my 2003 SL. Everything was fine but later in the day, just when I was pulling into the garage, the red ABC warning went on. There is fluid dripping down just behind the driver's front wheel as well as in the center behind the engine. It appears to be a major leak. I checked the reservoir and surprisingly it is over full. Any ideas??

Obviously the fluid is feeding back into the reservoir. And that is probably the result of the fluid leak behind the DS front wheel. An overflow from the reservoir. Center behind the engine? IDK. But it needs to go on a lift to have a good look underneath to find the source of the leak.

If it was me, I would at least manually run through the ABC switch a few times to see if the fluid level in the reservoir might correct itself...or you need to add some fluid to make up for what drained out. Maybe another rodeo? Nothing to lose??? Just don't let the pump run dry. If you cannot get it to normalize you need to get it towed to the shop. And you need to get to the bank.

Knowledge...
 

Read this about 3 times until it sinks in...
http://mercedes-abc-drive-carefully....y-part-of.html
Don't be afraid to wrench it if required.

Great write-up. Thanks for posting that. I bookmarked it.

Well, I woke up this morning hoping I had a bad dream but unfortunately the system really does have a problem. This write-up is excellent and tends to point to an accumulator. I'm going to check the reservoir and see if the fluid is really backing up upon shut-off being carefull to not let it get low when I start it--I have a few cans of fluid handy. If that isn't it, I'll pull the closeout panel and see if there is a leak. Judging by the puddle on the floor it is a major leak or overflow and the closeout is hiding the exact location. More to come. Thanks for the suggestions !

The fluid is also flammable. Make sure it's not leaking onto anything hot, like the exhaust.

It looks like I'll have it up on a hoist tonight. Judging by the amount of fluid leaking, I doubt it will take much effort to find the source ! I put some fluid in the reservoir so I could move it and it drips out slowly without the engine running. When I start it, it pours out. I'm making sure I don't run the pump dry. The cheapest price I find for the pentosin is at Amazon. 5L for $86 same day delivery and tax. I got 1 jug just to get the diagnosis going.

Well, I got it up on a hoist and pulled the lower closeout panels. The leak is the front seal of the pump assembly. It looks like the seal blew out since the fluid runs out from behind the pully as you pour fluid into the reservoir. I'm going to remove the pulley with the pump in place and suspect I will see the seal completely out of the bore. I'm sure the rodeo test created some high pressures but I'm not ruling out that an accumulator burst causing a pressure spike. The system never leaked a drop so it was a catastophic seal failure. I think I can repair it without even removing the pump.

Update:


I removed the pump and the leak is from the big O ring around the metal housing. However, turning the pump by hand, it tends to lock up or bind once in a while. I never ran it dry and I also noticed that the reservoir overflowed when I first discovered the leak, so I'm assuming the pump is toast. I'll have it apart tomorrow since I'm using a press to get the flange off. So, I ordered a new pump from Amazon and will install it. It's such a bear to R&R that I just want to get it over with and not experiment with rebuilding the current one. I notice that Cardone seems to be the major rebuilder but I can't find one in stock so I'll spend $990 at Amazon (with no core needed) for a new one. Cardone does offer a rebuilding service for less than $300 but you have to send in your defective pump. It's a good price but I don't want to wait that long.

Installed the new pump and all is well.