KeithBoden

When I bought my 2003 S600, it was making a few vibrating and whining sounds. One turned out to be the water pump bearings, which was replaced after it locked up and melted the belt and a few of the idler pulleys. Upon fixing those issues, the whining remained.

One day I was driving, and heard a high pressure hose in the ABC system blow. At the same time, my vibrating/whining noise went away. Success! I already knew that the o-rings in the valve blocks needed replaced, and that the car would slowly be losing height with the pump not making pressure. From other threads, I also heard that it isn't hard to destroy the ABC pump following a high pressure hose/fluid loss. However, I drove the car another 20 miles till I was in a good place to have the car towed home.

I wasn't happy to be going back into the same area a week later, after just having the fan, belt, airboxes, etc. off to do the water pump, I also had the high pressure lines unclamped from the crossmember, but failed to notice the hack job that occurred in the past to the pulsation damper hose. The steel line that does the U bend was cut off and welded shut.

I bought a new hose, 220-320-59-72, and started with the replacement. After removing the reservoir and lifting the engine a little, I ran into a roadblock with the banjo bolt. Someone had tried removing it before and had rounded it off. It seems they made an effort to replace the hose, but then took a shortcut when they couldn't get the banjo bolt off. (This explains why so much stuff was broken on the drivers side; there was definitely a butcher working on this car at one point.)

I managed to get the banjo bolt out by lifting the engine really high, and by using a 3/4" 6-point socket. I filed the bolt back to a hex shape, and the rest of the hose replacement went smoothly. By the way, I decided not to try to pre-fill the pulsation damper hose with fluid. The WIS information didn't say to do it, and air in the hose may be a part of the operating design.

I refilled the reservoirs (pentosyn in the PS reservoir, Mobile-1 in the ABC,) followed the PS air removal procedure of turning the wheels back and forth with the engine off, and pressurized the ABC reservoir before startup. No pressure. I was getting fluid out of the return hose, but the DAS said "0 bar" pressure, and the suspension was on the floor.

I read up on how the system regulates the pressure, and the next day, revised my pressurizing hoses, and bumped the pressure up from 15psi to about 20. I started the engine, and the system pressurized! 190 bar! On to the rodeo test!

At first, the rodeo test was not working well. The front left corner wouldn't raise like the others, and the pressure would drop down to 120 bar. Even after a few minutes, the front left was no better. Thinking there might still be air trapped somewhere, I ran the 'roll' actuation test instead for a minute, which cycles the left and right sides up and down alternately, with a little bounce in the middle. It could have been a coincidence, but with the front left immediately started coming to life.

Welwynnick

It's really great to hear about people are fixing their ABC problems, rather than throwing money at it, but I'm not sure Mobil 1 should go in the suspension. I think it ought to be CHF-11S of one brand or another.