RProsser

Hello friends. I have a 2005 SL55 AMG with 52K miles.

Over the last few months I have noticed a curious thing happening with the Pentosin fluid levels between the ABC tank and the power steering tank. It was this: every week or so after some occasional spirited driving, I will find that the power steering fluid level is way too low and the ABC fluid is way too high -- to the point that the fluid burps-out and makes a mess on the driveway or garage floor.

Case-in-point: Two weeks ago, I had the fluid levels perfect (while cold, and yes I know about the two levels on the ABC dipstick). Then, yesterday after driving, the above happened again. This is probably the third time now. This morning, while the car was cold, I pulled FIVE turkey basters worth of Pentosin out of the ABC tank and put it into the power steering tank. Result was the levels were perfect again, so that seems to indicate that there is a relationship between the two fluid circuits. The only place I can think of that being is in the pump.

So two questions for the gurus on this site:
- Is there any other place these two circuits could intermix other than the pump?
- If not, is this a classic indication that the pump needs to be replaced?

Thanks very much for your input.

kbob999

This is a tough question.

Yes, the same pump pressurizes the ABC and the PS, but i would think the ABC would be much higher pressure than the PS.
This would mean if there is a bad seal between the two sides of the pump, the fluid would move to the PS side, not the ABC.

I'm not an expert, so I could be wrong on the pressures from the pumps. Hopefully someone with experience on this same problem can weigh in.

You may be due for accumulators, as they are more than 10 years old. Mileage does matter, but so does age with these.
I'd first check the one downstream from the pump. If it is bad, you need to do the other 3.

RProsser

Thanks kbob999. Hadn't considered that there are/may be two different pressures. That makes sense.

BTW, two of the accumulators have been changed, but not the rear one -- yet.

Wish I could make sense of this before I just jump into the pump replacement project, i.e., hate to change it just to find the problem still persists.