brusk

I bought my 08 ML320 CDI almost a year ago and it's always felt funny with the steering. The effort is way to easy but the problem is going around turns its not smooth, the power assist seems to pulse which means you have to use to hands to take sweeping turns smooth. I also have a power steering leak somewhere as I've had to fill up the reservoir twice in the last 10K miles. I'm thinking about just replacing the rack with a re-manufactured unit. Anybody seen this before?

Maj. Dundee

Please UPDATE YOU PROFILE in USER CP.

Maj. Dundee

Why would you automatically think that it is the rack and pinion? You will have to find the origin of the leak, which includes the power steering pump reservoir & all hoses.

The O-ring between the pump and the reservoir is infamous for leaking.

brusk

I wouldn't think an oil leak would cause these type of symptoms as there's no howling or whining when you have air in the line. There are no noticeable oil leaks at the reservoir, lines, pump. I'm not sure about the rack as I did have a few oil leaks that hopefully are fixed now (lower oil pan). I know there were recalls in the past on certain MB models including the ML for internal rack leaks in the valving. I'm thinking that might be how this feels if the rack has an internal leak if it surges/pulses.

Maj. Dundee

Whenever you have to add PS fluid, you have a leak somewhere. With that, air is admitted into the system and it doesn't necessarily have to make noise.

If you feel adamant that it is the rack, then go ahead and replace it.

brusk

I wouldn't say I feel adamant about it. But what else would cause the steering feel to feel like a 70's style buick going around turns, massively overboosted. Actually my 75 Buick GS's steering feels better than the ML. Only things I can see would be excessive hydraulic pressure (which I believe is controlled at at the rack) or a valving problem letting it over power the rack. I've i'm wrong on where pressure is controlled then I could see it being a pump.

Maj. Dundee

The pulsing could be caused by a defective or leaking Y10 Valve attached to the rear of the rack. It is easily replaceable from the rear of the rack without removing the rack.

The proper part # cannot be determined unless you post your full vin#.

I suggest you have the entire veh. scanned for codes, and you will probably find code 5980-5983 stored in the ESP Control Module. Until then everything is guess work.

brusk

I'll see if my iCarsoft scanner has access to that module. So far I haven't been too impressed with it. Thanks for the info on the valve. I'll punch in my VIN and see what part number comes up.

Maj. Dundee

You should invest in this scanner.

brusk

Actually after I posted that, I forgot my roommate let me have his verus. If it stops snowing I'll scan it see what it says.

brusk

no luck on seeing any of those codes. Looked over some if the data to make sure things were reading, only thing I noticed right away was one value was moving at the engine wasn't even started yet.