Date registered: Jul 2005
Vehicle: 90 300E, 99 ML430, 00 ML320, 05 E500 4matic Wagon
Mentioned: 18 Post(s)
Quoted: 886 Post(s)
Above the steering pump there is a black plastic reservoir with a cap on it. The cap has a dipstick built into it.
If you find it is low only use MB fluid or MB approved brand.
Next is that it is a sealed system and should not be losing any so you need to check for a leak.
Most common is the base of the reservoir o-ring. New o-ring, clip and reservoir is about $35.
I beg that you bring this issue down to the W163 forum here and you will find many DIY threads on fixing it if that is leak.
If it is not leaking it needs to be checked to make sure the latest recall was done for potential hose clamp failure. They can leak from where that hose is clamped.
Please bring your questions down to the W163 forum. If the pump is running low on fluid or dry it is eating itself up.