The power steering pump on the Mercedes is a very well made pump but like all things mechanical can and will wear out over time. If you are seeing leaking fluid from around the pump area make sure to inspect the O-ring on the rear of the reservoir before replacing the pump.Now I want to share the guide on how to replace power steering pump for Benz W204.
Applies to:C350 (2007-14), SLK350 (2004-14), CLS350 (2004-14), CLK350 (2005-14), E350 (2005-14), S350 (2005-14), SL350 (2005-14), R350 (2006-14), ML350 (2006-14), Viano (2005-14), Sprinter (2006-14), CLC350 (2008-14), GLK350 (2008-12)
Time: 4 hours
Tab: $320 to $1,300
Talent: 3 Tools: 22mm wrench, E12 socket, T30 Torx, flathead screwdriver, pliers,fluid pump
Parts Required: Pump, power steering fluid, crush washers
Hot Tip: Keep everything really clean
Performance Gain: Proper steering Complementary Modification: Bleed system
Procedures:
The power steering reservoir and pump are located on the front left of the motor (red arrow).To replace it you will need to remove the two-air inlet ducts as well as the front engine cover (yellow arrows).Please see my article on engine cover removal:How to Remove Benz C Class W204 Engine Cover
You may want to remove the front trim cover for additional room.To remove the cover turn the plastic lock (yellow arrow) 90 degrees to un-clock it.Remove the overflow and cable release from the cover (red arrow).Then pull forward on the cover on each side (green arrows) and lift the rear of the cover up and remove it.
Carefully clean the area around the fill cap on the reservoir.Open it and use a fluid pump to suck as much fluid as you can from the reservoir (red arrow).No matter how good a job you do of removing the fluid there will still be some left when you remove the reservoir,so be prepared for it.
Use a quarter-inch drive T30 Torx and remove the three bolts (red arrows).The bolts will remain in the reservoir housing after you unscrew the from the motor.
The reservoir is mounted to the return line of the pump and held in place by a clip.The clip is difficult to see when installed and impossible to photograph.Reach in behind the pump and insert a flathead screwdriver and pry the clip off (red arrow).Next,pull the reservoir off the pump.
With the reservoir removed you can see where it attaches to the pump and approximately where the clip goes to hold it in place (red arrow).Always replace the O-ring after you have removed the reservoir (yellow arrow).
Place the reservoir off to the side,and be prepared to catch the fluid that will spill out.You do not need to disconnect the line unless you are replacing the reservoir as well (red arrow)
The power steering pump is located below the reservoir (red arrow).The pump will be removed with the pulley attached.Begin by removing the high-pressure line (yellow arrow).Note:I have removed the oil filter cooler and housing for photographic purposes only.You do NOT need to remove these to perform this work
Always replace the two crush washers on each side of the banjo fitting (red arrows) and make sure everything is clean.Even the small amount of dirt shown in this photograph can damage the power steering system.Use an E12 socket and remove the three bolts holding the pump to the mount (red arrow).The bolt on the rear is difficult to access.If you need more room you can disconnect the A/C compressor from its mount and lower it out of the way;just make sure you do not disconnect the lines.
With the mounting bolts removed turn the pump over while being prepared for fluid to spill out and disconnect the ground wire from the back using an E12 Torx socket (red arrow).
Always install a new O-ring on the fitting between the pump and reservoir (red arrow) and insure the cleanliness of the banjo-fitting opening (red arrow);even a small amount of dirt or debris can affect the performance or cause damage to the system.Installation is the reverse of removal.Please see my article on how to properly fill and bleed your power steering system.Failure to properly fill and bleed th system can result in damage.
Done!