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Mercedes-Benz C-Class: How to Change Power Steering Fluid

A common complaint among w204 owners is the whining heard in the power steering system. As with all Mercedes, their systems are usually quite sophisticated and need to be in ideal working conditions to get the best of them. The power steering system is no different and needs to be topped up regularly to avoid that odd whine that emanates from in front of the firewall.

By Thomas Parry - June 25, 2015

This article applies to the Mercedes-Benz C-Class w204 (2007-2014).

Finding a proper power steering fluid for your w204 is almost as important as which reservoir you decide to dump it in. Mercedes' products are really optimized for certain kinds of fluids as well as conditions, and operate best within relatively narrow parameters. Thankfully, once the proper fluid is identified, the process isn't too difficult. Generally, this is something the attentive owner will do every 30,000 miles, or whenever the whining becomes unbearable.

Materials Needed

  • One .08-quart bottle of MBZ-approved 345 hydraulic fluid.
  • One sucking tool (turkey baster, siphoning tube, or anything else that will work)

Step 1 – Warm the car

Once the car is at its standard operating temperature, make sure to turn the car off and identify the reservoir. With the fluid hot and expanded, it will be easier to suck out with the turkey baster (or siphoning tool).

Step 2 – Remove as much fluid as possible

Turn your car off. Make sure your tool is exceptionally clean, as you don't want ANY debris getting into the steering system. Begin sucking! If you decide to use a commonly used household appliance, like a turkey baster, perhaps you should replace it to ensure domestic bliss.

Figure 1. Extract old power steering fluid with some sort of vacuum device.

Step 3 – Fill with new fluid

This might be the most important step of the process. Tantamount to finding the right fluid is making sure you're putting it in the power steering reservoir, and not in the glove box. Mercedes' recommended fluids include Chevron Texaco PSF 9109, MB 345.0 hydraulic fluid A 001 989 24 03, or Pentosin CHF 11 S Hydraulic Fluid. Anything else will simply not do. Since your car is now hot, make sure to fill up to the "80C" line. Rest easy, young warrior. The worst is over.

Figure 2. With the correct PS fluid in your command, the end is in sight.

Step 4 – Test the new fluid

Once the reservoir is filled with the new fluid, start the car and allow the fluid to circulate briefly. Once warmed, turn the steering wheel lock-to-lock several times to identify any latent whining. If the steering wheel rotates without any sort of vibration or unpleasant noise, you're in business.

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