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Mercedes-Benz C-Class and C-Class AMG: Why is My Power Steering Noisy?

Mercedes has developed a sophisticated power steering system, but along with the technology comes quirks. Fixing this little problem does not require much time or effort - just a little attention.

By Thomas Parry - June 4, 2015

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

As you're backing your car out, you notice a whine emanating from underneath the hood. This shrill, irritating noise increases in volume as the steering wheel is turned and at full lock, a slight vibration is noticeable. Fortunately, this is nothing more than a power steering pump whining due to low fluid. While many will be thrown off by a Mercedes making this kind of noise, it is very common across their line of models – particularly the C-class. When at full lock, the system is aerating the fluid which is what is responsible for vibration. The pressure relief valve is what makes that whining noise.

Materials Needed

  • Mercedes-Benz approved power steering fluid (meeting 236.3 spec)

Step 1 – Turn on car, let engine idle

Sometimes with cold fluid, you may get a whine that isn't indicative of the actual problem at hand.

The problem at hand may be that the fluid is simply too cold and once it warms, you should notice a mild reduction of the whining noise.

Step 2 – Turn your steering wheel lock-to-lock at least five times

This action should help bleed the system of any air bubbles, which may be the culprit.

Figure 1. Turn the steering wheel all the way to each side.

Step 3 – Pull the RHS air pipe

The thick black air pipe on the right hand side of the engine covers the power steering reservoir. Pull this back to expose the reservoir and unscrew the cap.

Figure 2. Remove the air intake pipe.

Step 4 – Top up the power steering fluid

Unscrew the cap and fill to the desired level. Take note of the hot and cold levels on the dipstick attached to the power steering reservoir cap.

  • Figure 3. Accessing your power steering fluid.
  • Figure 4. Note the correct level marks.

Mercedes-Benz only uses high grade power steering fluid. Please take note of the kinds listed within the owner's manual, which can be bought at a dealership. Do not mix this with off-the-shelf brands.

The following brands are acceptable for use in Mercedes engines, as taken from the service manual:

Fuchs Titan PSF - Fuchs Petrolub AG, Mannheim/Deutschland
Gulf ATF MX - Gulf Oil International, London/ENGLAND
Liqui Moly LENKGETRIEBE- ÖL 3100 - Liqui Moly GmbH, Ulm/Deutschland
MB 236.3 Lenkgetriebeöl - P/N A 000 989 88 03 Daimler AG, Stuttgart/Deutschland
Megol Lenkgetriebeoel Stability - Meguin GmbH & Co. KG Mineraloelwerke, Saarlouis/Deutschland

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