This bulletin applies to 2010 Mercedes-Benz CLK350 models. If you receive customer reports of flow noises from the area of the power steering pump and/or foaming of the power steering fluid in the reservoir following work carried out on the hydraulic steering system, this may be caused by an improper procedure that was followed for fluid filling and bleeding of the hydraulic power steering system.
To remedy, it is absolutely necessary to make sure that the procedure described in the WIS is strictly adhered to. In particular, it is necessary to turn the steering to full lock-to-lock at least 30 times before starting the engine. If this is not done prior to starting the engine, there is a high risk of air entering the steering system, which is very difficult to eliminate.
Starting the engine prior to bleeding can cause irreparable damage to the power steering pump and will cause an air cushion to form in the steering gear which causes noise. Once the air is ingested, the air will only dissipate after driving the vehicle for more than 30 miles.