Your Mercedes pulls or wanders on the straights after a turn? Could be Steering Rack-related. Here are some checks to find out if a part is worn and needs to be returned to a Mercedes Dealer.

Test Self-Centring on a Straight Road

Take an airborne run down a straight, quiet level road and at about 30mph take a slow corner. After the corner has been taken, return to a straight line road and allow the steering to return to the central position of the straight road. A good steering gear will return to centre without hesitation.

Check the Feel During Return

Check the steering feel on return to the straight line after a turn. Have someone else operate the steering wheel while you are in the driver’s seat and describe the feel as the steering is turned slowly from lock to lock. Ideally this should feel smooth and even with no ‘notchiness’, ‘stiffness’ or ‘dead spots’.

Inspect Tie-Rod Ends and Inner Ball Joints

Grasp each tie-rod end and for any signs of roughness when attempting to move them. Corroded or worn ball joints will bind within the steering rack, causing problems as the steering returns to centre. Note that inner ball joints are harder to access but may be the cause of any problems experienced with the outer ends.

Check the Rack Mounting Bushes

The common problem of steering rack mounting bushes worn to the point where the steering rack moves under load and restricts return to centre. The bushes can be checked for signs of wear around the points where the rack is mounted to the subframe.

Assess the Power Steering Fluid

Very dirty, contaminated fluid in the power steering hydraulic system creates more resistance in the system and thus hampers steering return. If the fluid in the reservoir appears dark or even shows a burnt smell, we would recommend a fluid change first.

Mercedes Steering Racks is covered in more detail at https://westernpowersteering.co.uk/vehicles/mercedes/.

It is often easier to repair a return problem early on before other wear and tear develops.