Mercedes-Benz E420 Rack and Pinion Replacement Cost

The steering rack is located between the front wheels, and attaches them to the steering wheel. The inner and outer tie rod ends link the ends of the steering rack to the steering knuckles, which is what the car's wheels attach to. When the steering wheel is turned, the steering rack forces all of these components out on one side, and pulls them in on the other side.

Rack-and-pinion problems typically come with the following symptoms:

Power steering fluid leaks

A whining or clunking noise when turning the steering wheel

Difficulty steering at low speeds, or a loose sensation when turning the wheel

» LEARN MORE: How your steering system works

Small power steering leaks won't prevent the vehicle from driving, but when fluid cannot be added quickly enough to keep the pump full, a tow truck is recommended to avoid damaging the fuel pump and steering gear.

As any system that carries high pressure will, the system will eventually fail from normal wear and tear, but this should be well into the serviceable life of the vehicle. For most vehicles, the power steering system will last well over 100,000 miles before any failures occur. Keeping the power steering fluid fresh and the system free of contaminants is key to ensuring long power steering system life. That's why sticking to your regularly scheduled maintenance, detailed in your owner's manual, is so important.

Since most power steering issues generate the same symptoms, it can be difficult to diagnose one part without checking the condition of the whole system. A technician will check for leaks, examine the belt tension and listen for problems with the power steering pump. If these all check out. After that, if no other issues are found, the steering rack will be suspected of failure, if the symptoms dictate. 

Replacing the steering rack involves a fair amount of disassembly — fluid must be drained, hoses and electrical connectors must be removed, and the rack has to be unbolted from the car. Replacement is the opposite order of operations, followed by standard fill and bleed procedures for power steering systems.

Power steering components are subject to high pressure, high heat and high speeds. Using parts that are built to meet or exceed OEM standards will help ensure the longevity of the power steering system. Inferior parts tend to lead to repeated replacement. 

Rack-and-pinion steering systems should be replaced by a professional technician. Many modern vehicles require removal of the front sub-frame while supporting the engine from the upper frame rails. This is a dangerous operation made much more safe when performed on a lift, with proper bracing equipment.