Let’s get under the skin of the checks made during a power steering diagnostic in more detail. What does the mechanic actually do?

Fluid Condition and Level

The condition of the fluid and its level is checked. Fluids that are low or appear to be dirty may need to be topped up but in most cases a simple top up will not cure the problem. If the fluid is dirty or degraded it will cause premature wear to the pump and rack.

Pressure Testing

By attaching a pressure gauge to the hydraulic circuit of the vehicle, the mechanic can determine if the power steering pump is producing the correct amount of pressure. The pressure will drop if the pump or the relief valve is failing, whereas the rack will not be affected by a failing pump or relief valve.

Rack and Pinion Play

The specialist checks for wear by rocking the steering wheel when the engine is running. The amount of slack in the steering column will indicate whether the rack bushes are worn or if there is wear within the rack itself.

Pump Noise and Output

The sound of the pump whining or even groaning while it is running is checked at idle as well as from lock to lock. Here we are checking for cavitation. Cavitation indicates worn bearings in the pump or aeration of the fluid due to a slow leak.

Steering Sensor Checks on Electric Systems

In addition to the checks already mentioned, on electric power steering equipped vehicles the torque sensor is tested for correct output signal. This can trigger a warning light to appear and result in the power steering assistance cutting in and out erratically rather than failing completely.

Power Steering Specialists is covered in more detail at //westernpowersteering.co.uk.

Knowing what each check involves makes understanding the full diagnosis and the correct repair even easier.