Power steering: whining, leaking, or gone heavy

Power steering announces itself in two ways: noise and effort at the wheel. Both have simple causes worth eliminating before thinking about a new pump or rack.

Hydraulic systems

A whine on lock is the most common symptom. Causes in order of checking:

Low fluid level — the pump draws air. The cheapest and most frequent cause. Check on level ground, against the reservoir marks, at the right temperature (many cars have cold and hot marks).

Air in the system — it remains even after topping up. It is bled by turning the steering lock to lock, engine off or idling depending on the handbook.

Old fluid — dark, with a burnt smell. It lubricates worse and foams.

A blocked reservoir filter, where fitted.

A worn pump — the last hypothesis, not the first.

Where the fluid goes

The system is closed, so a falling level means a leak.

The usual places: the high-pressure hose, rack seals (wet gaiters), the pump seal, and unions.

The sign of a leaking rack: a gaiter on one side wet and swollen. That is not cosmetic — next the fluid reaches the road and the level falls.

The danger: fluid landing on the auxiliary belt destroys it; covered in the drive belt article.

Heavy steering

On a hydraulic system: low level, air, a slipping belt, a dying pump.

Suddenly and completely — a snapped belt; that is a stop, because charging goes with the steering; covered in the motorway breakdown article.

Heavier one way than the other — the rack or the control valve.

Electric systems

On modern cars assistance is more often electric: a motor on the rack or the column.

There is no fluid — so no leaks, no air-related whine, and no fluid changes.

It fails differently:

• Assistance disappears completely or intermittently — and that is a code, not mechanics.
• A voltage sag — with a weak battery the steering drops out first, being the largest consumer; covered in the parasitic drain article.
• Overheating — during prolonged manoeuvring the system temporarily reduces assistance. That is designed behaviour, not a fault.
• Steering angle and torque sensors — codes after suspension work; covered in the calibration article.

What diagnostics shows

Steering module codes — motor, torque sensor, angle sensor, temperature.

System voltage — the main cause of “suddenly heavy steering” on an electric system.

Steering angle in live data — and whether zero matches the physical position.

Codes in related systems — stability control and driver assistance use the same angle sensor.

In short

• A hydraulic whine means level or air, not immediately the pump.
• A wet swollen rack gaiter means a leak, not dirt.
• Fluid on the auxiliary belt destroys it within weeks.
• On electric systems “heavy steering” often means a voltage sag.
• Temporarily reduced assistance during manoeuvring is designed behaviour.

Download the app — steering module codes, steering angle, and voltage are read with an ELM327 adapter over Bluetooth SPP on Android.