ASE A4 Suspension and SteeringSteering System Diagnosis and RepairMedium
A client complains that their vehicle's steering wheel is difficult to turn only when the engine is cold, but eases up after the vehicle has been driven for several minutes. The power steering fluid level is full and appears clean. Which of the following is the MOST probable cause?
- AA partially collapsed power steering return hose.
- BIncorrect power steering fluid type or viscosity.
- CExcessive internal wear in the steering gear.
- DA worn power steering pump flow control valve.
Show answer & explanationAnswer & explanation
Correct answer: B. Incorrect power steering fluid type or viscosity.
If steering is only hard when cold and improves as the fluid warms up, it strongly suggests an issue with the fluid's viscosity. Using the wrong type of power steering fluid (e.g., too thick for cold temperatures) or contaminated fluid can lead to this symptom. Once the fluid warms and thins, it flows more easily, reducing steering effort.
Why the other options are wrong
- A. A partially collapsed return hose would cause increased pressure and heavy steering at all times, not just when cold.
- C. Excessive internal wear in the steering gear would cause consistent heavy steering or a 'dead spot' regardless of fluid temperature.
- D. A worn flow control valve would typically cause consistent heavy steering or inconsistent assist at all temperatures, not just when cold.
Cold-Dependent Hard Steering
When hydraulic power steering is stiff only when cold and improves as the engine warms, the most likely cause is incorrect power steering fluid type or viscosity, which affects fluid flow at low temperatures.
- Fluid viscosity changes with temperature.
- Wrong fluid can be too thick when cold.
- Check fluid specification against manufacturer recommendations.
Memory trick: Cold makes the fluid thick, like molasses.