Heavy Steering At Low Revs – What’s The Reason?
Symptom: The power steering is hard to turn with the engine at idle but turns easily when the engine revs are increased to 2,500 – 3,000 rpm. This problem can affect vehicles with hydraulic steering systems with belt driven or gear driven hydraulic power steering pumps.
Cause: The power steering pump is not providing sufficient pressure to operate the power steering rack/box correctly at engine idle revs. Most power steering pumps create pressure by forcing the power steering fluid into smaller space using rotating vanes or cylinders. The efficiency of the pump is determined by the proportions of the fluid allowed to leak passed these vane or cylinders. As these components wear more fluid leaks passed reducing the efficiency of the pump. Increasing the speed the vanes or cylinders are rotating compensates for the loss of efficiency.
Solution: The power steering pump needs to be replaced. A remanufactured power steering pump has these worn components replaced with components that are within original manufactures tolerances, hence reducing fluid leakage passed these internal components.
Tip: When trying to diagnose a vehicle with heavy power steering, a good test is to hold the steering wheel on a lock at the point that it is just about to turn; rev the engine to 3,000rpm and if the steering turns without any additional force applied to the steering wheel then the most likely problem is a worn power steering pump.