Diagnosing Power Steering Problems

Diagnosing power steering problems means looking at two things: the pump and the steering mechanism, be it a rack and pinion or recirculating ball.

The power steering pump supplies the necessary high-pressure hydraulic fluid to the steering assembly. Like any high-pressure system, leaks are the biggest problem. In automotive application, the high-pressure hose is the main concern because there is very low-pressure in the return line. Either line could leak, but the highest probability is in the high-pressure circuit.

Starting with the power steering pump, the most common problem is pump failure indicated by hard steering, a loud whining noise or leaks through the front seal behind the pulley. The only situation that has any possibility of correction is the whining or noisy pump. This is usually due to a dirty pressure regulator. By changing the fluid and adding a conditioner it can be corrected in many cases. If the noise persists after this procedure, the pump must be replaced.

The power steering pump creates a constant pressure and does not fluctuate. Given this information, if a steering situation develops that causes the steering to become difficult only at certain places through a turn or erratic or sticky, either the pump is empty due to a leak, or the steering mechanism is faulty and should be replaced.

Another common problem is leaks through the seals of the rack and pinion or the recirculating ball unit. The vehicle should be raised and these units inspected for leaks. In either case replacement is required.

A loose belt will cause the power steering pump to slip when under pressure, causing a sudden lack of pressure or steering. A belt that is to loose may work well at low rpm but slip when the rpm is raised or the vehicle encounters rain which will cause the pump to slip intermittently.

The last problem is a matter of freeplay in the steering or looseness. This occurrence is identified by movement in the steering wheel and has no effect on the steering. This is due to looseness in the steering linkage. On a rack and pinion this is due to loose tie rod ends. This can be diagnosed by raising the wheels off the ground and shaking them side to side or left to right. Any banging or looseness can be very easily identified. Replacing the inner or outer tie rod end will eradicate this problem.

In a standard recirculating ball system, any series of rods, from the drag link, idler arm, pitman arm or tie rods could be loose and again easily eradicated. To diagnose this situation, raise the vehicle and have someone rock the steering wheel to the left and right while the steering linkage is inspected. It will become apparent when watching the steering mechanism which one is loose.

Unlike the rack and pinion, this system has one adjustment for freeplay. Have a helper rock the steering wheel and watch the steering gear box pitman arm at the bottom. You can't help but notice if the exposed steering column is moving in either direction with a long delay in the pitman arm moving. It should move continuously with the steering column. There is an adjustment nut on the top of the steering gear box that can be tightened a small amount to lessen the freeplay by adding a pre-load to the sector shaft to compensate for wear. It there is not enough adjustment to rid the steering of freeplay, replace the unit.

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