The procedures for maintaining, adjusting and repairing the power steering system and its components are to be performed only after determining that the steering linkage and front suspension systems are correctly aligned and in good condition. All worn or damaged parts should be replaced before attempting to service the power steering system. After correcting any condition that could affect the power steering, do the preliminary test of the steering system components.
Proper lubrication of the steering linkage and the front suspension components is very important for the proper operation of the steering systems of vans equipped with power steering. Most all power steering systems use the same lubricant in the steering gear box as in the power steering pump reservoir, and the fluid level is maintained at the pump reservoir.
With power cylinder assist power steering, the steering gear is of the standard mechanical type and the lubricating oil is self contained within the gear box and the level is maintained by the removal of a filler plug on the gear box housing. The control valve assembly is mounted on the gear box and is lubricated by power steering oil from the power steering pump reservoir, where the level is maintained.Air Bleeding
Air bubbles in the power steering system must be removed from the fluid. Be sure the reservoir is filled to the proper level and the fluid is warmed up to operating temperature. Then, turn the steering wheel through its full travel three or four times until all the air bubbles are removed. Do not hold the steering wheel against its stops. Recheck the fluid level.Fluid Level Check
- Run the engine until the fluid is at the normal operating temperature. Then, turn the steering wheel through its full travel three or four times, and shut off the engine.
- Check the fluid level in the steering reservoir. If the fluid level is low, add enough fluid to raise the level to the FULL mark on the dipstick or filler tube.
Inspect the pump belt for cracks, glazing, or worn places. Using a belt tension gauge, check the belt tension for the proper range of adjustment. The amount of tension varies with the make of truck or van and the condition of the belt. New belts (those belts used less than 15 minutes) require a higher figure. The belt deflection method of adjustment may be used only if a belt tension gauge is not available. The belt should be adjusted for a deflection of 1 / 4 - 3 / 8 in. (6.35-9.53mm).Fluid Leaks
Check all possible leakage points (hoses, power steering pump, or steering gear) for loss of fluid. Turn the engine on and rotate the steering wheel from stop-to-stop several times. Tighten all loose fittings and replace any defective lines or valve seats.Turning Effort
Check the turning effort required to turn the steering wheel after aligning the front wheels and inflating the tires to the proper pressure.
- With the vehicle on dry pavement and the front wheel straight ahead, set the parking brake and turn the engine on.
- After a short warm-up period for the engine, turn the steering wheel back and forth several times to warm the steering fluid.
- Attach a spring scale to the steering wheel rim and measure the pull required to turn the steering wheel one complete revolution in each direction. The effort needed to turn the steering wheel should not exceed the limits specified.
This test may be done with the steering wheel removed and a torque wrench applied on the steering wheel nut.Power Steering Hose Inspection
Inspect both the input and output hoses of the power steering pump for worn spots, cracks, or signs of leakage. Replace hose if defective, being sure to reconnect the replacement hose properly. Many power steering hoses are identified as to where they are to be connected by special means, such as fittings that will only fit on the correct pump fitting, or hoses of special lengths.Test Driving to Check the Power Steering Operation
When test driving to check power steering, drive at a speed between 15 and 20 mph. (24-32 km). Make several turns in each direction. When a turn is completed, the front wheels should return to the straight ahead position with very little help from the driver.
If the front wheels fail to return as they should, and the steering linkage is free, well oiled and properly adjusted, the trouble is probably due to misalignment of the power cylinder or improper adjustment of the spool valve.