Many of the components of a power steering system are the same as those used on a manual steering system. However, a pump, hoses, a power piston, and a control valve are added. These components can also fail. requiring repair or replacement. Power steering system service typically consists of the following:
Checking power steering fluid level
Checking belts and hoses
CHECKING POWER STEERING FLUID.- To check the level of the power steering fluid, you should NOT let the engine run. With the parking brake set, place the transmission in either PARK or NEUTRAL. Basic procedures for checking the level of the power steering fluid are as follows:
Unscrew and remove the cap to the power steering reservoir. The cap will normally have a dipstick attached.
Wipe off the dipstick and reinstall the cap. Remove the cap and inspect the level of the fluid on the dipstick. Most dipsticks will have HOT and COLD markings. Make sure you read the correct marking on the dipstick.
The fluid level will rise on the dipstick as the steering system warms.
If required, only add enough fluid to reach the correct mark on the dipstick. Automatic transmission fluid is commonly used in a power steering system. Some power steering systems, however, do NOT use automatic transmission fluid and require a special power steering fluid. Always refer to the manufacturer's service for the correct type of fluid for your system.
SERVICING POWER STEERING HOSES AND BELT.- Always inspect the condition of the hoses and the belt very carefully.
The hoses are exposed to tremendous pressures; if a hose ruptures, a sudden and dangerous loss of power assist occurs. Make sure that the hose is NOT rubbing on moving or hot components. This can cause hose failure.
Power steering pump pressure can exceed 1,000 psi. This is enough pressure to cause serious eye injury. Wear eye protection when working on a power steering system.
If it is necessary to replace a power steering hose, use a flare nut or tubing wrench. This action will prevent you from stripping the nut. When starting a new hose fitting, use your hand. This action will prevent cross threading. Always tighten the hose fitting properly.
A loose power steering belt can slip, causing belt squeal and erratic or high steering effort. A worn or cracked belt may break during operation, which would cause a loss of power assist.
When it is necessary to tighten a power steering belt, do NOT pry on the side of the power steering pump. The thin housing on the pump can easily be dented and ruined. ONLY pry on the reinforced flanged or a recommended point.
The basic procedures for installing a power steering belt are as follows:
Loosen the bolts that hold the power steering pump to its brackets.
Push inward on the pump to release tension on the belt. With the tension removed, slide the belt from the pulley.
Obtain a new belt and install it in reverse order. Remember when adjusting belt tension to specifications, only pry on the reinforced flange or a recommended pry point.
POWER STEERING LEAKS.- A common problem with power steering systems is fluid leakage. With pressure over 1,000 psi, leaks can develop easily around fittings. in hoses. at the gearbox seals, or at the rack-and-pinion assembly.
To check for leaks. wipe the fluid-soaked area( s) with a clean rag. Then have another person start and idle the engine. While watching for leaks, have the steering wheel turned to the right and left. This action will pressurize all components of the system that might be leaking. After locating the leaking component. remove and repair or replace it.
POWER STEERING PRESSURE TEST.- A power steering pressure test checks the operation of the power steering pump, the pressure relief valve, the control valve. the hoses. and the power piston. Basic procedures for performing a power steering pressure test are as follows:
Using a steering system pressure tester, connect the pressure gauge and shutoff valve to the power steering pump outlet and hose. Torque the hose fitting properly.
With the system full of fluid, start and idle the engine (with the shutoff valve open) while turning the steering wheel back and forth. This will bring the fluid up to temperature.
Close the shutoff valve to check system pressure.
To check the action of the power piston. control valve. and hoses, measure the system pressure while turning the steering wheel right and left (stop to stop) with the shutoff valve open. Note and compare the readings to the manufacturer's specifications. If the system is not within specifications, use the manufacturer's service manual to determine the source of the problem.
BLEEDING A POWER STEERING SYSTEM.- Any time you replace or repair a hydraulic component (pump. hoses, and power piston), you should bleed the system. Bleeding the system assures that all of the air is out of the hoses, the pump, and the gearbox. Air can cause the power steering system to make a BUZZING sound. The sound will occur as the steering wheel is turned right or left.
To bleed out any air, start the engine and turn the steering wheel fully from side to side. Keep checking the fluid and add as needed. This will force the air into the reservoir and out of the system.