12.4 Steering System Maintenance

Maintenance of the steering system consists of regular inspection, lubrication, and adjusting components to compensate for wear. When inspecting the steering system, you will need someone to assist you by turning the steering wheel back and forth through the free play while you check the steering linkage and connections. You will also be able to determine if the steering mechanism is securely fastened to the frame. A slight amount of free play may seem insignificant, but if allowed to remain, the free play will quickly increase, resulting in poor steering control.

After prolonged use, steering components can fail. It is important that the steering system be kept in good working condition for obvious safety reasons. It is your job to find and correct any system malfunctions quickly and properly.

Steering Linkage Service

Any area containing a ball-and-socket joint is subjected to extreme movements and dirt. The combination of these two will cause the ball-and-socket joint to wear. When your inspection finds worn steering linkage components, they must be replaced with new components. Two areas of concern are the idler arm and the tie-rod ends.

Idler Arm Service

A worn idler arm causes play in the steering wheel. The front wheels, mostly the right wheel, can turn without causing movement of the steering wheel. This is a very common wear point in the steering linkage and should be checked carefully.

To check an idler arm for wear, grab the outer end of the arm (end opposite the frame) and force it up and down by hand. Note the amount of movement at the end of the arm and compare it to the manufacturer’s specifications. Typically, an idler arm should NOT move up and down more than 1/4 inch.

The replacement of a worn idler arm is as follows:

  1. Separate the outer end of the arm from the center link. A ball joint fork or puller can be used to force the idler arm’s joint from the center link.
  2. With the outer end removed from the center link, unbolt and remove the idler arm from the frame.
  3. Install the new idler arm in reverse order of removal. Make sure that all fasteners are torqued to manufacturer’s specifications. Install a new cotter pin and bend it properly.

Tie-Rod End Service

A worn tie-rod end will also cause steering play. When movement is detected between the ball stud and the socket, replacement is necessary.

The replacement of a worn tie-rod end is as follows:

  1. Separate the tie rod from the steering knuckle or center link. As with the idler arm, a ball joint fork or puller can be used.
  2. With the tie rod removed from the steering knuckle or center link, measure tie- rod length. This will allow you to set the new tie rod at about the same length as the old one.

 

Note

The alignment of the front wheel is altered when the length of the tie rod is changed.

  1. Loosen and unscrew the tie-rod adjustment sleeve from the tie-rod end. Turn the new tie-rod end into the adjustment sleeve until it is the exact length of the old tie rod.
  2. Install the tie-rod ball stud into the center link or steering knuckle. Tighten the fasteners to manufacturer's specifications. Install new cotter pins and bend correctly. Tighten the adjustment sleeve and check steering action.

Manual Steering System Service

Steering system service normally involves the adjusting or replacement of worn parts. Service is required when the worm shaft rotates back and forth without normal pitman arm shaft movement. This would indicate that there is play inside the gearbox. If excess clearance is NOT corrected after the adjustments, the steering gearbox must be replaced or rebuilt.

Manual gearbox adjustment--Since there are numerous steering gearbox configurations, we will discuss the most common type, re-circulating ball and nut. There are two basic adjustments: worm bearing preload and over center clearance.

Worm bearing preload--Assures that the worm shaft is held snugly inside the gearbox housing. If the worm shaft bearings are too loose, the worm shaft can move sideways and up and down during operation.

Over center clearance--Controls the amount of play between the pitman arm shaft gear (sector) and the teeth on the ball nut. It is the most critical adjustment affecting steering wheel play.

 

Note

Set the worm bearing preload first and then the over center clearance. Basic procedures for adjusting worm-bearing preload are as follows:

  1. Disconnect the pitman arm from the pitman arm shaft.
  2. Loosen the pitman arm shaft over center adjusting locknut and screw out the adjusting screw a couple of turns. Then turn the steering wheel from side to side slowly.
  3. Using a torque wrench or spring scale, measure the amount of force required to turn the steering wheel to the center position. Note the reading on the torque wrench or the spring scale and compare it to the manufacturer’s specifications.
  4. If readings are out of specifications, loosen the worm-bearing locknut. Then tighten the worm bearing adjustment nut to increase the preload. Loosen it to decrease preload and turning effort. With the preload set to specifications, tighten the locknut. Make sure the steering wheel turns freely from stop to stop.

 

Note

If the steering wheel binds or feels rough, then the gearbox has damaged components and should be rebuilt or replaced.

Basic procedures for adjusting the over center clearance are as follows:

  1. Find the center position of the steering wheel. This is done by turning the steering wheel from full right to full left while counting the number of turns. Divide the number of turns by two to find the middle. This allows you to turn the steering wheel from full stop to the center.

 

Note

Most gearboxes are designed to have more gear tooth backlash (clearance) when turned to the right or left. A slight preload is produced in the center position to avoid steering wheel play during straight-ahead driving.

  1. With the steering wheel centered, loosen the over center adjusting screw locknut. Turn the over center adjusting screw in until it bottoms lightly. This will remove the backlash.
  2. Using the instructions in the service manual, measure the amount of force required to turn the steering wheel. Loosen or tighten the adjustment screw to meet the manufacturer’s specifications. Tighten the locknut and recheck the gearbox action.

When adjustment fails to correct the problems, the steering gearbox needs to be overhauled or replaced. Overhauling a gearbox is done by disassembling, cleaning, inspecting, and replacing worn components and seals. After reassembling the gearbox, fill the housing with the correct type of lubricant. Most manual steering systems use SAE 90 gear oil. Make sure that you do NOT overfill the gearbox. Refer to the manufacturer's service manual for the particular gearbox you are working on since procedures, specifications, and type of lubricants vary.

Rack and Pinion Service

Rack and pinion steering systems have few parts that fail. When problems do develop, they are frequently in the tie-rod ends. When NOT properly lubricated, the rack and pinion will also wear, causing problems.

Depending upon the manufacturer, some rack-and-pinion steering systems need periodic lubrication. Others only need lubrication when the unit is being reassembled after being repaired.

Most rack-and-pinion systems have a rack guide adjustment screw. This screw is adjusted when there is excessive play in the steering. Basic procedures for adjusting rack-and-pinion steering system are as follows:

  1. Loosen the locknut on the adjusting screw. Then turn the rack guide screw until it bottoms slightly. Back off the rack guide screw the recommended amount (approximately 45 degrees or until the prescribed turning effort is achieved).
  2. Tighten the locknut. Check for tight or loose steering and measure steering effort. Compare with the manufacturer's specifications. If not within specifications, an overhaul of the system will be required.
  3. For instructions on the removal/installation and overhaul of the rack-and-pinion system, refer to the manufacturer’s service manual for the equipment you are repairing.

Power Steering System Maintenance

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

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:

  1. Unscrew and remove the cap to the power steering reservoir. The cap will normally have a dipstick attached.
  2. 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.

 

Note

The fluid level will rise on the dipstick as the steering system warms.

  1. If required, add only 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.

 

CAUTION

Do NOT overfill the system. Overfilling will cause fluid to spray out the top of the reservoir and onto the engine and other components.

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.

 

CAUTION

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. Pry ONLY on the reinforced flanged or a recommended point.

Basic procedures for installing a power steering belt are as follows:

  1. Loosen the bolts that hold the power steering pump to its brackets.
  2. Push inward on the pump to release tension on the belt. With the tension removed, slide the belt from the pulley.
  3. Obtain a new belt and install it in reverse order. Remember: when adjusting belt tension to specifications, pry only 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:

  1. 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.
  2. 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.
  3. Close the shutoff valve to check system pressure. Note and compare the pressure reading with manufacturer’s specifications.

 

CAUTION

Do NOT close the shutoff valve for more than 5 seconds. If the shutoff value is closed longer, damage will occur to the power steering pump from overheating.

  1. To check the action of the power piston, control valves, 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

Anytime 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.

Troubleshooting Steering Systems

The most common problems of a steering system are as follows:

These problems normally point to component wear, lack of lubrication, or an incorrect adjustment. You must inspect and test the steering system to locate the source of the trouble.

Steering Wheel Play

The most common of all problems in a steering system is excessive steering wheel

play. Steering wheel play is normally caused by worn ball sockets, worn idler arm, or too much clearance in the steering gearbox. Typically, you should not be able to turn the steering wheel more than 1 1/2 inches without causing the front wheels to move. If the steering wheel rotates excessively, a serious steering problem exists.

An effective way to check for play in the steering linkage or rack-and-pinion mechanism is by the dry-park test. With the full weight of the vehicle on the front wheels, have someone move the steering wheel from side to side while you examine the steering system for looseness. Start your inspection at the steering column shaft and work your way to the tie-rod ends. Ensure that the movement of one component causes an equal amount of movement of the adjoining component.

Watch for ball studs that wiggle in their sockets. With a rack-and-pinion steering system, squeeze the rubber boots and feel the inner tie rod to detect wear. If the tie rod moves sideways in relation to the rack, the socket is worn and should be replaced.

Another way of inspecting the steering system involves moving the steering components and front wheel by hand. With the steering wheel locked, raise the vehicle and place it on jack stands. Then force the front wheels right and left while checking for component looseness.

Hard Steering

If hard steering occurs, it is probably due to excessively tight adjustments in the steering gearbox or linkages. Hard steering can also be caused by low or uneven tire pressure, abnormal friction in the steering gearbox, in the linkage, or at the ball joints, or improper wheel or frame alignment.

The failure of power steering in a vehicle causes the steering system to revert to straight mechanical operation, requiring much greater steering force to be applied by the operator. When this happens, the power steering gearbox and pump should be checked as outlined in the manufacturer's service manual.

To check the steering system for excessive friction, raise the front of the vehicle, and turn the steering wheel and check the steering system components to locate the source of excessive friction. Disconnect the pitman arm. If this action eliminates the frictional drag, then the friction is either in the linkage or at the steering knuckles. If the friction is NOT eliminated when the pitman arm is disconnected, then the steering gearbox is probably faulty.

If hard steering is not due to excessive friction in the steering system, the most probable causes are incorrect front end alignment, a misaligned frame, or sagging springs.

Excessive tire caster causes hard steering. Wheel alignment will be described later in this chapter.

Steering System Noises

When problems exist, steering systems can produce abnormal noises (rattles, squeaks, and squeals). Noises can be signs of worn components, un-lubricated bearings or ball joints, loose components, slipping belts, low power steering fluid, or other troubles.

Rattles in the steering linkage may develop if linkage components become loose. Squeaks during turns can develop due to lack of lubrication in the joints or bearings of the steering linkage. This condition can also produce hard steering.

Some of the connections between the steering linkage components are connected by ball sockets that can be lubricated. Some ball sockets are permanently lubricated on original assembly. If permanently lubricated ball sockets develop squeaks or excessive friction, they must be replaced.

Belt squeal is a loud screeching sound produced by belt slippage. A slipping power steering belt will usually show up when turning. Turning the steering wheel to the full right or left will increase system pressure and belt squeal. Belt squeal may be eliminated by either adjusting or replacing the belt.

Test your Knowledge

4. When you perform a pressure test on a power steering system, the shut-off valve should NOT be closed for more than how many seconds?

A. 20
B. 15
C. 10
D. 5