The Evolution of Power Steering

These systems have come a long way but still require regular maintenance.

undercar steering power steering power steering maintenance vehicle maintenance repair shop training technician training automotive aftermarket Steering assist and control is one of the many systems we have seen continually change and evolve over the years. All of the OEMs have invested millions of dollars into the advancement of steering controls.

We, as technicians, have seen simple manual gear boxes replaced by hydraulic ones. We've seen gear boxes, or sectors, give way to rack and pinion assemblies that operate with more advanced hydraulics. And now, electronic steering systems are not uncommon.

Not only do we have to continually learn new material as these systems come to market, but we have to maintain our knowledge of past and present systems. Whatever the age of the system or how advanced it might seem, regular inspection and maintenance is the common factor they all share and need to work properly.

Pieces, Parts and Components at a Glance

With steering being such a safety related aspect, and with such a high demand placed on this part of a vehicle, inspection of the steering and suspension system on every vehicle should be a priority.

An important thing to look at first, of course, is the hardware. It takes very little time to do a good, thorough inspection of steering components when you have a customer's vehicle in the air. Don't be afraid to grab a tire at the top and bottom and give it a good flexing in and out to make sure a hub and bearing assembly doesn't have excessive play. Bearings carry a lot of weight and pressure and should be checked on a regular basis.

Almost no play at all should be felt in a sealed hub and bearing assembly. Tapered bearings should be cleaned, lubricated and properly adjusted for preload to prevent overheating and bearing failure.

Upper and lower ball joints are a must for inspection. Many are sealed and have no accessible grease fittings for service. These take quit a beating. Not only are they the pivot point for the front steering knuckles, but they also endure a ton of lateral force. Always inspect the boots for splitting or damage and make sure to check for play in both upper and lower joints. To accurately test ball joints for wear, be sure to follow the specific procedure outlined in your service information system for the vehicle you are working on. Some vehicles use visual indicators; some require specific lifting procedures to "unload" the joints for inspection.

Tie rod ends, both inner and outer, should be checked in much the same way. Inspect the boots and check for excessive play or wear. Most vehicles can be checked by grabbing each wheel at the 9 and 3 o'clock positions, and attempting to rock the wheel back and forth. If any noticeable movement is felt, use one hand to grab the outer tie rod assembly to see if it is the cause of the play. If not, grabbing the tie rod shaft will allow you to feel any movement that may exist in the inner tie rod joint.

Steering systems that use a drag link or center link set up with idler and pitman arms should be inspected just like the tie rod ends. Wear in these components can have some serious safety concerns and cause excessive tire wear. Always make sure that any of these parts having fittings for service are properly lubricated. Do not overfill the grease boots, as this will lead to rupture and premature failure of the components.

If the system is hydraulic, always inspect for leaks. Whether it's a rack and pinion or worm gear and sector type unit, both operate under high pressures. Pressures can exceed 1,000 psi in many systems, and a leak can deplete the system of fluid rapidly. Make sure hoses and lines are routed properly and away from exhaust components or moving parts.

Make sure to look at compression fitting, as well as connection to power steering pumps and gears, for leaks. Always inspect pumps for leaks at case seams and shaft seals and make sure to maintain the correct level of fluid in the reservoir.

If the pump is belt driven, inspect the belt for wear or damage. Listen for unusual noise from the pumps as compared to a like vehicle. A noisy pump is a definite indication of a problem whether it's a failure or something like air being induced into the system that can lead to a failure. Air being pulled into a system can cause an excessive whine and can lead to premature pump failure if not addressed.

Of course the driver's feedback for the entire system is the steering wheel. Always inspect the steering shaft from the gear back up to the column no matter what the design. Most systems entail a series of universal joints, slip yokes, crush shafts or some type of intermediate steering shaft that leaves the gear and connects to the column. This is the last thing you want to fail on a curvy stretch of highway at 65 mph. Most of these are manufacturer specific and require very little in the area of maintenance, except for inspection, but are a vital part of the steering system. The column itself should be checked for freedom of rotation to make sure there is no loose play in the column bearings.

Electric power steering systems will usually have an integral column and an electric assist design. These systems are usually replaced as an assembly and will not likely have serviceable components in the column except for the electric components themselves. With that being said, they should still be inspected as any other column design.

Service is Still the Answer

As with any other system on the vehicle, we know power steering needs service as well. There are many serviceable hard parts in any steering system, but with good routine maintenance, most components will last for a long time. Our customers have to be educated on the need for regular service to a system like power steering.

Pivot points and fittings should always be lubricated or greased at regular service intervals. Pinch points or steering stops should be lubricated as well. And of course let's not forget about that fluid in the hydraulic systems. These fluids are under very high pressures and operate at extremely high temperatures. Even though the fluids are designed for this kind of environment, viscosity and thermal breakdown can and will occur. The fluid can begin to burn and break down, and as components in the system degrade where the fluid travels, contaminants begin to build up in the fluid.

Should these fluids be serviced like any other fluid in the vehicle? Absolutely. It takes only a few minutes to pull a sample of fluid from a system and inspect it for burning and contamination. If they're present, it's probably a good time to flush, clean and refill the system.

There are many good systems on the market for flushing and cleaning power steering systems. Some systems will connect right into the vehicle power steering system, while others simply extract and reintroduce fluid or cleaners right through the fluid reservoir.

There are also some pretty good conditioning products that come along with these systems as well. With the advent of high quality synthetic power steering fluids, you can offer your customer an even better choice when it comes to fluids operating under extreme conditions. With these products we can offer a good service that can save customers a lot of money and give them peace of mind.

Randy Wilson is an ASE Master Technician currently working for a Chevrolet and Cadillac dealership in Dothan, Ala. He is Advanced Engine Performance Specialist Certified with 25 years of experience under his belt. Wilson specializes in drivability, diagnostics and electrical systems.