Power Steering Rack Problems and Replacement Tips
While most of us take it for granted, the power steering system is a critical component of your vehicle. Eventually, the parts that comprise the steering system will wear out. External components, such as the tie rod ends and links wear out much faster than the internal components, so you will experience servicing those parts regularly. The internal components, which include the hydraulics and steering rack & pinion unit, last much longer, so servicing those items is a fairly rare occurrence.
When you do have to service the internal system, it must be done right. The most common failure is a broken line. This is easily replaced at no detriment to the rest of the system. If the pump fails, however, the likelihood of further damage is very good. When a power steering pump fails, there is usually a good amount of metal shavings sent through the lines. The shavings wreak havoc on the valves and seals, which means that the power assist function will quickly die, and possibly take out the new pump as well if it is not replaced at the same time.
Replacing the steering rack is not physically difficult, but there are a few steps that you need to take in order to ensure that it is done correctly and that the repair lasts. Cleanliness is the key to a steering rack replacement. If you aren’t a DIYer, your local NAPA AutoCare Center will be able to manage this job with ease.
Common Steering Rack Problems
The most common failure in a steering rack is the seals. Most steering racks use O-rings to seal the internal components. There are two separate systems at work inside a power-assist rack & pinion: the hydraulics (power assist), and the mechanics (steering). The two systems share the pinion gear inside the upper portion of the main housing. The pinion gear runs through the hydraulic servo. As the pressurized fluid runs through the valve, any movement of the pinion gear (which is connected to the steering column) rotates the spool valve to line up with the correct flow ports. When the steering wheel is centered (neutral position), the fluid bypasses the spool valve. The spool valve directs the pressurized fluid to the appropriate side of the assist piston inside the long tube of the steering rack. This provides the assist for steering. There are numerous lines and valves that need an O-ring seal. Because they are under severe pressures exceeding 2000 psi, they are prone to failing.
The mechanics of the rack are certainly more simple, but nonetheless capable of failing. The pinion gear rides on the rack (which is attached to the piston). There is a mesh setting, this can be get out of alignment through wear or physical damage, and cause hard or loose steering. Some racks have the steering shafts coming out of the end of the unit, over time these can get damaged or even strip out the threads, which requires complete replacement of the steering rack unit.
Tips For Steering Rack Replacement
It is possible to rebuild the seals on a steering rack, but the process is lengthy and the deeper internal seals are more difficult to change without special tools. Replacement is typically the most cost effective solution. The process for replacing a rack typically takes 4-6 hours, make and model variances differ or course. Removing the rack involves disconnecting the steering linkage, removing the tie rods, disconnecting the hydraulic lines, and then the rack itself. There are two types of rack mounts- bushed lugs or clamps. This rack shown below (from a 2009 Dodge Challenger) uses the bushed lug style. Here is the rack itself. Note the two large lug bosses just to the inside of the bellows. These are the rack mounts. This is an end-steer rack, where the steering arms come out of the ends. The other style of rack is center steer, where the steering arms are mounted to a tie rod bar.
The installation is a reverse of the removal, in the same order, with the exception of the hydraulics. Those need to be cleaned up first. Now is the time to inspect the lines for cracks, bulges or weak spots that could cause issues in the future. If in good shape, each line must be thoroughly flushed with brake cleaner if they are to be reused.
For external reservoir systems, like this one, the reservoir must be cleaned out as well. We sprayed this with brake cleaner, blowing it out with compressed air and then repeated several times. Installing a magnetic inline filter for the return line of the system is a good idea. The filter goes in the return line from the rack to the reservoir. This works for both external and internal reservoir pumps.
With the new rack installed and connected, it is filled new power steering fluid and purged. To purge the air from the system, the steering wheel is turned 15-20 times lock to lock with the engine off. At this point, the engine was started and the system was working properly. Within the next few miles, some additional air pockets will likely be dislodged, lowering the fluid level in the reservoir, so it should be checked for several days and additional fluid added as needed.
Any time the steering system is modified, the vehicle must be aligned. Some NAPA AutoCare Centers can do this in-house, some do not. This is not a small issue, failure to have your front suspension aligned will cause erratic handling and permanent tire wear damage within a 100 miles. By taking the proper steps, your new steering rack will last many years of service and get you back on the road.
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