There are two types of steering systems. The old heavy gearbox was the only system many years ago, but now, all front wheel drive cars and minivans, even some full-size trucks use the "rack and pinion" which is very lightweight and simple, but the seals do leak at times. The steering shaft could leak power steering fluid inside the car by your feet, but this is not common. The two steering linkages are where the seals usually leak. This assembly is quite inexpensive compared to the older gearbox. Most rebuilt assemblies run around $150.00 to 200.00, more for GM and Ford units. Power steering fluid is pressurized to well over 1100 pounds of pressure to push the power piston back and forth as dictated by the movement of the steering wheel. The question should be "how do those seal keep that much pressure in as well as they do?"
This system is called a rack and pinion because the rack is a simple straight flat bar with teeth cut into it, and the pinion is a round toothed gear turned by the steering wheel and shaft that moves the rack back and forth to move the steering linkages.
One note for our friends who haven't heard it yet: You do NOT lose your steering when the engine dies while you're still moving. The pressurized power steering fluid comes from the pump which is driven by the running engine. When the engine dies, the steering gets very hard due to the lack of power assist, but it will still steer. The sudden change in steering effort causes some people to panic and think the steering is locked up because that change is so severe. With the ignition switch unlocked, try turning the steering wheel before you start the engine. You'll see how hard it feels, but then, keep in mind that a rolling car steers much easier than one standing still. The main reason for power steering is low-speed turns and parking. Some cars actually reduce or eliminate power assist on the highway, in part, for better fuel economy.
Turning the steering wheel back and forth excessively without the engine running, such as when inspecting the car for a suspension-related noise, will cause power steering fluid to be pushed out of the pump reservoir and onto the ground, giving the appearance of a major leak. This is common. All you can do is refill the system and turn the steering wheel back and forth with the engine running to burp the air out. Air in the system, including when there is a leak, will cause a buzzing noise that increases in pitch as the engine speeds up.
Another common problem with rack and pinion assemblies is called "morning sickness". This is where there is no power assist in only one direction the first minute or two after starting the engine. Internal seals are worn and leaking, but the fluid does not leak out where it can be seen. As the power steering fluid warms up, the seals expand and seal better so the power assist comes back. In a month or two, the other direction is affected too. This problem is extremely common on GM vehicles within the first 40,000 miles, but is seldom seen in Chrysler products. After-market rebuilt rack and pinion assemblies are modified to prevent this from happening again. The parts that wear and leak were made of soft aluminum; the modified parts are built with stainless steel.
Two years and 46,000 miles is real soon to be having trouble with a Chrysler rack and pinion. Do you think it's leaking because of a puddle behind the front tires when you park, or did someone tell you there's a leak? If you have had to add fluid, there probably is a leak. When you take it in for an oil change, they will add power steering fluid if necessary, but good mechanics will check for the reason it was necessary to add. My 1988 Caravan only needed a little fluid added once in its 210,000 miles. Manufacturers are always looking for ways to reduce cost, so many parts aren't of the same quality as 20 years ago, but it is still not common to have a leaking Chrysler rack and pinion assembly in less than 100,000 miles, so if you weren't having a problem, you should consider getting a second opinion.
Friday, March 27th, 2009 AT 2:55 AM