There are a number of issues that can cause your vehicle to have steering problems, but one of the most specific components you should be regularly checking is your idler arm.
In parallelogram steering linkage systems, which are the most common form that vehicle steering racks take, the idler arm is one of three pieces that fit between four tie rods to make up the parallelogram shape.
(While the parallelogram system is most common, there are some vehicle steering linkages that employ two idler arms. Make sure you know how your vehicle is put together to be sure you're checking for the cause of your symptoms appropriately.)
While the counterpart to an idler arm, the pitman arm, attaches to the steering gear and transfers the motions of the actual steering wheel to the center link, tie rods, and ultimately the front wheels; the idler arm is a reflection of that. It acts as a pivoting support on the passenger side of the vehicle, so it attaches to the opposite end of the center link and transfers steering motion to the passenger side of the vehicle.
Once you understand the large role that the simple idler arm plays, it's easier to get an idea of where things can go wrong. If the following problems or changes arise in your vehicle handling, they could point back to an idler arm that is damaged or malfunctioning.
1. Road Walking
Also known as road wandering, this scary phenomenon occurs when a vehicle seems to wander or weave back and forth on its own. If you are being attentive and steady on the steering wheel but are experiencing road walking, it will be genuinely difficult for you to keep the vehicle straight.
2. Play in the Wheel
If you have suspicions that the idler arm is in poor condition, this symptom can be tested under safer and easier conditions than road walking. While the vehicle is sitting still, try moving the steering wheel. If you can move the wheel considerably from side to side without much resistance, your steering wheel has too much play. While you certainly don't want your car to be unresponsive when you make steering maneuvers, a wheel that has too little resistance is also bad and a sign that the idler arm is your problem.
3. Free Wheeling
This symptom can only be observed and tested in a garage or mechanic setting, as the car must be raised so that the front wheels are suspended off of the ground.
- Always use suggested and available safety equipment when working underneath a vehicle.
While the vehicle is raised, go to your front wheels and without manipulating the steering wheel at all, see if it's possible to move the front wheels from side to side. If the wheels do shift back and forth, it's a sign that you should look into the idler arm.
It is true that because your car's steering assembly is made up of so many interlinking parts, problems can arise that are entirely independent of your idler arm. However, because the idler arm is such a specific component, it's helpful if you can diagnose it as the problem on your own and save a mechanic the trouble and cost.
Even when you don't suspect a problem with your idler arm, regular care will keep it working well. For example, idler arms are often installed with grease fittings. During routine oil change, use the opportunity to lubricate idler arm grease fittings with a grease gun.