How to Diagnose a Bad Idler Arm
If you feel too much play in the steering wheel, steering wheel shimmy, shake, or vibrate loosely while driving, it might be from a bad idler arm. Some trucks and older vehicles use a reciprocating ball steering system, also known as a drag link set up, which includes a steering box, pitman arm, idler arm, and a control rod that sits in the middle and connects to the inner and outer ball joints. There is a ball joint on the pitman arm and the idler arm, and sometimes it can fail. These steps will show you how to diagnose it.
Symptoms of a Bad Idler Arm
1. Steering Wheel Shimmy
A steering wheel with too much play that shimmies, shakes, or vibrates too loosely can be a symptom of a bad idler arm. Poor steering likely means the ball joints are worn.
2. Drifting While Driving
If you feel the vehicle pull or drift to one side or another or back and forth while driving, there could be an issue with the idler arm.
3. Play in the Wheel
If you raise and secure the vehicle and you can feel the wheel move loosely from the 3 and 9 o’clock position, the vehicle might have a bad idler arm.
What Causes an Idler Arm’s Ball Joint to Fail?
The ball joint has a ball and socket joint. If it loses grease or the boot tears, water can leak inside and rust can wear out the socket, creating excessive play.
How to Diagnose a Bad Idler Arm
How to Diagnose a Bad Idler Arm
- Raise and Support the Vehicle
Raise and support the vehicle with a jack and jack stands
- Grab the Tire at the 3 and 9 O’clock Position
With gloves, place your hands at the 3 and 9 o’clock position on the tire
- Test the Tire for Play
Wiggle the tire in and out and back and forth. Feel if the wheel shifts excessively and have an assistant observe the ball joint for excessive play
Fix a Bad Idler Arm Yourself
Learn how to fix a bad idler arm yourself with thousands of how-to videos in 1A Auto’s video library.
Shop Parts at 1aauto.com
Related Content
There are other reasons that your steering wheel may vibrate or shimmy while driving or braking. After running through your diagnosis of the idler arm, if you are no convinced the issue is there, try these other blogs to assist with your diagnosis.
- Bad Ball Joint? [Expert Advice to Diagnose & Fix]
- 3 Reasons Your Car Shakes When Accelerating
- Why Does My Steering Wheel Shake When I Drive?
- How to Diagnose a Bad Inner Tie Rod
- What to Do If Your Car Shakes When Braking
