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Clunking Noise Over Bumps - 2019 IS 300 F Sport

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Mike T. · rep 0 · May 25, 3:30 AM · 1 replies · solved · Question

Vehicle: 2019 Lexus IS 300 F Sport RWD

Hey everyone, I've got a growing concern with my 2019 Lexus IS 300 F Sport. For the past few weeks, I've been hearing a distinct clunking or knocking noise, especially when going over speed bumps or uneven pavement at low speeds. It seems to be coming from the front suspension, possibly on the passenger side.

The car has about 45,000 miles on it. I've checked for anything loose visually, but I'm not a mechanic. It's really starting to bother me and makes me worry about the car's handling and safety. Has anyone else experienced a similar issue with their IS 300, particularly the F Sport models with their stiffer suspension?

What are the common culprits for this type of noise? Is it something simple like sway bar links, or could it be something more serious like control arm bushings or even the struts themselves? Any advice on what to tell the mechanic or what to look for would be great!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:30 AM

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ClearTheCode admin answer:

A clunking or knocking noise from the front suspension, particularly over bumps, is a common indicator of worn or loose suspension components. For your 2019 Lexus IS 300 F Sport with 45,000 miles, several parts could be the culprit. The F Sport's stiffer suspension can sometimes make these noises more apparent or accelerate wear on certain components.

  1. Common Causes of Suspension Clunking:

    • Sway Bar End Links: These are a very common source of clunking noises. The ball joints on the end links can wear out, creating play that manifests as a clunk, especially when one side of the suspension moves independently of the other (like over a speed bump).
    • Control Arm Bushings: The rubber bushings in the control arms (upper and lower) can degrade or crack over time. When worn, they allow excessive movement, leading to metal-on-metal contact or just loose movement that causes a clunk.
    • Ball Joints: Similar to sway bar links, the ball joints in the control arms or steering knuckle can wear out, causing play and noise.
    • Strut Mounts/Bearings: The top mounts of the struts can wear out, or the bearing within them can fail, leading to clunking or popping noises, especially when turning or going over bumps.
    • Loose Components: Less common, but sometimes a loose bolt on a suspension component or even a loose caliper can cause similar sounds.

  2. Diagnostic Approach:

    • A qualified technician will typically lift the vehicle and perform a thorough inspection of all front suspension components. They will look for torn bushings, excessive play in ball joints, and any signs of wear or looseness.
    • They might also use a pry bar to check for play in various joints and bushings, or even listen with a stethoscope while the suspension is loaded or moved.

  3. Relevant OBD-II Codes:

    • Suspension noises typically do not trigger OBD-II diagnostic trouble codes, as they are mechanical issues not directly monitored by the engine or transmission control units.

When to See a Shop:

It's highly recommended to have your Lexus IS 300 inspected by a professional mechanic as soon as possible. While some clunks might seem minor, worn suspension components can affect your vehicle's handling, tire wear, and potentially compromise safety. Addressing the issue promptly can prevent further damage to other connected parts.

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