When checking for abnormal noises in the car chassis, the first step is to determine whether the noise originates from the engine or the chassis. If the noise occurs only when the engine is running, it is generally an abnormal engine noise. However, if the noise persists when the car is moving with the engine off, in neutral gear, or with the clutch pedal depressed while coasting, it is likely coming from the chassis. Below are the possible causes of the noise: 1. Resonance-induced noise: Most often, this is caused by resonance between the engine guard plate and the chassis. Resonance in the chassis is usually easy to observe, as it does not occur continuously but rather within a specific engine RPM range. 2. Issues with the stabilizer bar bushings: Symptom: The chassis makes noise when driving over uneven roads. The stabilizer bar, also known as an anti-roll bar or sway bar, has two clamps that contain the bushings. Exposure to cold in winter, heat in summer, and contamination from dirt and dust can cause these bushings to harden over time. This affects the suspension's ability to compensate for uneven road surfaces, leading to a creaking sound when the wheels move at different heights. 3. Loose bolts causing noise: For example, loose bolts in components such as the control arm, linkage, or shock absorber. The reason is simple—parts that should be tightly fastened become loose, leading to movement and noise.
