What Causes the Abnormal Noise When the Car Starts?
2 Answers
Issues that may cause squeaking noises when the car starts are as follows: 1. Check if the timing belt is broken or has frayed edges. 2. Inspect whether the starter is misaligned or if the belt connected to the starter is aged or curled. 3. Examine the idle motor. 4. Determine the noise within the cylinder block, which is likely related to the car's starting system. Methods to identify car noises are as follows: 1. Correctly distinguish between normal and abnormal noises: Normal vibration sounds from various system components, such as engine surface noise, gear impact sounds during gear shifts, intake and exhaust sounds from gas-operated sources, and gear meshing noises, are all considered normal. Abnormal noises can be categorized into minor, moderate, and severe based on their impact on car performance. Minor noises, such as sparking from high-voltage electricity leakage or slight looseness in rolling bearings, are generally low in volume, cause minimal wear on parts, and show no significant changes over a long period. Such issues can be tolerated without immediate repair. 2. Moderate noises, such as those from flywheel bearings or clutch release bearings, significantly affect car performance but can be temporarily tolerated. These noises are usually louder and indicate greater part wear, necessitating timely repairs. If such noises occur during driving, they can be temporarily ignored. Severe noises, such as loud sounds from crankshaft or connecting rod bearings accompanied by a drop in oil pressure, significant gear clashes in the transmission, or strong vibrations from the differential, severely impact the car and may cause or have already caused serious part damage. These issues require immediate attention, and the car should be stopped for inspection. Continuing to drive under such conditions can lead to major mechanical failures. 3. When diagnosing abnormal car noises, ensure good listening conditions and minimize interference from other noises to avoid misjudgment. It's helpful to amplify or reduce the noise intentionally—for example, using a screwdriver or other metal rod as a stethoscope to amplify the noise or employing single-cylinder cut-off to reduce it for better diagnosis. The diagnostic environment should be quiet, with minimal human interference.
When the car makes abnormal noises during startup, I feel the issue might come from several aspects. The most common is wear and tear of clutch-related components, such as when you press the clutch pedal and hear a gurgling sound, which is likely due to aging clutch plates or pressure plate issues. Another possibility is a problem with the suspension system, such as loose front suspension arms or ball joints, causing loud rattling noises when accelerating. If the engine mount is broken, engine vibrations during startup can lead to metallic clanging sounds. Issues with the drivetrain should not be ignored either, such as worn driveshaft or differential bearings. Additionally, if you recently changed tires or had maintenance done, improper installation might have left hidden risks. To pinpoint the exact cause, I recommend first identifying the specific location of the noise—whether it's from the front, rear, or underneath the car—to narrow down the troubleshooting scope. For a simple self-check, start the car in a safe area and gently press the accelerator to observe the frequency of the noise. Ignoring abnormal noises will only worsen the problem over time, affecting the vehicle's lifespan, so it's best to have a technician diagnose it early.
