What Causes the Engine to Be Particularly Loud When Starting?
2 Answers
An unusually loud engine during startup may be caused by carbon buildup in the engine. Over time, old engine oil becomes thinner, leading to increased carbon deposits. Thinner oil is more prone to oil blow-by, which exacerbates carbon buildup and results in significant power loss. When new oil is added, the engine may struggle to adapt to the oil's viscosity, potentially causing higher RPMs and increased engine noise. Regularly cleaning the vehicle's intake system at a 4S shop is the most effective way to minimize carbon buildup. It is recommended to perform this maintenance around every 30,000 kilometers. Adding Fuel System Cleaner: Directly adding a fuel system cleaner to the fuel tank is the simplest method, but its effects are temporary and not thorough. This approach is suitable for vehicles with lower mileage. Drip Cleaning: Drip cleaning can simultaneously remove carbon deposits and buildup from both the fuel system and the valves. This is a method commonly recommended by auto repair shops. Using a No-Dismantle Cleaning Machine: This method involves using a specialized no-dismantle cleaning machine to connect the engine's fuel inlet and return lines to the machine's corresponding lines, forming a closed loop with dedicated adapters.
My car makes a particularly loud noise when starting up. I've experienced this several times and have summarized the common causes. First is belt issues; for example, aging or loose fan belts or AC belts can cause squealing or roaring sounds during startup, which sound harsh. Second is insufficient or old engine oil; poor lubrication leads to increased engine friction, resulting in loud noise at startup and higher fuel consumption. Third is exhaust system failure; such as a damaged muffler or leaking pipes, which amplifies the exhaust sound, making it deep and loud. Fourth is valve system problems; improper valve clearance can increase noise, but this requires professional adjustment. Fifth is an aging starter motor; wear and tear on the motor can produce a harsh sound. Regularly check the belts for cracks when parked and try changing the oil. If the noise persists or worsens, don't delay—take it to a repair shop immediately to prevent small issues from turning into big problems.
