What Causes Abnormal Noises from the Engine?
2 Answers
This phenomenon in the engine is related to the coolant, either due to insufficient coolant or issues with the quality of the replaced coolant. Such a condition after turning off the engine is normal, as some antifreeze returns to the expansion tank after shutdown, and the antifreeze temperature is relatively high, causing the tank to gurgle. How Automotive Coolant Works: Most automotive engines are water-cooled, relying on the continuous circulation of antifreeze within the engine for heat dissipation. Antifreeze follows two circulation paths inside the engine: a major cycle and a minor cycle. When the engine is first started, the antifreeze undergoes the minor cycle, bypassing the radiator for heat dissipation, which helps the engine warm up quickly. Once the engine reaches its normal operating temperature, the antifreeze switches to the major cycle, passing through the radiator to dissipate heat, thereby maintaining the engine within an appropriate operating temperature range. Other Types of Engine Abnormal Noises: A sharp belt squeal is usually caused by belt slippage. If there is a dry metal friction sound outside the engine while it is running, it typically indicates damage to the bearings of the generator, water pump, or power steering pump. A hissing sound during engine operation suggests a blockage in the exhaust system or a leak/break in the vacuum tube.
I've been driving for over 30 years, and I can always tell when there's trouble by the strange noises from the engine. The most common issues are loose or worn-out belts, which produce noticeable squeaking sounds during acceleration; insufficient engine oil is also frequent, causing increased internal friction and an annoying humming noise. I remember one time when the timing chain became loose—the clicking sound grew louder and louder, nearly causing a major accident. A hissing sound accompanied by exhaust fumes indicates a leak in the exhaust system, which is especially dangerous when overtaking. My advice to new drivers: regularly check the engine oil and belt tension, and if you hear any unusual noises, slow down and pull over immediately. Ignoring small problems can lead to major repairs—for example, a bad bearing can destroy the entire engine, costing thousands in replacement parts. Regular maintenance is key: change the oil every 5,000 kilometers, inspect the belts annually, and remember—prevention is better than regret.
