What Causes Loud Engine Noise During Cold Start?
2 Answers
Loud engine noise during cold start can be caused by a cracked exhaust pipe, aged spark plugs, or damaged engine bearings. Below are detailed explanations for each of these issues: Cracked Exhaust Pipe: If the engine noise originates from the exhaust pipe, it indicates a crack in the exhaust pipe, which can be resolved by replacement. Aged Spark Plugs: If a screeching noise occurs during high-speed engine operation, it is likely due to aged spark plugs or clogging caused by dirt. Replacing them will solve the issue. Damaged Engine Bearings: If the engine noise changes with variations in maximum power RPM, it suggests damaged engine bearings, which can be fixed by replacement.
The engine noise is very loud during cold starts, a problem I used to encounter frequently. On winter mornings, the sound when starting the car was like metal grinding, very harsh. I believe the main reason is inadequate lubrication—the engine oil becomes thick at low temperatures and takes time to pump to various bearings and piston ring areas. If the oil level is low or too old, the lubrication effect worsens, leading to even louder noises. Another common issue is problems with the belt system, such as loose or cracked belts for the air conditioning or alternator, which produce squealing sounds during startup. Worn water pump bearings or a stuck tensioner pulley can also increase noise. I remember one time when my car's valve clearance wasn't adjusted properly, resulting in a large gap when cold and extremely loud noise. Whenever I hear such noises, I check the oil dipstick level and color to confirm if an oil change is needed. I recommend not delaying—visit a repair shop for a thorough inspection as soon as possible. Otherwise, prolonged operation under these conditions will increase engine wear and reduce its lifespan.
