Is it normal for the engine to make abnormal noises when starting?
2 Answers
A normal engine should not produce any sharp noises during the startup process, and the idle sound should be uniform. When starting a cold engine, there might be a ticking sound, which diminishes and disappears as the engine warms up—this is considered normal. When gently pressing the accelerator to gradually increase the engine speed, the engine should run smoothly without any unusual noises. Rapidly pressing the accelerator pedal should result in a smooth increase in engine power without any hesitation or metallic knocking sounds. After driving the vehicle in a simulated mixed road condition for 5-10 minutes in an open area, the idle speed should remain stable without fluctuation, and the engine sound should be steady and uniform. Below are some reasons why a car engine might become louder: 1. The engine makes a ticking sound, similar to a pencil tapping on a table, and the sound increases with engine speed. Possible causes include contaminants inside the engine—recommend changing the oil and oil filter, and cleaning the engine. Other possibilities could be valve issues. 2. While driving, acceleration and ignition may seem normal, but if you notice the engine RPM is too high while maintaining a constant speed, yet the speed doesn’t increase accordingly. Check the coolant level, oil pressure (too high or too low), inspect the oil pressure gauge, or verify the ignition timing settings, as these could cause such symptoms. Other potential issues might involve internal engine problems, such as a clogged EGR valve. 3. The engine makes a tapping sound at idle, as if something is hitting metal. This sound might not be noticeable during acceleration or driving. Possible causes include cylinder valve issues—adjusting the valves may help. Low oil levels or insufficient oil pressure could also lead to similar problems, so check the engine oil pressure. 4. A whirring sound occurs during acceleration or deceleration, changing with RPM. Possible causes include low power steering fluid—top it up. Damaged alternator bearings, issues with the power steering pump, or water pump could also produce similar noises. 5. Pressing the accelerator pedal results in a popping sound from the exhaust, which might not be very loud. The car may drive normally, but fuel consumption could increase. Inspect the muffler and exhaust pipe for any damage.
If there is abnormal noise when starting the engine, it is indeed worth being vigilant, as I have encountered similar situations before. The abnormal noise may stem from several common issues, such as squeaking caused by aging or loose belts, rattling due to insufficient engine oil leading to increased internal friction, or continuous humming from worn-out alternator bearings. During daily driving, I usually perform a simple self-check first—verifying whether the oil level is adequate and if the belt tension is normal—because addressing these minor issues promptly can prevent bigger troubles. If the noise is more noticeable after a cold start, it may indicate that oil pressure hasn’t built up properly, requiring an inspection of the oil pump. It’s best not to delay for too long; otherwise, problems like piston rings or crankshaft bearings failing could cause severe engine damage, significantly increasing repair costs. Regular maintenance is the key to prevention. I typically follow the manual’s guidelines for oil and belt replacements to ensure smooth engine operation during startup and minimize the risk of unexpected breakdowns.
