What Causes Noise During Cold Engine Start-Up?

[CassidyAnn]

The reasons for noise during cold engine start-up are: 1. Engine belt slippage; 2. Severe wear of the starter and flywheel; 3. Valve train malfunction; 4. Excessive clearance between hydraulic components and valves inside the engine cylinder head; 5. Timing chain failure; 6. Aging of the drive belt; 7. Three-way catalytic converter malfunction; 8. Engine temperature being too low. Precautions for cold start-up include: 1. Avoid prolonged idling to warm up the engine as components are not fully lubricated and the engine hasn't reached optimal operating temperature; 2. The fuel injector automatically increases fuel injection to raise RPM, normal driving can commence once the engine reaches proper operating temperature.