What Causes the Loud Noise When Starting a Car?

[HaydenRose]

During cold starts, the engine operates at a higher idle speed, which naturally produces more noise. Additionally, the sound from the secondary air pump compressing air contributes to the overall louder noise during ignition. Here are some common reasons for loud noises after starting a car: 1. Engine Oil. If the engine oil viscosity is too high, it can hinder proper engine operation, reduce lubrication effectiveness, and result in increased engine noise. 2. Belts. Check for any looseness in the belts. Loose belts can amplify the noise level in the engine compartment. 3. Coolant Temperature. Elevated engine noise may indicate that the coolant temperature is too high. 4. Idle Speed. Higher idle speeds typically lead to increased noise. Cleaning the throttle body, intake valves, and fuel injectors can help mitigate this issue.