What Causes Engine Abnormal Noise During Cold Start?
2 Answers
Possible causes of engine abnormal noise during cold start include hydraulic lifters, valve clearance, dirty throttle body, carbon canister purge valve operation sound, and catalytic converter. Hydraulic lifters: Low oil pressure or wear in the hydraulic lifters themselves can cause air to enter the lifters, resulting in abnormal noise. Valve clearance: Wear of valve rocker arms leads to excessive valve clearance. Dirty throttle body: Accumulation of sludge and carbon deposits causes the throttle body to become dirty. Carbon canister purge valve operation sound: This is a normal sound and the vehicle can continue to be used. Catalytic converter: A "clicking" sound within half a minute after cold start that disappears afterward is typically caused by thermal expansion of the catalytic converter.
My car makes strange noises when starting cold, and there are quite a few possible reasons. For example, if the engine oil is too viscous at low temperatures and doesn't flow smoothly, it can lead to insufficient oil pressure and inadequate lubrication of components, resulting in a rattling sound. Additionally, if the belt has aged—such as a loose fan belt—it may produce a squealing noise during startup. Another issue could be with the hydraulic lifters; if oil can't enter them properly in a cold state, it creates a tapping sound. This is more common in winter because low temperatures cause metal to contract and deform. I've encountered this issue a few times, and the solution was to use the appropriate winter-grade oil or replace the belt. It's best to get it checked by a professional shop as soon as possible—delaying could lead to major engine repairs, wasting both time and money. Developing a habit of regular oil changes can help prevent such problems.
