Why is there abnormal noise during cold start?

[DiAmir]

Reasons for abnormal noise after cold start: 1. Belt aging: The generator belt ages, and its rubber material is affected by thermal expansion and contraction. When the car is cold, the belt contracts, and daily rotation stretches the belt, which can easily cause the belt to slip during cold start, producing noise. 2. Valve tappet: Due to the valve tappet, during cold start, engine oil is pressurized from the oil pump into the engine oil passage before reaching the valve tappet, which can cause increased noise during cold start. 3. Loss of lubrication: The internal gears of the starter lose lubrication, causing sticking and affecting the timely return of the gears. 4. Carbon brush failure: The carbon brush inside the starter motor malfunctions.

[Martha]

I've been driving for over a decade, and it's common to hear strange noises when starting the car after it's been parked for a while in winter. The main reason is that the oil inside the engine thickens when the car is cold, flowing more slowly. Especially in the morning, when the oil hasn't fully pumped to the components, parts like pistons and bearing shells can grind directly, causing creaking sounds. Another common issue is the belt, such as the one for the alternator or air conditioning. If it's aged, loose, or covered in dust, it may squeak under the tension when the car starts. Carbon buildup can also cause trouble. If left uncleaned for a long time, deposits in the intake pipe can restrict airflow, making valve operation less smooth and increasing noise during acceleration. It's important to develop good habits: change the engine oil regularly and choose the right viscosity grade; check belt tension every six months and replace it if it's aged; don't neglect engine maintenance. Small issues left unattended can lead to bigger problems, like increased engine wear or even part failure, which can be costly and labor-intensive to repair. It's better to visit a professional shop early to avoid headaches.

[StTravis]

As a relatively new driver with just a few years of experience, I find cold-start noises quite annoying. Sometimes when I start my car for work in the morning, I hear squeaking or rattling sounds. After researching, I learned this isn't unusual. Experts explain that when a car sits idle for long periods, components cool down and oil thickens, causing metal parts to rub and produce strange noises. Alternatively, it could be loose or dirty belts - like a worn or deformed alternator belt that's prone to noise. More complex issues like timing chain wear can also amplify abnormal sounds during cold starts. I've found that minor cases can often be addressed with simple solutions, such as replacing belts or applying lubricants, but it's best to have professionals diagnose it with proper tools to avoid causing damage. Ignoring these noises long-term may worsen the problem, potentially leading to operational issues like sudden stalling or increased fuel consumption. When I hear noises while driving, I pull over to check for safety, and developing a habit of warming up the engine for a few minutes can help reduce the frequency of these sounds.

[OAngelina]

Such abnormal noises are commonly encountered in the workshop daily, with the core issue lying in cold-state operational differences. When the engine is just started, the low oil temperature and poor lubricant flowability cause friction sounds from bearings or cylinder walls; loose or wrinkled drive belt systems like water pump belts rubbing against pulley grooves produce sharp noises; components such as hydraulic lifters or timing systems develop increased clearances when cold, resulting in ticking sounds during startup. During troubleshooting, first identify the sound source location: front-end noises require checking belt tension, top-end noises indicate valve train wear, while bottom-end noises necessitate inspecting the oil pump condition. It is recommended to promptly switch to low-viscosity oil and replace belt components to prevent damage escalation. Persistent or worsening noises suggest underlying mechanical issues requiring professional diagnosis. Routine maintenance should focus on monitoring oil levels and belt lifespan to avoid costly repairs.

[OSebastian]

I enjoy fixing minor car issues myself, and cold start noises are mostly caused by poor engine lubrication or external drive problems. Thin, non-flowing oil inside the engine leads to metal-on-metal clanking; aged belts slipping due to looseness produce squealing; turbochargers or chains contracting in the cold create rattling. DIY checks include using a stethoscope to locate the noise source, a belt tension gauge to assess tightness, and the dipstick to check oil condition. Possible solutions involve switching to high-flow oil, adjusting belts, removing carbon deposits, or adding lubricants. Long-term neglect risks engine degradation and costly repairs, so saving money means regular DIY maintenance paired with timely professional inspections to prevent issues from escalating.