What is the reason for the abnormal starting noise of the cold car?

If the cold start is a "click" sound, it may be caused by hydraulic tappets, valve clearance, dirty throttle, etc. If it is "clicking", it may be caused by three-way catalyst, timing parts, air conditioning belt and other reasons. If it is a "knock" sound, it may be a problem with the fuel tank exhaust valve or filter.

Causes of "click" sound during cold start:

1. Hydraulic tappet: Due to low oil pressure or wear of the hydraulic tappet itself, air enters the hydraulic tappet, resulting in "clicking" sound.

2. Valve clearance: The valve rocker arm is worn, resulting in excessive valve clearance.

3. Dirty throttle: Dirty throttle is caused by the continuous accumulation of sludge and carbon deposits.

4. Working sound of carbon canister solenoid valve: This is a normal sound and can be used continuously. If the noise is too loud, it is recommended to go to the 4S shop for inspection.

Causes of "click" sound during cold start:

1. Three-way catalytic converter: There is a "click" sound within half a minute after cold start, and then there is no sound, usually the sound generated by the thermal expansion of the three-way catalytic converter.

2. Timing part: There is a loud "click" sound during cold start, which is generally caused by wear, elongation and looseness of timing belt or chain. In addition, this sound is caused by the chain tensioner losing its tensioning function.

3. Naughty rubbing sound: If the prompt sound is turned on, the sound may be caused by air conditioning rubbing.

Causes of "knocking" in cold start;

1. The exhaust valve of the fuel tank is not working properly.

2. The fluid in the reflux pump is impacted.

3. The fuel filter is partially blocked.

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