What's the problem with the hot car not ringing and the cold car creaking?

The abnormal noise of the cold car creaks when the hot car doesn't ring. What is the problem of creaking when the cold car starts? It doesn't ring when it's hot because the solenoid valve installed between the carbon canister and the intake manifold opens after the cold car starts the engine. This is a normal phenomenon. The gasoline vapor adsorbed by the carbon canister is brought into the cylinder by air under the vacuum degree of the intake manifold to participate in combustion, which can reduce automobile exhaust emissions. Causes of abnormal noise during cold start:

1, due to low oil pressure or wear of the hydraulic tappet itself, air enters the hydraulic tappet, resulting in abnormal sound;

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

3. The continuous accumulation of sludge and carbon deposits leads to unclean throttle.

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