What are the symptoms of a bad cylinder head gasket in a car?

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Symptoms of a bad cylinder head gasket in a car: 1. Engine cylinder head leakage: Damage to the cylinder head gasket can cause poor sealing between the cylinder head and the engine block, leading to gas leakage during operation, accompanied by splashing of oil and water, producing a sound of liquid mixed with gas splashing; 2. Reduced cylinder pressure: Poor sealing between the cylinder head and the engine block allows compressed gas in the cylinder to leak through the gaps, causing abnormal engine operation and shaking at idle; 3. Oil and coolant leakage: Damage to the engine gasket can result in coolant and oil leakage, which may mix together, leading to adverse reactions in the engine; 4. Gas entering oil or coolant passages: When high-pressure gas enters the oil or coolant passages, it can affect the lubrication of internal engine components to some extent, potentially causing increased internal engine temperature, severe component wear, and affecting the engine's normal operation.