What is one common symptom of a blown head gasket?

A blown head gasket often leads to the mixing of coolant and engine oil, which is one of the most distinctive symptoms of this issue. The gasket serves as a seal between the engine block and the cylinder head, ensuring that engine oil or coolant does not mix. When it fails, it allows coolant to enter the oil passages, resulting in coolant contamination of the oil.

This can manifest as a milky or frothy substance on the oil dipstick or the oil filler cap, indicating the presence of coolant in the engine oil. This contamination disrupts the lubrication system, which can cause significant engine damage if not addressed promptly. Therefore, recognizing coolant in the oil as a symptom is vital for diagnosing a blown head gasket and mitigating further engine issues.