Symptoms of a cracked cylinder head are identical to those of a blown head gasket and include engine misfires, leaking oil that drains from the engine and the seemingly unexplained presence of coolant fluid in engine oil. Cracks in a vehicle's cylinder head may be large enough to see or may be invisible to the naked eye, and diagnosis of this issue as opposed to issues with similar symptoms, such as a blown head gasket, requires specific techniques including the use of dye and pressure to expose the cracks. Because it can be easily confused with other issues, diagnosing a cracked cylinder head requires more than simple knowledge of symptoms.
Cracking is a common problem for cylinder heads, and these cracks cause openings between different chambers in an engine. The exact nature of the damage to the cylinder head or head gasket will control the type of symptoms that show as a result of this damage, meaning that symptoms can vary. Cracks in cylinder heads can be fixed, or the cylinder head can simply be replaced if repair is not plausible. Thermal stress as a result of overheating or coolant loss is a leading cause of cracking cylinder heads; the cracks come about as a result of the natural expansion and contraction in metals.