Cylinder Heads

What Cylinder Heads Do and Why They Matter

Big box stores and chains might be cheaper, but they can't guarantee the parts you're buying are genuine. Cylinder heads form the top section of your engine's combustion chambers where fuel ignites and power is generated. This component houses the valves, valve springs, camshafts, and related hardware that control the intake of air and fuel along with the expulsion of exhaust gases. Without a properly functioning cylinder head, your engine cannot produce power or run at all. The cylinder head also contains coolant passages that regulate engine temperature and prevent overheating during operation.

The Essential Work Cylinder Heads Perform

Cylinder heads seal the top of each cylinder bore in your engine block, creating enclosed spaces where combustion occurs. In your Nissan 370Z or Nissan NV200, the head contains precisely machined valve seats where intake and exhaust valves close to seal the combustion chamber during compression and power strokes. The head's internal passages direct fresh air-fuel mixture into cylinders and channel burned exhaust gases out through the exhaust ports. Coolant flows through drilled passages in the head, absorbing heat from combustion and preventing metal temperatures from exceeding safe limits. The combustion chamber shape machined into the head's lower surface controls compression ratio and influences how efficiently fuel burns. Genuine Nissan cylinder heads maintain exact specifications for port dimensions, valve angles, and chamber volumes that directly affect engine performance, while aftermarket heads often deviate from these critical measurements.

Understanding Why Cylinder Heads Fail

Cylinder heads crack and warp primarily due to overheating and thermal stress. When cooling systems fail or coolant levels drop too low, excessive heat causes the aluminum head material to expand unevenly, creating warped sealing surfaces that leak compression and allow coolant into combustion chambers. Repeated thermal cycles gradually fatigue the metal structure, eventually producing cracks that typically form between valve seats or extend into coolant passages. Detonation from low-octane fuel or faulty spark plugs creates shock waves that can crack combustion chambers. Improper installation torque on head bolts causes uneven clamping pressure that warps the head over time. Generic replacement heads frequently use inferior aluminum alloys with different thermal expansion characteristics that make them more susceptible to warping and cracking under normal operating conditions.

Knowing When Cylinder Head Replacement Becomes Necessary

Replace your cylinder head when white exhaust smoke indicates coolant burning in cylinders, or when compression testing reveals significant pressure loss. External coolant leaks at the head gasket surface combined with oil contamination in the cooling system point to head gasket failure often accompanied by head damage. Persistent engine overheating that continues after cooling system repairs suggests internal head cracks allowing combustion gases into coolant passages. Valve train noise that doesn't improve with adjustment may indicate worn cam bearing surfaces in the head requiring replacement.

For your next repair, rely on Cerritos Nissan's custom-made genuine components.