The cylinder head bolts to the top of the engine block and caps off the cylinders. It houses the valves, spark plugs, and passages that let air and exhaust flow in and out.
Animated: how a Cylinder Head actually works
🔧 How It Works, Step by Step
1
Seal the cylinders
The head clamps down over the pistons to form the combustion chambers where fuel burns.
2
Route the airflow
Intake and exhaust ports in the head guide air-fuel into the cylinders and exhaust out.
3
Hold the valvetrain
The camshafts, valves, and springs mount in the head to control that airflow.
4
Carry coolant and oil
Internal passages route coolant to pull away heat and oil to lubricate the valvetrain.
🧩 The Key Parts
Combustion chamber
The shaped pocket above each piston where the air-fuel mix burns.
Valves and seats
Open and close to control airflow and seal the chamber.
Ports
Passages that carry intake air in and exhaust gases out.
Coolant passages
Channels that move coolant through the head to control temperature.
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The 50 most common check engine codes with likely cause and DIY fix cost. Sent once.
🩺 Signs of a Failing Cylinder Head
Overheating
White smoke or sweet smell from exhaust
Coolant loss with no visible leak
Milky oil on the dipstick
Misfire or rough running
⚠️ Common Problems
Cracked cylinder head
Overheating can crack the head, letting coolant into the cylinders or oil, causing smoke and misfires.
Warped head
Excess heat can warp the mating surface so the head gasket no longer seals, mixing coolant and combustion.
Valve seat or guide wear
Worn guides and seats let oil into the chamber and reduce compression, hurting power and burning oil.
💰 Cost to Fix
$1,000-$3,000typical range to repair or replace, parts and labor
❓ FAQ
What does the cylinder head do?
It seals the top of the cylinders and holds the valves, spark plugs, and airflow passages that make combustion possible.
Can a cracked cylinder head be repaired?
Sometimes a machine shop can weld or pin small cracks, but severe cracks usually mean replacing the head.
What causes a cylinder head to warp?
Overheating is the main cause, often from a coolant leak, failed thermostat, or bad water pump that lets the engine get too hot.