Cylinder Head explained

Question

The cylinder head is a critical part of an internal combustion engine. It sits on top of the engine block and seals the top of the cylinders, forming the combustion chamber.

Function of a Cylinder Head

1. Seals the Cylinders

   • Bolted onto the engine block with a head gasket in between, preventing leaks of coolant, oil, and combustion gases.

2. Houses Valves & Camshaft (in some engines)

   • Contains intake valves (for air/fuel mixture) and exhaust valves (for burnt gases).

   • In OHC engines, the camshaft(s) also sit in the head to operate the valves.

3. Passages for Cooling & Lubrication

   • Channels for coolant (to prevent overheating) and oil (to lubricate valves, cams, etc.).

4. Spark or Fuel Injection

   • For petrol engines → spark plugs are fitted into the head.

   • For diesel engines (like the 300Tdi) → injectors are mounted in the head to spray fuel directly into the cylinders.

Symptoms of Cylinder Head Problems

• Head gasket failure → white smoke, oil in coolant, overheating.

• Warped head (from overheating) → loss of compression.

• Cracks → coolant or oil leaks, misfires.

Simple Visualization

[ Cylinder Head ]
   |   contains valves, injectors, spark plugs (or glow plugs for diesel engine)
   ↓
[ Head Gasket ]
   |   seals combustion & fluids
   ↓
[ Engine Block with Cylinders ]
   |   pistons move up & down