The cylinder head of a medium-speed four-stroke engine typically includes:

• 2 Inlet Valves for fresh air intake.
• 2 Exhaust Valves for expelling exhaust gases.
• 1 Fuel Injector for delivering fuel into the combustion chamber.
• Inlet and Exhaust Passages that direct the flow of air and exhaust gases.
• Cooling Spaces to ensure proper heat dissipation.

The cylinder head body is cast from pearlitic grey cast iron, which provides resistance to high combustion pressures and temperatures. The valves are seated on replaceable valve seats to facilitate maintenance.

Cracks in the cylinder head are typically caused by thermal fatigue due to poor cooling or intense local heating during the combustion process. Common areas prone to cracking include:

• The bridge area between the inlet and exhaust valves.
• The fuel injector pocket, where cracks may extend radially.
• The combustion chamber surface, due to intense heating and scale deposits reducing heat transfer.

• Compressive and Tensile stresses due to gas forces
• Thermal stresses due to excessive heat and improper cooling
• Overtightening of cylinder head bolts.
• Other factors: Very high peak pressures
• Casting defects.

By Design:

• Use materials such as pearlitic grey cast iron, which can withstand high stresses and temperatures.
• Ensure sufficient material thickness in areas subjected to high gas forces.
• Position the cylinder head securing studs close to the cylinder to reduce bending moments and support spans.
• Design adequate cooling spaces to ensure even heat dissipation.
• Thin material in heat transfer areas minimizes thermal gradients and stress.

By Maintenance:

• Maintain jacket cooling water to prevent scale deposition on heat transfer surfaces.
• Correctly tighten cylinder head bolts to avoid uneven stress distribution.
• Regularly maintain fuel equipment to prevent abnormal pressure peaks.