What is the cylinder head?

Nov. 07, 2019

The cylinder head is the cover of the engine and the components that close the cylinder, including the water jacket and the steam door and the cooling fins.

The cylinder head is cast from cast iron or aluminum alloy. It is the mounting base of the valve mechanism and the sealing cover of the cylinder. The cylinder and the top of the piston form the combustion chamber. Many have adopted a structure in which the camshaft support seat and the tappet guide hole seat are integrally molded with the cylinder head.

The cylinder head damage phenomenon is mostly the head deformation of the cylinder head and the cylinder hole sealing plane (the seal is damaged), the inlet and exhaust door seat holes are cracked, and the spark plug installation thread is damaged.

Structural function

1, Cylinder head working conditions and requirements

The cylinder head is subjected to mechanical forces and mechanical loads caused by tightening the cylinder head bolts, and is also subjected to high thermal loads due to contact with high temperature gas. In order to ensure a good seal of the cylinder, the cylinder head can neither be damaged nor deformed. For this purpose, the cylinder head should have sufficient strength and rigidity. In order to make the temperature distribution of the cylinder head as uniform as possible, to avoid thermal cracking between the inlet and exhaust valve seats, the cylinder head should be well cooled.

2, Cylinder head material

The cylinder heads are generally cast from high-quality gray cast iron or alloy cast iron, and the gasoline engines used in cars are mostly made of aluminum cylinder heads.

3, cylinder head construction

The cylinder head is a box-shaped part with complex structure. It is machined with inlet and exhaust valve seat holes, valve guide holes, spark plug mounting holes (gasoline engine) or injector mounting holes (diesel engine). A water jacket, an intake and exhaust passage, and a portion of the combustion chamber or combustion chamber are also cast in the cylinder head. If the camshaft is mounted on the cylinder head, the cylinder head is also machined with a cam bearing bore or cam bearing housing and its lubricating oil passage.

The cylinder head of the water-cooled engine has three structural forms: integral, block and single. In a multi-cylinder engine, if all cylinders share a cylinder head, the cylinder head is said to be a one-piece cylinder head; if every two cylinders have one cover or three cylinders and one cover, the cylinder head is a block type cylinder head; One cylinder is a one-piece cylinder head. Air-cooled engines are all unitary cylinder heads.

Cylinder Head

Cylinder Head


1. The casting cylinder head bolts should be evenly tightened and the oil supply time should be adjusted correctly.

2. Soft water should be added to the water tank and water should be changed as little as possible.

3. Diesel engines should avoid working under overload for a long time.

4. When the engine is working and the water tank is occasionally short of water, it should not be turned off immediately, but should be slowly added at low speed. Do not add cold water after the engine has gone hot. After parking, wait for the water temperature to drop below 40 °C before releasing the water. In the cold winter season, you can't add water immediately, but you should first heat the water and add water.

5. Check whether the cooling water holes are unblocked during assembly. Regularly clean the cooling system with an alkaline solution to remove scale oil in time.

The cylinder is an important part of the diesel engine. The wear of the cylinder should be minimized to help improve the performance and service life of the diesel engine.