How to properly disassemble the cylinder head?

Nov. 11, 2019

In auto repair operations, some faults require disassembly of the cylinder head, such as engine overhaul, medium repair, cylinder head ablation, and removal of carbon deposits on the top of the piston. The disassembly and assembly of the cylinder head is a labor-intensive and technically demanding maintenance operation. If the operation cannot be carried out in accordance with technical standards, it is easy to cause ablation, leakage or water leakage of the cylinder head gasket. Let hyundai cylinder head factory talk about the technical requirements and operation precautions for disassembling the cylinder head.

First, the cylinder head removal

For most models, the removal of the cylinder head can be carried out on the vehicle. The engine compartment of a small number of models is too compact, and the engine assembly needs to be removed from the vehicle before the cylinder head can be removed. During the disassembly process, you need to pay attention to the following items:

1. Remove all piping and wiring connected to the cylinder head and mark them as necessary to prevent confusion;

2. After the engine is naturally cooled, drain the coolant;

3. For the engine with overhead camshaft, when disassembling the camshaft, loosen the camshaft fixing screw in the order of “from the sides to the middle” to prevent the camshaft from being bent and deformed;

4. When disassembling the cylinder head bolts, it must be carried out after the engine is completely cooled. When disassembling, follow the principle of “smoothly loosening from the two sides to the middle diagonal direction” to prevent the cylinder head from being warped and deformed;

5. Remove the old cylinder head gasket and clean the casting cylinder head and cylinder block sealing surface. This work requires special patience and carefulness. Thoroughly remove the old sealant, carbon deposits and corrosion products at the joint between the cylinder head and the cylinder block, and blow it off with compressed air.

6. Check the cylinder head and cylinder block sealing surface for deformation. Check with the ruler and the thickness gauge along the longitudinal and transverse directions of the sealing surface. Generally, the degree of irregularity on the sealing surface of the cylinder block and the cylinder head is not more than 0.10 mm, and the unevenness is not more than 0.03 mm in any 100 mm length. There must be no raised or recessed parts on the sealing surface. Check that the upper end of the cylinder liner is higher than the upper plane of the cylinder block, within the specified range (usually 0.05~0.15mm);

Cylinder Head

Cylinder Head

Second, the cylinder gasket installation

The cylinder head gasket is used to ensure the seal between the cylinder block and the cylinder head joint surface to prevent air leakage, water leakage and oil leakage. It is the most important kind of gasket on the car. It is heat-resistant, corrosion-resistant, has sufficient strength, certain elasticity and thermal conductivity, and ensures a reliable seal of the casting cylinder head for cars.

When installing the cylinder head gasket, pay attention to the installation direction. The basic principle is that the crimping edge faces the easy-to-trimming contact surface or hard surface. The specific description is as follows: If the cylinder head itself has the installation mark, install it according to the installation mark; if there is no installation mark, for the cast iron cylinder head, the curling side faces the cylinder head, and for the cast aluminum cylinder head, the curling side faces the cylinder body, when the cylinder When the cover cylinder is cast aluminum, the bead is directed toward the convex edge of the wet cylinder liner.