What are the causes of a blown cylinder head gasket?

[AniyahFitz]

Analysis of the causes of a blown cylinder head gasket is as follows: 1. Elongation or loosening of cylinder head bolts and nuts: Due to the extrusion deformation of the contact surface between the cylinder head and the engine block, the compression deformation of the cylinder head gasket, occasional overload caused by high-pressure gas on the cylinder head bolts and nuts, insufficient depth of cylinder head bolt threading, flattening of microscopic unevenness on the thread surface, and bolt necking caused by excessive torque, all can lead to elongation or loosening of cylinder head bolts and nuts. This results in insufficient and uneven pressure on the contact surface between the cylinder head and the engine block, allowing high-temperature and high-pressure gas to escape from areas with lower pressure, thereby burning out the cylinder head gasket. 2. Deformation of the contact surfaces of the cylinder head and engine block: If these contact surfaces are deformed, the cylinder head gasket cannot be evenly compressed, leading to gas leakage and subsequent burning of the gasket, which is also a major cause of cylinder head gasket failure. 3. Improper installation not meeting technical requirements: During installation, if the contact surface of the cylinder head gasket is not clean, the tightening sequence of cylinder head bolts and nuts is incorrect, the torque is insufficient or uneven, or the height of the upper end face of each cylinder liner above the engine block's upper plane is insufficient or unequal, gas leakage can occur, resulting in the burning of the cylinder head gasket. 4. Engine overheating: Abnormal operation of the engine cooling system, delayed fuel supply timing, and prolonged overload operation can all cause engine overheating. Particularly, the area between the intake and exhaust valve seats of the cylinder head and the outlet of the swirl chamber passage experiences higher temperatures. The high temperature causes the cylinder head gasket to lose its original elasticity and become brittle, eventually leading to burning. 5. Poor quality of the cylinder head gasket itself: Issues such as uneven thickness, uneven rolled edges, insufficient elasticity, inferior materials, uneven surfaces, or damage during disassembly and installation can easily lead to the burning of the cylinder head gasket.