What is the disassembly and assembly sequence of engine cylinder head bolts?
2 Answers
Engine cylinder head bolt disassembly and assembly sequence: The disassembly sequence of cylinder head bolts is to remove them in a cross-symmetrical order from both sides to the center of the cylinder head in two to three steps; The installation sequence of cylinder head bolts is to tighten them in a cross pattern from the center to both sides in three to four steps according to the specified torque. The function of the cylinder head is to seal the cylinder, form the combustion chamber together with the piston, and withstand the effects of high-temperature and high-pressure gas. The cylinder head bears the mechanical load caused by gas force and the tightening of cylinder bolts, as well as high thermal load due to contact with high-temperature gas. To ensure good sealing of the cylinder, the cylinder head must neither be damaged nor deformed, so it should have sufficient strength and stiffness.
As someone who has worked on cars for years, I've seen many beginners forcefully remove cylinder head bolts, only to end up warping the head and creating a huge repair headache. The disassembly sequence is crucial—you generally start with the bolts at the center of the head, then work outward in a crisscross pattern, loosening or tightening gradually. This is the same as the star pattern mentioned in service manuals. Each step requires a torque wrench to ensure even pressure distribution—never rush haphazardly. Otherwise, leaking oil or air from the gasket would be the least of your worries; a ruined engine would really burn a hole in your wallet. I recommend checking your car's manual beforehand, as the exact sequence may vary slightly by model, especially for German cars, which are more particular. Don’t cut corners—take your time for reliability.
