What is the tightening sequence for cylinder head bolts?
2 Answers
The tightening sequence for cylinder head bolts follows the principle of starting from the middle, then moving to both sides, and proceeding in a crisscross pattern. However, they should not be tightened all at once. The bolts should be tightened to the specified torque in at least three stages, with each stage involving slight loosening and re-tightening to prevent bending. This ensures the cylinder head remains flat and avoids damage to the cylinder gasket. Below is an explanation of the tightening sequence: 1. Due to the high sealing requirements of the cylinder head, following the principle of starting from the middle, then moving to both sides, and proceeding in a crisscross pattern prevents deformation caused by improper bolt installation and reduces the risk of punching. 2. Bolts are widely used detachable fasteners, typically used in conjunction with nuts. Because bolt connections are easy to install, remove, and reuse, they are very commonly used. The bolts on the engine cylinder head should not be overly tightened; they must be torqued according to specifications to avoid unnecessary issues.
I remember when I used to repair engines myself, the sequence for handling cylinder head bolts was crucial. Typically, you start from the center and tighten them step by step in a diagonal pattern outward, just like drawing from the center outward. You can't tighten them randomly, or the cylinder head will bear uneven force, leading to oil leaks or blown head gaskets, and the engine might overheat and fail. Once, I didn't follow the sequence, and the car started leaking coolant after just a few hundred kilometers, costing me more money for repairs. Now, I always do it in several steps: first, lightly pre-tighten all bolts to half the recommended torque with a wrench, then go back and slowly tighten them from the center diagonally to the specified torque. The manual usually has diagrams, so I recommend checking your vehicle's service manual, as the sequence may vary slightly for different engines. In short, the correct sequence ensures a flat, even seal and protects the engine's lifespan—don't skip this step.
