Cylinder head bolts are fasteners used to secure the cylinder head to the engine block of an internal combustion engine. They are usually made of high-strength steel and are designed to withstand the high stress and heat generated by the engine.
1. If the bolts are manually tightened at one time, the pre-tightening force of the first tightened bolts will be greatly attenuated, and in some cases it will even become loose and fail, affecting the sealing of the cylinder head;
2. If tightening with a tightening machine, it is difficult for the bolts to reach at the same time, and the tightening force of the bolts that arrive first will drop more. Multiple tightenings usually begin with tightening to 50% of the specified torque. Usually, this torque can make the contact surface between the cylinder head bolts and the engine block close, and the interaction between the subsequent tightening bolts will be greatly reduced.
3. The cylinder head bolts of the diesel engine have a large number and a large diameter, generally 4? Eight bolts. This kind of multi-bolt fastener generally should be tightened according to the tightening sequence and tightening torque specified by the original factory;
4. If you don't know the original factory's regulations, you can tighten the tightening sequence evenly and symmetrically, from the inside to the outside, and from the middle to both ends, so as to ensure that the cylinder head can be leveled and pressed tightly. When tightening the bolts, it can be tightened according to the following procedures, that is, tighten to 1/3 of the specified torque value for the first time, tighten to 2/3 for the second time, and tighten to the specified value for the third time;
5. Then loosen the bolts to a completely loose state, tighten the bolts again to 1/2 of the specified value, and finally tighten to the specified value to complete the tightening cycle.