1.Before connecting the bolt, make sure that the bolt matches the pitch, tooth shape, rotation direction and other parameters of the nut.

2.Before fastening, thoroughly clean the sludge, carbon deposition, coolant or oil and other sundries and liquids in the bolt hole, and check whether the thread is in good condition and 3.whether the bolt is elongated.
When tightening bolts, tighten them according to the torque specified in the operating instructions. When not specified, determine the fastening torque reasonably according to the diameter of the bolts.
4. When removing the cylinder head bolts, it must wait until the engine is completely cooled, and the principle of "evenly loosening diagonally from both sides to the middle" should be followed to prevent the cylinder head from warping.
5. When the same part is fastened with multiple bolts, it should be tightened step by step in a certain order according to the shape of the connected part and the distribution of the bolts (generally 2-3 times). If there is a locating pin, it should start from the bolt close to the locating pin.
When tightening square or round group nuts, it must be done symmetrically.
When tightening rectangular group nuts, you should start from the middle and gradually expand symmetrically to both sides.