Nov. 18, 2019
The following hyundai cylinder head factory will then talk to you about the technical requirements and operating precautions for the operation of disassembling the cylinder head.
Third, the installation of the cylinder head and the fastening method of the cylinder head bolt
The fastening of the cylinder head bolt is the most important part to ensure the quality of the cylinder head gasket. The specification of this operation directly affects the sealing quality of the cylinder head gasket. It must be operated in strict accordance with the technical standards. At the same time, some details must be Pay attention to:
1. Thoroughly clean the sludge, carbon deposit, coolant or oil in the bolt hole, and clean the thread with a tap if necessary, and blow it clean with compressed air;
2. Thoroughly clean the cylinder head bolts and carefully check the bolts. If there are cracks, pitting and necking, they should be scrapped and cannot be used any more. Use a caliper to measure the length of the bolt in the free state. If the plastic deformation of the bolt exceeds 1.5%, it cannot be used any more.
3. Before the installation, the casting cylinder head bolt should be coated with a little oil on the threaded part and the flange support surface to reduce the dry friction at the thread pair;
4. For the split type cylinder head, install the water distribution pipe and the intake pipe to the cylinder head (without gasket) before tightening the cylinder head bolt, and tighten according to the specified torque. Otherwise, the cylinder head side may not be a fault of water leakage or air leakage on the same plane;
5. Fasten the cylinder head bolts according to the technical specifications. The fastening methods and torques of different engine and cylinder head bolts are different. The general principle is: the crossover should be carried out symmetrically from the middle to the sides, and the torque will be tightened to the specified torque in 2 to 4 times. Repeat the tightening when the car is in use;
6. Due to the difference in material expansion coefficient, in order to prevent the expansion of the cylinder head bolts from being heated more than the expansion of the cast iron cylinder head, the compression degree is reduced. For the cast iron cylinder head, the second tightening is performed when the engine reaches the normal working temperature. Since the aluminum alloy cylinder head has a larger expansion coefficient than steel, the pressing force will be larger after the engine heats up, so it is only necessary to tighten once in the cold state.
7. Install the accessories, especially the timing structure. Be careful not to jump the teeth or the wrong teeth. The screws should be tightened symmetrically when the camshaft is installed.
In summary, in the operation of disassembling the aluminum cylinder head, it is necessary to patiently and carefully operate according to the technical standards. In particular, the cylinder head bolts should be tightened in strict accordance with the order specified by the engine manufacturer, the tightening torque and the tightening method. Only in this way can the cylinder be sealed with high quality.