Under the arrangement of the teacher, we disassembled the engine in a group of five people. Our group disassembled a four-cylinder in-line water-cooled engine. To disassemble and assemble, but we have disassembled and assembled the carburetor beforehand, so there is no special requirement here. Then remove external components such as the distributor, and remove components such as the motor and generator. Then remove the intake and exhaust pipes, remove the cylinder cover, and then remove the gasoline pump and thermostat on both sides, so that the external components of the engine are basically disassembled.
1. Then disassemble the body components according to the following requirements
1) Remove the fixing screws of the cylinder head 13. Note that the screws should be loosened crosswise from both ends to the middle, and the screws should be removed in three steps.
2) Lift off the cylinder head.
3) Take off the cylinder gasket, pay attention to the installation direction of the cylinder gasket.
4) Loosen the oil drain screw of the oil pan 20 to drain the oil in the oil pan.
5) Turn over the engine and remove the fixing screws of the oil pan (note that the screws should also be loosened from both ends toward the middle). Remove the oil pan and oil pan gasket.
6) Loosen the fixing screws of the primary oil filter, and remove the oil filter, oil pump sprocket and oil pump.
2. Disassemble the engine piston and connecting rod group
1) Turn the crankshaft so that the pistons of cylinders 1 and 4 of the engine are at the bottom dead center.
2) Remove the fastening nuts of the connecting rods of cylinders 1 and 4 respectively, remove the lower connecting rod bearing cap, pay attention to the matching marks of the connecting rods, and put them away in order.
3) Use a rubber hammer or a hammer wooden handle to push out the piston connecting rod assembly of cylinder 1 and cylinder 4 respectively, catch and take out the piston connecting rod assembly at the cylinder outlet by hand, and pay attention to the installation direction of the piston.
4) Put the connecting rod bearing cap, connecting rod bolts and nuts back in their original positions, and the connecting rods of different cylinders cannot be exchanged with each other.
5) Use the same method to disassemble the piston connecting rod groups of cylinders 2 and 3.
3. Remove the engine crankshaft and flywheel
1) Loosen the fastening screws of the flywheel and disassemble the flywheel. The flywheel is relatively heavy, so pay attention to safety when disassembling.
2) Remove the front and rear sealing flanges and oil seals of the crankshaft.
3) Loosen the fastening screws of the crankshaft main bearing cap from both ends to the middle as shown in the textbook, and pay attention to the assembly marks and orientation of the main bearing cap. The main bearing caps and bearing bushes of different cylinders cannot be exchanged.
4) Lift the crankshaft, put the main bearing cover and gasket back in place, and screw in the fixing screws a little. Pay attention to the positioning of the crankshaft thrust bearing and the installation direction of the opening.
4. Engine parts cleaning
1) Remove all the sludge and dirt from the engine parts, and scrape off the carbon deposits on the cylinder, cylinder head and piston.
2) Clean the engine parts in a special oil pool, especially the piston connecting rod assembly and crankshaft flywheel assembly.
5. Under the leadership of the teacher, we came to the multimedia classroom and watched the working process of the engine and the functions of each component. Through the teacher's explanation, we further understood the working principle of the engine.
5. Overall installation of the engine
1) Install all components in the reverse order of engine removal.
2) Installation precautions are as follows:
1. When installing the piston connecting rod assembly and the crankshaft flywheel assembly, special attention should be paid to the high cleanliness of the mating moving surfaces, and oil should be applied to the mating moving surfaces during assembly.
2. The matching parts cannot be exchanged with each other, and the installation direction should also be correct.
3. Each component should be tightened according to the specified torque and method, and tightened two to three times.
4. Before the piston connecting rod assembly is installed into the cylinder, the piston ring should be clamped with a special tool, and then the piston assembly should be pushed into the cylinder with a hammer wooden handle.
5. When installing the timing gear belt, care should be taken to align the position of the crankshaft timing belt pulley with the mark on the machine body and match the position of the camshaft timing belt pulley correctly.
