In many cases, engine repair is unavoidable. Once a major engine failure occurs, it is necessary to carry out major engine disassembly repairs. An engine is a machine that can convert other forms of energy into mechanical energy, and is widely used in practical life. So today we will learn the detailed steps of engine repair and engine disassembly.

The process of engine repair and engine disassembly is as follows:

1. Remove the intake and exhaust pipes and the water outlet pipe of the cylinder head.

2. Remove the valve cover.

Remove the rocker arm shaft support retaining nut. Take out the rocker arm and shaft together. Remove all putters. And make a good order so that the original friction pair can be maintained during installation.

3. Remove the timing gear cover and gasket. Disassemble the camshaft.

Remove the timing belt upper guard. Loosen the camshaft timing pulley (hold the camshaft). Roll the crankshaft so that the cam uranium timing belt pulley is at the top dead center symbol of the first cylinder. The symbol on the camshaft timing belt pulley must be aligned with the symbol on the timing belt guard, roll the crankshaft to the top dead center of the first cylinder. Loosen the semi-automatic tensioner and remove the timing belt from the camshaft timing belt pulley. Remove the valve cover and then remove the camshaft timing pulley. Remove the half circle key from the camshaft. Remove the No. 1, 3, and 5 bearing caps first. Then replace and loosen the No. 2 and No. 4 bearing caps diagonally.

4. Remove the valve group, and when the valve is completely closed, remove the valve circlip and valve.

① Remove the side cover and gasket of the valve chamber, and check whether there are any marks on the top of the valve. Mark with a file on the top edge of the valve or on the valve stem).

② When the valve is closed. Use the valve spring pliers to compress the valve spring, use a screwdriver to remove the locking piece or use needle-nose pliers to remove the lock pin (do not use your hands), then loosen the valve spring pliers, and take out the valve, valve spring and spring seat .

5. Remove the cylinder head and cylinder head gasket.

When disassembling, it should be disassembled evenly from both ends to the center. Note: It is strictly forbidden to use a screwdriver to pry the cylinder head to prevent damage to the cylinder head and gasket.

When disassembling the cylinder head, use a hand hammer wooden handle to gently tap around the cylinder head to loosen it (the cylinder head bolts and nuts should be evenly disassembled from both ends to the center. It is not allowed to pry the cylinder head with a screwdriver to prevent damage to the cylinder head. liner). It is also possible to leave two loose bolts at both ends of the cylinder head, and remove all other cylinder head bolts. At this moment, hold the engine to roll the crankshaft, and the cylinder head gasket can be easily detached due to the effect of the air pressure in the cylinder. Cylinder exterior. Then remove the cylinder head and cylinder head gasket.

6. Raise the side of the engine with the valve upwards.

Check the clutch cover and flywheel for marks. If there is no mark, add the mark and remove the clutch fixing bolts symmetrically. Put the engine down on the bench, check whether there are any marks on the clutch cover and flywheel, if there are no marks, mark them, then remove the clutch fixing bolts symmetrically and evenly, and take off the clutch assembly.

7. Remove the oil pan and gasket, and remove some accessories of the oil pump together.

Remove the oil pan, gasket, and oil filter and oil pipe, together with the oil pump.

8. Roll the crankshaft in the most convenient position, and check the marks on the piston top and the big end of the connecting rod.

If there is no mark, mark the piston top and the big end of the connecting rod with metal objects in order. Remove the connecting rod bearing seat and gasket and put them in order. Using a hand mallet, remove the piston rod assembly from the upper part of the cylinder block. The connecting rod cover, connecting rod and gasket should be fixed as they are.

Check if there are any marks on the timing gears, if there are no marks, make corresponding marks on the two gears (when the first cylinder is at the top dead center position), and then remove the camshaft crankshaft, middle and rear journal bushing fixing bolts and bushing, and then pull out the camshaft smoothly; take out the valve lifter and lifter bracket.

9. Remove the starting claw and remove the locking piece. Use the puller to remove the pulley and change the shock absorber.

10. Check whether there is a symbol on the timing gear. If there is no mark, mark should be made at the two rounds of operation.

11. Put the engine upside down on the workbench and remove the main bearing.

Put the bearings in their respective covers in turn, remove the crankshaft, and put the bearings and pads back in place. and fix it.

First, pry off the lock piece on the fixing bolt of the crankshaft bearing seat or remove the lock wire (check whether there is a mark on the bearing cover. If there is no mark, mark it in order). Remove the fixing bolts, take off the bearing caps and gaskets and put them in order, lift off the crankshaft, put the bearing caps and gaskets back in their original positions, and tighten the fixing bolts a little.

12. Remove the crankshaft rear oil seal and flywheel housing.

Unscrew the flywheel fixing bolts and remove the flywheel from the crankshaft flange.

13. Differentiate the piston connecting rod group.

① Turn the connecting rod to be removed to the bottom dead center, and check whether there are marks on the top of the piston and the big end of the connecting rod. If there is no mark, mark the top of the piston and the big end of the connecting rod in order.

② Remove the connecting rod nuts, remove the connecting rod end caps, gaskets and bearings, and place them separately in order to avoid confusion.

③ Push the connecting rod by hand to separate the connecting rod from the journal. Push out the piston connecting rod group with a wooden handle with a hammer (if the cylinder port is ground into a step, it should be leveled first to avoid damage to the piston ring).

④ After taking out the piston connecting rod group, install the connecting rod end cover, gasket, stud and nut as they are to prevent disorder.

14. Remove the piston pin. After the engine is disassembled, it should be repaired according to the condition of the parts.

First check the mark on the top of the piston, then remove the snap ring (commonly known as the snap ring), use the piston pin to shoot out the piston pin, and put it in order (for aluminum piston, the piston should be heated in water to 75～ 85°C and then shoot out the piston pin).

15. After the engine is disassembled, the condition of the parts should be distinguished, cleaned, inspected and repaired.

The above is only the process of a single engine repair and engine disassembly, and the process of different models and engine structure differences may be different, so the method of the engine disassembly process is still based on the actual model situation. Please refer to it as appropriate!