Here is an overview of the general knowledge of excavator engine maintenance. Different types of excavators are different for reference only.
1. At present, some cylinder gaskets are made of graphite, which have strong adhesion and good sealing, and can only be used once. When the graphite cylinder gasket is removed, the residual old cylinder gasket adhered to the plane of the engine body and cylinder head must be removed. Because the sundries adhered to the contact surface of the engine body and cylinder head are uneven, the cylinder gasket is not pressed tightly after the cylinder head is installed, so it can not bear the high temperature and The impact of high pressure gas is easy to damage the cylinder gasket again
2. The aluminum piston expands greatly when heated, and the piston pin shall be installed into the piston pin hole with a certain tightness at room temperature. During installation, the piston shall be heated to about 90 ℃ in oil or water in advance, and then take out the piston. When it is hot, the piston pin can be pushed into the piston pin hole smoothly by hand, and the assembly direction shall be noted
3. In order to ensure the tightness of the valve, when replacing the valve and valve seat, first cut it with a valve reamer with an appropriate angle, then apply the grinding paste between the valve and valve seat, and grind it with a valve grinder or manually until a neat and dark gray continuous ring belt with a width of 1 ~ 1.5mm is grinded. Method to test the tightness of the valve: clean the valve assembly and reinstall it on the cylinder head in situ, Pour gasoline into the inlet and exhaust passages respectively, and observe that there is no leakage at the joint of valve and valve seat after 1 ~ 2 minutes, which indicates that the sealing is good
4. The wear of crankshaft journal and bearing bush exceeds a certain range, which increases the gap. During work, due to the leakage of engine oil and the reduction of oil pressure, poor lubrication, aggravating the wear, and abnormal knocking sound. Repair method: remove the crankshaft and send it to the repair shop for grinding with crankshaft grinder, and then add thickened bearing bush with appropriate size to restore its original performance. For example, pad iron sheet or paper on the back of bearing bush, It can not reduce the clearance between the shaft and the bearing bush, but also deform the bearing bush and destroy the original clearance when the crankshaft is under pressure. Especially, paper padding can greatly reduce the heat transfer performance
5. After the diesel engine is started, the oil indicator rises, which not only indicates that the diesel engine is well lubricated, but also exposes the oil spray hole, so that the oil can be sprayed from the hole to lubricate the back shaking mechanism and make the diesel engine work normally. However, after some operators find that the oil indicator is damaged, they pull it out and throw it away and smash it into the peg. The peg will block the oil spray hole, the back shaking mechanism will not get oil lubrication and accelerate the wear of the parts
