Home > Faq

What should I pay attention to after disassembling and overhauling the diesel generator set and installing the main parts of the engine?

July 22, 2022
When the diesel generator set has some major failures, it is necessary to disassemble the set for overhaul, "overhaul" refers to the replacement of the four supporting parts of the generator set cylinder and shaft tiles, seals, grinding or replacement of deformed parts. After the repair, the unit needs to be reassembled, which is an important work, the quality of assembly will directly affect the reliability, economy and service life of the diesel generator set, how to smoothly install the parts into a complete diesel engine, there are high technical requirements, especially for the assembly of important components, we must pay attention to the following assembly points.
A, the installation of the cylinder liner
The working environment of the cylinder liner is very harsh, in the use of the process of faster wear, and combustion products on the cylinder is also corrosive, these will affect the engine performance, so the installation of the cylinder liner points to note: 1, will not be installed with a water barrier ring.
1, will not be installed in the block of the cylinder liner first into the block to try, to be able to flexible rotation and no obvious shaking as appropriate, while checking the cylinder liner step higher than the cylinder plane size is within the specified range.
2, regardless of the cylinder liner is new is old, in the installation of the cylinder liner are to use all new water resistance ring. The rubber of the water blocking ring should be soft, no cracks, specifications should be in line with the original engine requirements.
3, pressed into the cylinder liner, can be coated with some soapy water around the water blocking ring, for lubrication, cylinder body can also be properly coated with some, and then gently push the cylinder liner into the corresponding cylinder body hole according to the marked cylinder hole order number, to use special installation tools, slowly the cylinder liner completely pressed into the cylinder body, so that the shoulder and the cylinder stop on the plane of a close fit, do not allow the use of hand hammer force smash. After the installation with the bore percentage table measurement, the deformation of the water ring parts (size reduction and loss of round) shall not be greater than 0. 02 mm. deformation, should be pulled out of the cylinder liner repair water ring after reinstallation.
Second, the installation of the piston ring
Diesel generator piston ring is divided into gas and oil rings, they are installed in the piston ring groove, relying on elasticity on the cylinder wall, and with the piston up and down movement. Because the piston ring working environment is harsh, so it is also the diesel engine wear parts. When replacing the piston ring, the following points should be noted.
1, matching qualified piston ring, set in the piston should be used when the special piston ring pliers will be moderately open the piston ring, do not use excessive force.
2, assembly of piston rings, pay attention to the direction, the chrome-plated ring should be installed in the first ring groove, and the inner cut up; with the outer cut of the piston ring installation, the outer cut down; oil ring on the upper lip of the outer edge of the upper face are generally chamfered, while the lower lip of the lower face of the outer edge and no chamfer, should pay attention to the installation direction, can not be installed wrong.
3, the piston rod assembly into the cylinder before the need for the ring end gap position according to the piston circumferential direction evenly distributed, so as to avoid port overlap caused by air leakage, oil tampering and other phenomena. 
Third, the installation of the piston pin
In order to prevent the axial movement of the piston pin damage cylinder liner, piston pin seat hole at both ends of the retaining ring groove is equipped with spring retaining ring to fix the axial position of the piston pin. Piston pin installation using heating methods.
1, the piston in water or oil, evenly heated to 80 ~ 100 ℃, boil 5 ~ 10min. will be a piston pin retaining ring into the piston pin seat hole in the retaining ring groove.
2, the piston pin surface coated with lubricating oil, in the piston pin seat hole is not installed in the end of the spring by hand quickly pushed into the piston pin seat, through the connecting rod bushing, and make the piston top combustion chamber spade crater-shaped top and the oil hole in the small head of the connecting rod in the same direction, to ensure that the oil into the bushing, lubricating the bushing and piston pin. And then another retaining ring into the piston pin seat hole.
 Fourth, the installation of the piston connecting rod group
Piston connecting rod set of parts after repair, inspection, can be assembled into a combination. Before assembly should be thoroughly cleaned parts and the oil channels, and blow clean with compressed air. When assembling, pay attention to the following points.
1, the engine lock ring and piston pin ends should be left 0.10 ~ 0. 25 mm clearance; lock ring embedded in the depth of the groove, should be not less than 2/3 of the lock ring wire diameter. installation of pistons and connecting rods, should see the mark, the right direction.
2, the piston connecting rod group assembly, shall test the rod big head hole and the piston skirt centerline perpendicularity, its value shall not be less than 0.05 ~ 0. 08 mm
3, test the same engine piston connecting rod set components weight difference, the value shall not exceed the specified value.
4, in order to make the piston ring is easily installed into the cylinder, usually using special tools or a copper plate made of ring hoop wrapped around the piston ring, in the piston ring opening in a closed state to push into the cylinder.
5, assembly should check the piston, connecting rod cylinder number and forward mark, the piston ring up mark, piston pin and pin seat hole color grouping mark.
Fifth, the installation of the cylinder gasket
Cylinder gasket is pressed in the cylinder head bottom surface and the cylinder block between the upper surface, its function is to tightly close the combustion chamber, to prevent the escape of gas and cooling water infiltration. Cylinder gasket to work under high temperature, high pressure and uneven heating conditions, is one of the engine wear parts. The installation points of the cylinder gasket are as follows.
1, the cylinder gasket must be installed in a certain direction. To recognize the identification mark on the cylinder gasket, such as "up", "forward" or "this side up" mark map. If there is no mark on the surface, then the stamped out number mark towards the cylinder head.
2, when installing the cylinder head, check carefully whether the holes are correct, if the holes are offset, will damage the cylinder gasket and cause leakage of coolant. Do not apply sealant on the cylinder gasket to facilitate the next disassembly.
3, the cylinder head bolt length is different, be sure to bolt back to its original position respectively.
4, tighten the cylinder head bolts, should start from the center, according to the specified torque, the specified order in three times gradually tightened. After the new cylinder gasket pressure, then with the surface of the microscopic convexity and unevenness of the place to adapt. But repeatedly installed with the cylinder gasket, it is difficult to re-coincide with the original bump, which makes the cylinder gasket easy to early damage.
Six, the oil pump installation
When installing the oil pump, attention should be paid to the accurate meshing of the transmission gear and the driving gear on the camshaft, and the transmission shaft and the oil pump shaft should be kept in good coaxiality. In addition, the oil pump gear on the camshaft should be used to drive most models of engines in addition to the oil pump. When installing the oil pump, there exists a linkage between the distributor shaft and the camshaft and the oil pump.