No.1: Lubricant is only added and not changed
Many robots will pay attention to check the amount of lubricating oil and add it according to the standard, but they ignore the quality inspection of the lubricating oil and the replacement of the deteriorated oil, resulting in the moving parts of some engines always in poor lubrication Operation, thereby accelerating the wear of various parts.
No.2: Random use of butter
Butter is a commonly used grease in the repair of construction machinery, which can play a role of lubrication and sealing. Therefore, some repairmen will apply a layer of butter to the cylinder gasket when installing the cylinder gasket, which is believed to increase the tightness of the diesel engine. As everyone knows, this will actually affect the working performance of the diesel engine.
No.3: new cylinder liners and pistons are installed without option,
When replacing cylinder liners and pistons, the new cylinder liners and pistons are considered standard parts and are interchangeable, so they can be used after being installed. In fact, the sizes of the cylinder liner and the piston have a certain tolerance range. For example, if the cylinder liner of the largest size is matched with the piston of the smallest size, the fit clearance will be too large, resulting in weak compression and difficulty in starting.
No.4: Cylinder gap measurement is not accurate
When measuring the cylinder clearance, the piston skirt was not measured in a direction perpendicular to the piston pin hole, and was measured in other directions. The structural characteristics of the aluminum alloy piston are that the upper part is smaller and the lower part is a cone, and the cross section of the skirt is oval, so the cylinder gaps in the circumferential direction are not equal.
No.5: Piston flame heating
Because the piston and the piston pin are in an interference fit, when installing the piston pin, the piston should be heated to expand first. At this time, some maintenance personnel will directly place the piston on an open flame to heat it. When installing the piston pin, the piston can be evenly heated in hot oil to make it expand slowly. Do not directly heat it with an open flame.
No.6: Polishing the bearing pad with emery cloth
When someone replaces the bearing bush, in order to increase the contact area between the bearing bush and the crankshaft, they use abrasive cloth to replace the scraper bushing. This method is extremely undesirable in actual maintenance, because the abrasive particles on the abrasive cloth are harder, but the bearing alloy is softer. In this way, the abrasive particles are easily embedded in the alloy during grinding, and the journal wear will be accelerated when the diesel engine is working. Reduce the life of the crankshaft.
No.7: The bolt is too tight
During the disassembly process, bolts in many parts have required torque requirements, such as transmission boxes, cylinder heads, hubs, connecting rods, and front axles. The tightening torques are specified in the instructions and must not be changed at will. . However, many users mistakenly believe that it is safer to tighten tightly, but tightening too tightly may cause the screws or bolts to break, and may also cause failure due to threaded sliding buckles.
No.8: Add cold water to the water tank
Engine overload operation, poor heat dissipation, or lack of water in the water tank will cause the water tank to open. At this time, if cold water is added immediately, the cylinder head and cylinder body will burst. Therefore, once the water tank is found to be in use during the use, emergency measures should be taken to stop the operation to cool the cooling water of the diesel engine by itself.