The engine is the core component of a machine and the main source of power. Many failures are caused by improper use and maintenance, so engine maintenance and repair are crucial. Learning to use and maintain the engine correctly can not only reduce the failure rate, but also extend its life, thereby creating more economic benefits. The following are 4 major precautions that should not be underestimated in diesel engine repair and maintenance.
4. Cooling
Daily inspection and maintenance of the cooling system.
Failure to use engine coolant or using incorrect coolant will cause the engine water jacket to rust and clog, engine temperature, power reduction, cylinder scuffing, cylinder liner cavitation and other faults, resulting in increased maintenance costs and reduced engine service life. Regular inspection and maintenance of the engine's cooling, lubrication, intake and exhaust, and fuel systems, and the use of high-quality engine maintenance products can extend the engine's service life and reduce maintenance costs.
Generally, C\L\Z series engines are required to use organic long-lasting coolant, and B\D series engines are recommended to use organic long-lasting coolant.
a. Check the expansion tank liquid.
b. Check the coolant level, check whether the water tank is blocked, and whether the pipeline has cracks, damage, or leakage;
c. Check the tension of the drive belt and whether the belt has cracks;
d. Visually check whether the cooling fan has cracks, loose rivets, bent or loose blades;
e. Check the fan and ensure it is firmly installed.
5. Rotating
1) Avoid long-term overload operation.
Some operators unilaterally pursue temporary economic benefits, causing the diesel engine to overload for a long time, resulting in early wear of the diesel engine parts. When the diesel engine speed remains unchanged and the load increases by 2 times, the diesel engine wear is also close to 2 times. If the diesel engine is overloaded for a long time, it will also cause the failure of burning the bearing and seizing the shaft.
2) Avoid long-term idling.
After the engine is started, it must run at idle speed for 3-5 minutes. After the oil pressure and coolant temperature rise, and all moving parts are fully lubricated, it can be accelerated. Before the engine stops, it must also run at idle speed for 3-5 minutes, using coolant and lubricating oil to take away the heat of the engine. After the temperature drops, it can be turned off. This point is especially important for engines equipped with exhaust gas turbochargers. It not only aggravates the wear of the engine, but also causes great damage to the turbocharger.
However, if the diesel engine idles for a long time, the injection pressure will decrease, which will cause poor diesel atomization. The condensed fuel in the combustion chamber or the unburned fuel vapor will flow into the oil pan along the cylinder wall, thereby reducing the viscosity of the engine oil and even causing it to deteriorate, which will destroy the lubricating effect of the engine oil, resulting in poor lubrication and aggravated wear of the diesel engine's moving parts, and may also cause the phenomenon of burning and pulling cylinders. At the same time, due to the low speed, when the diesel engine idles for a long time, the engine oil pressure is low, the engine oil circulation speed is reduced, and the cleaning ability is reduced, the sealing effect is poor, the heat transfer ability is reduced, the amount of lubricating oil received by the splash lubricated parts is reduced, and the wear and service life of the accelerated moving zero surface is reduced. For example: the wear between the piston, piston ring and cylinder wall increases; the wear of the transmission parts of the valve train increases: the life of the main bearing and connecting rod bearing is reduced, etc.
3) Avoid high-speed operation immediately after starting
After the diesel engine is cold started, the oil viscosity is high and the flow resistance is large, which makes the oil enter the friction pair with a time lag. The various parts of the diesel engine are not fully lubricated, causing the gears and bearings of the diesel engine to be damaged due to poor lubrication, and also aggravates the wear of the cylinder and bearing. In particular, supercharged diesel engines will cause the shaft of the turbocharger to burn. For this reason, the supercharged diesel engine should idle for a while after starting, and the speed can be increased after the oil temperature rises, the fluidity improves, and the supercharger is fully lubricated. This is even more important in the cold winter.
6. Missing
When repairing the engine, some small parts may be missed due to negligence. Some people even think that it doesn't matter whether they are installed or not. This is very dangerous. The following matters should be noted.
1) Valve lock plate
Valve lock plates should be installed in pairs. If they are missed or installed in reverse, the valve will be out of control and the piston and other parts will be damaged;
2) Anti-loosening device
The cotter pins, wires (lock plates) or spring washers on the connecting rod bolts and flywheel bolts are anti-loosening devices. Once missed, serious faults may occur during use;
3 )Piston pin lock ring
The piston pin lock ring is used to prevent the piston pin from moving. If missed, it will cause abnormal noise or damage the cylinder liner;
4) Oil nozzle
The oil nozzle used to lubricate the gears in the timing gear chamber of the engine. Once missed, it will cause serious oil leakage at this place, making the diesel engine oil pressure too low;
5) Tank cover and oil cap
If the water tank cap, oil filler cap, and fuel tank cap are lost, sand, dust, etc. will invade the cooling, lubrication, and fuel systems, which will aggravate the wear of various parts.
7. Milling
New diesel engines or overhauled diesel engines must be run-in.
After replacing cylinder liners, pistons, piston rings, bearings and other parts, new or overhauled diesel engines are not fully run-in and operated under load, which will cause early wear of parts, and some may also cause cylinder pulling and burning. Running-in is generally divided into the following two types.
1 Cold running-in
Remove the injector and use external force to drive the diesel engine to operate. At the same time, check the oil pressure and the temperature of each component. Pay attention to the sound of each component. After cold running-in, release the oil while the temperature is high, and clean the oil filter and oil channel.
2 Hot running-in
No-load hot running-in, pay attention to the working conditions of the diesel engine and the sounds of various parts, hot running-in according to the specified load and time, and often pay attention to the sounds of various parts and the blowby, exhaust, and oil return of the injector at the oil port. If problems are found, they should be eliminated in time.
