Large exhaust smoke of excavator? Insufficient engine power? What went wrong? In theory, the large exhaust emission of the engine means that the fuel injected into the cylinder cannot be completely burned. At this time, if the power is not reduced, it may be that the oil supply set by the oil pump is too large. So what should we check the excavator?
Perform the following checks:
1. Air filter: when the air filter is too dirty, it will cause insufficient air intake. The serious smoke exhaust at this time must be accompanied by an alarm (when this device is available). The simple inspection method is to remove the air filter for commissioning.
2. Turbocharger: check the turbocharger when the engine operation is still not improved after removing the air filter. The standard method is to measure the air supply pressure of the turbocharger to the engine. In fact, most of them are to check the mechanical state of the turbocharger: that is to say, the turbocharger core is normal without radial and axial movement, flexible rotation and chamber sweeping.
3. Cylinder cutout: when the turbocharger is normal, the air intake fault can be eliminated. At this time, the cylinder cutout method can be used to determine the working condition of each cylinder. Set the engine speed at idle speed (or the lowest speed), disconnect the high-pressure oil pipe of each cylinder in turn with a spanner, and compare the engine sound after disconnecting the high-pressure oil pipe. When a cylinder disconnects the high-pressure oil pipe, the engine sound (here refers to the working sound of the engine, not the knocking sound caused by mechanical problems) does not change significantly, it can be considered that the cylinder does not work or works poorly. At this time, remove the corresponding fuel injector, connect the fuel injector outside the engine block, and then start the engine to observe the atomization of the fuel injector.
4. Lower exhaust: there is very small lower exhaust during normal operation of the engine. If the lower exhaust is obviously too large, the cylinder barrel, piston and piston ring may be seriously worn, or the piston ring may be aligned and broken. It will also cause large smoke exhaust and insufficient power. The engine with severe exhaust shall be disassembled for maintenance.
5. Cylinder pressure: cylinder pressure test is required for severe lower exhaust. Install the pressure gauge into the cylinder to be measured, and start the engine to measure the cylinder pressure of the cylinder. Various engines have different requirements for standard cylinder pressure, but they are all about 3Mpa (30kg/cm2). At the same time, the fuel injector can be installed reversely to observe the fuel spray. If the fuel injector is not atomized or the atomization is poor, it can be considered that the fuel injector has been damaged.
Check whether the valve clearance of the cylinder is within the standard range. If it is not, it needs to be adjusted. If it is within the standard range, it may be a valve problem, and the engine needs to be disassembled for inspection. Adjustment method of valve clearance (take 6-cylinder engine and firing sequence 1-5-3-6-2-4 as an example): turn the engine to the compression top dead center of cylinder 1 (exhaust of cylinder 6 ends and intake begins), and check the intake valves of cylinders 1, 2 and 4 and the exhaust valves of cylinders 1, 3 and 5 Then turn the engine to the top dead center of cylinder 6 (exhaust of cylinder 1 ends and intake begins), and check other valves.
7. Timing (oil supply time, oil supply advance angle, ignition time) the ignition time varies for different engines. Abnormal ignition time will cause insufficient engine power, high temperature, etc. the inspection method for the ignition time of diesel engine is as follows (take the 6-cylinder engine and ignition sequence 1-5-3-6-2-4 as an example): A. remove the high-pressure oil pipe of cylinder 1, remove the oil outlet valve spool and spring, and then press the oil outlet valve seat on the oil pump. B. I pressurize the hand pump and turn the engine at the same time When the oil outlet does not discharge oil, it is the starting position of oil supply. At this time, there is a scale value on the belt pulley (some engines are on the flywheel) corresponding to the pointer on the engine body. At this time, the scale value is the oil supply advance angle Compare with the standard value and adjust accordingly. The engine is the source of power for construction machinery equipment. Checking the engine will not only make the equipment more powerful, but also prolong the service life of the engine.
