A First, only replace the plunger and oil nozzle, ignoring the technical status of the oil valve. After the oil outlet valve is worn, the remaining pressure of the high-pressure oil pipe will be too high, resulting in the oil injection nozzle not simply and dripping oil, resulting in diesel exhaust smoke, cylinder knocking, and unstable operation. The method is to check the oil valve, with a measuring range of 0-600 kg/cm2 pressure gauge detection, the dial from 200 kg to 180 kg/cm2, the pressure holding time should be greater than 15 seconds, otherwise the oil valve should be replaced; Or the high pressure oil pipe mouth up, pump out diesel, so that the oil level and pipe mouth level, put the throttle back to the stop position, turn the wheel half a circle, the high pressure oil pipe mouth diesel non-suction is qualified, otherwise the oil valve should be replaced.
Second, only adjust the valve clearance, ignoring the valve timing. Most people only adjust the valve clearance according to the value specified in the manual, but ignore to check whether the valve phase is on time. Especially for the aging machine, due to the change of geometry after CAM wear, the valve opens late and closes early, which will lead to insufficient intake, unclean exhaust, increased fuel consumption and decreased power. Therefore, when adjusting the valve clearance of aged diesel engines, the valve clearance value should be reduced appropriately to compensate for the valve phase error. For example, the S195 diesel engine, the valve clearance is reduced by 0.1 mm, and the valve phase is changed by 3 degrees. However, the valve gap should not be less than 0.2 mm, otherwise it will be affected by expansion, which will cause the valve to close loosely. If the valve clearance is 0.2 mm, and the valve phase error is still more than 5 degrees, and the diesel engine working condition is significantly worse, the camshaft should be replaced.
Third, only look at the amount of oil in the oil pan, ignoring the quality of oil. Many people only supplement the engine oil, never check the quality of the oil, nor replace it. As everyone knows, the waste oil that should be replaced contains a large number of oxidizing substances and metal chips, which reduces the lubrication performance, aggravates the wear of the parts, and shortens its service life, so the oil quality in the machine should be checked at any time. The general method is to use the hand twist oil, if you feel mechanical impurities or viscosity is not enough, it should be replaced in time. Another way to check is to drop the used oil on the white paper, such as small black spots and light color.
Fourth, only know the maintenance of the air filter, ignoring the air short circuit. There are many reasons for air short circuit, such as the air filter fixed on the tricycle frame, the intake pipe is not welded properly, the intake pipe is not sealed gasket at the joint, the intake pipe is inserted into the hose loosely without clamping, the intake hose is broken undetected, and the air filter lacks rubber rings, which will cause air short circuit. Make the unfiltered air into the cylinder, aggravate the wear of the cylinder, piston, piston ring, valve and other parts.
Five, only clean the oil filter, ignoring the cleaning of the oil chamber. Most of the connecting rod journal of diesel engine is hollow, with oil plug at both ends, which is called purification chamber. Under the action of centrifugal force, the impurities of the oil lubricating the connecting rod bearing shell are attached to the cavity wall, thus improving the lubrication quality. General diesel engine every 500 hours to remove the oil plug.