During the use of the automobile engine, due to the wear or loosening of some parts of the valve mechanism, it will lead to changes in the original valve clearance, so when generally traveling about 10,000 kilometers for maintenance, the valve clearance should be checked and adjusted to make it in line with
During the use of the automobile engine, due to the wear or loosening of some parts of the valve mechanism, it will lead to changes in the original valve clearance, so when generally traveling about 10,000 kilometers for maintenance, the valve clearance should be checked and adjusted to meet the technical specifications.
If the valve gap is too small, although the noise is small, the valve will be closed loosely due to the thermal expansion of the valve during operation, causing the valve and the valve seat to overheat and ablate. Especially for diesel engines, if the valve clearance is too small, it will also lead to insufficient cylinder compression pressure, thereby reducing the engine power, and it is difficult to start in serious cases (the diesel engine is ignited by compression). At the same time, too small valve clearance will also lead to incomplete combustion of combustible mixture, so that the HC content in exhaust emissions is significantly increased. The valve clearance is too large, the valve opens late and closes early, not only the working noise is large, but also the intake is insufficient and the exhaust is not clean, and the mixture continues to burn when the piston goes down, so that the engine (especially the exhaust manifold) overheats, reduces the engine power, and increases the fuel consumption.
Valve clearance check and adjustment methods There are two common valve clearance check and adjustment methods: one is cylinder-by-cylinder adjustment method, that is, according to the cylinder ignition order, determine the cylinder piston in the compression top dead center position, the cylinder inlet and exhaust valve clearance can be adjusted; After adjusting the crankshaft, gradually adjust the valve clearance of other cylinders according to this method. The second is the use of two adjustment method, that is, shake the crankshaft so that the first cylinder piston is at the top dead center of compression, and the flywheel mark is aligned with the inspection hole engraving line (such as EQ6100 engine).
At this time, the 1, 2, 4, 5, and 8, 9 valves can be adjusted (refers to the engine valve from front to back order); Then turn the crankshaft once, so that the six-cylinder piston is at the top dead center of the compression stroke, and adjust 3, 6, 7, 10 "plus two" (that is, 11, 12) valves, which is actually a memory adjustment. When adjusting, screw the adjustment screw, and pull back and forth between the valve rod end and the rocker arm with a thick gauge, feel that there is slight resistance, and then re-check until it is appropriate. The crankshaft needs to be shaken more times by cylinder method, which takes more time to check, but for the engine with more serious wear, the valve clearance is more accurate by cylinder method.
Two methods to adjust the valve clearance is more time and labor saving, but for different models need to remember different adjustable valve sequence numbers, complex models, maintenance personnel memory is somewhat difficult.
According to the specific requirements and regulations of automobile manufacturers for valve clearance adjustment. Adjustment should pay attention to the effect of temperature: valve rocker arm, valve rod temperature will have an impact on the valve clearance, generally speaking, the heat engine valve clearance adjustment should be smaller than the cooling machine requirements of the gap value, some cars require adjustment in the cooling machine, some cars in the hot and cold state can be adjusted, but the gap value is different.
Door clearance adjustment is one of the items that must be completed when maintaining the engine, and it is also an important operation content. Whether the adjustment is proper will directly affect the power and economy of the engine, and should be paid attention to by the driving repair personnel.