The basic common sense to extend the service life of engine valve mechanism

Gas distribution mechanism as an important part of the engine, the service life of the engine and whole life should be consistent, but in the use of often found in valve life is far below the whole life of engine, especially the valve, valve seat, valve guides and other major parts of short life, often in the two or three level maintenance, some parts have been more than limit the use and require early replacement, resulting in a tremendous waste of. This article on the superficial and prolong the service life of valve mechanism of.

The main reason, gas distribution mechanism of early damage
1.Repair of poor quality in the repair work is the problem of valve and valve seat surface machining quality is not up to the requirements, resulting in the work surface ablation, depression and early damage; camshaft bearing a scrape its clearance, contact area, each bearing concentric degree is not up to the requirements, the accelerated wear, the abnormal sound caused by early damage; valve guide in replacement parts, the reaming quality not up to the requirements, directly affect the service life of the valve and valve seat.
2.Repair data improper application: repair cannot scientifically choose the repair parts data are important reasons of early damage. If the valve and the valve seat contact width, provisions for 1~2.2mm inlet valve, exhaust valve for 1.5~2.5mm. But in the repair, people tend to think a bit wider than the narrow point of insurance, used to choose upper or close to the limit, the car valve face width and the newly repaired is approaching the limit. Another example of valve clearance, general motors for 0.2~0.25mm, but in the maintenance and adjustment also mistakenly believe that the gap is a bit bigger than a good point, therefore, the use of ultra limit. In fact, the gap is too large, not only reduces the power of the engine, but also the percussion sound (valve port since the early damage).

Matters needing attention in repair
Valve repair manual work in more technical differences due to maintenance personnel and cognitive bias , maintenance quality is difficult to meet the requirements ; therefore should be particularly emphasized in the maintenance of gas distribution sector service quality, and to take effective measures to improve the quality of maintenance to prolong its life.
1.Valve polishing: in repair operations, such as valve ablation, pits and depressions, all should be light grinding (serious when need replacing valve). Usually in the valve grinder, operations should pay attention to four issues: one is to ensure that the valve head and the rod of concentric, otherwise should first straightening; two is to grind the premise of complete cone as small as possible light grinding capacity; the three is to improve the surface finish; four is the valve end depression should be removed.
2.Valve seat reaming : valve seat reaming is usually manual labor , should pay special attention to three issues : First, eliminate depression , spots, could hinge on the basis of a complete cone , reaming amount as small as possible ; Second, even when forced to reaming , closing knife from the knife lighter , less hinge to observe in order to ensure reaming less volume and higher finish ; three are equipped with valve test to determine the location and width of a good face . Position should be adjusted to the lower part of the valve cone , partial or biased available under the upper and lower mouth reamer to adjust. Working width , the intake valve can be controlled by 0.9mm ( defined as 1 ~ 2.2mm), the exhaust valve can be controlled by 1.4mm ( defined as 1.5 ~ 2.5mm). Practice has proved that the width of the valve and valve seat grinding , the intake valve up to 1mm, the exhaust valve up to 1.5mm, were lower in the predetermined width , can greatly improve the service life.

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