First, see if the trademark logo is complete. The quality of the outer packaging of the product is good, the writing on the box is clear, and the overprint color is vivid. The packaging box and bag should be marked with the product name, specification model, quantity, registered trademark, factory name and telephone number, etc. Some manufacturers also put their own marks on the accessories. Some important components such as generators, distributors, fuel injection pumps, etc., are also equipped with instructions for use, certificates and inspectors to guide users in the proper use of maintenance. Care should be taken when purchasing, in case you buy fake and shoddy products.
Second, look at the geometric size with or without deformation. Some parts are subject to deformation due to improper manufacturing, transportation and storage. During inspection, the shaft parts can be rolled along the glass plate to see if there is any light leakage at the place where the parts are attached to the glass plate to judge whether it is bent. When the clutch plate or friction plate is purchased, the steel piece and friction can be used. The film is observed in front of the eyes to see if it is warped; when purchasing the oil seal, the oil seal end face with the skeleton should be rounded and can be attached to the flat glass without deflection; the outer edge of the non-frame oil seal should be straight and deformed by hand. After releasing the hand, it should be able to return to its original state. When purchasing all types of gaskets, you should also check the geometry and shape.
Third, see if the joint is flat. During the handling and storage of spare parts, due to vibration and bumping, burrs, indentations, breakage or cracks often occur at the joints, which affects the use of parts. Pay attention to check when purchasing.
Fourth, look at the surface of the parts with or without rust. The surface of qualified spare parts has both precision and bright finish. The more important the spare parts, the higher the precision, and the stricter the anti-rust and anti-corrosion of the packaging. Pay attention to the inspection when purchasing. If the parts are found to have rust spots, mildew spots or rubber cracks, loss of elasticity, or obvious turning pattern on the surface of the journal, it should be exchanged.
Fifth, see if the protective surface is intact. Most parts are factory coated with a protective layer. For example, the piston pin and the bearing bush are protected by paraffin; the surface of the piston ring and the cylinder sleeve is coated with anti-rust oil and wrapped with wrapping paper; the valve, piston and the like are immersed in anti-rust oil and then packaged in a plastic bag. If the seal is damaged, the paper is lost, the rust preventive oil or paraffin is lost during purchase, it should be returned.
Sixth, see if the glued parts are loose. An assembly made up of two or more parts, which are press-fitted, glued or welded between parts, and no looseness is allowed between them. For example, the oil pump plunger and the adjustment arm are combined by press-fitting; The clutch driven wheel and the steel piece are riveted and combined, the friction plate and the steel piece are riveted or glued; the paper filter element core frame and the filter paper are glued together; the wire head of the electrical equipment is welded. If it is found to be loose during purchase, it should be exchanged.
Seven, see if the rotating parts are flexible. When you purchase the rotating parts of the oil pump and other parts, turn the pump shaft by hand, you should feel flexible and no stuck; when purchasing the rolling bearing, support the inner ring of the bearing with one hand and the outer ring with the other hand, the outer ring should be able to rotate quickly and then, then Gradually stopped. If the rotating parts do not rotate, it indicates internal corrosion or deformation, so do not buy.
Eight, see if the assembly parts are missing. The formal assembly components are all in good condition to ensure smooth assembly and normal operation. If individual small parts on some assembly parts are missing, the assembly parts will not work or even be scrapped.