During car maintenance and repair, we often worry about accidentally buying fake and inferior parts and unsuitable parts. So, how can we buy qualified and suitable accessories? Eight things to pay attention to when purchasing auto parts: 1. Check whether the trademark logo is complete. The outer packaging of authentic products is of good quality, with clear writing on the box and bright overprinting colors. The packaging boxes and bags should be marked with the product name, specifications, model, quantity, registered trademark, factory name, address and phone 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 instruction manuals, certificates and inspector stamps to guide users in correct use and maintenance. You should be careful when purchasing to avoid buying fake and shoddy products. 2. Check whether the geometric dimensions are deformed. Some parts are prone to deformation due to improper manufacturing, transportation, and storage. During the inspection, you can roll the shaft part along the glass plate to see if there is light leakage at the joint between the part and the glass plate to determine whether it is bent; when purchasing the steel plate or friction plate of the clutch driven plate, you can roll the steel plate, Hold the friction plate in front of your eyes to see if it is warped; when purchasing an oil seal, the end face of the oil seal with a skeleton should be perfectly round and can fit the flat glass without deflection; the outer edge of the oil seal without a skeleton should be straight and can be used by hand. If it is deformed, it should return to its original shape after you let go. When purchasing various types of pads, you should also pay attention to checking the geometric size and shape. 3. Check whether the joint part is flat. During the transportation and storage of spare parts, due to vibration and bumps, burrs, indentations, damage or cracks often occur at the joint parts, which affects the use of the parts. Pay attention to inspection when purchasing. 4. Check whether there is any rust on the surface of the parts. The surface of qualified spare parts has both a certain degree of accuracy and a bright finish. The more important the spare parts, the higher the accuracy, and the stricter the rust and corrosion prevention of packaging. When purchasing, you should pay attention to inspection. If you find that the parts have rust spots, mildew spots, or the rubber parts are cracked or lose elasticity, or there are obvious turning tool lines on the journal surface, they should be replaced. 5. Check whether the protective surface is intact. Most parts are factory coated with a protective coating. For example, piston pins and bearing bushes are protected with paraffin; piston rings and cylinder liners are coated with anti-rust oil and wrapped in wrapping paper; valves, pistons, etc. are soaked in anti-rust oil and then sealed in plastic bags. If the sealing sleeve is damaged, the wrapping paper is missing, and the anti-rust oil or paraffin is lost when purchasing, it should be returned or replaced. 6. Check whether the glued parts are loose. Accessories composed of two or more parts, the parts are pressed, glued or welded, and no looseness is allowed between them. For example, the oil pump plunger and the adjusting arm are combined by press fitting; The clutch driven wheel and the steel plate are riveted together, the friction plate and the steel plate are riveted or glued; the paper filter core frame and the filter paper are glued together; the threads of the electrical equipment are welded. If any looseness is found when purchasing, it should be replaced. 7. Check whether the rotating parts are flexible. When purchasing rotating parts assemblies such as oil pumps, turn the pump shaft by hand and it should feel flexible and free of stagnation; when purchasing rolling bearings, support the inner ring of the bearing with one hand and rotate the outer ring with the other hand. The outer ring should be able to rotate quickly and freely, and then Gradually stop. If the rotating parts do not rotate properly, it means internal corrosion or damage.