New High Quality Diesel Injector 387-9430 387-9441 557-7627 20R-9079 20R-8066 For CAT C7

Appearance inspection
After taking out the new seal ring, first observe whether there are defects such as scratches, cracks, deformation or damage on its surface. These problems may cause the seal ring to fail to seal effectively and cause fuel leakage. Pay special attention to the edge of the seal ring to see if there are gaps or unevenness, because these places are easily squeezed during installation and affect the sealing performance.
Check whether the color of the seal ring is uniform and whether there is any discoloration or fading. If the seal ring is exposed to high temperature or chemical environment for a long time, it may cause its material to change and color to change, thus affecting its sealing performance.

Dimension inspection
Use calipers or other precise measuring tools to measure the inner diameter, outer diameter and thickness of the seal ring. Compare the measured values ​​with the standard dimensions specified by the vehicle manufacturer. Generally speaking, the dimensional deviation should be within the allowable tolerance range, usually between ±0.1mm and ±0.5mm, and the specific value varies depending on the vehicle model. If the size of the seal ring is out of tolerance, it may not be properly installed between the injector and the mounting seat and cannot provide a good seal.
Check whether the size of the seal ring matches the matching size of the injector and the mounting seat. For example, the inner diameter of the seal ring should be slightly smaller than the outer diameter of the injector so that it can fit tightly on the injector during installation; while the outer diameter of the seal ring should be slightly larger than the aperture of the mounting seat so that the seal ring can be compressed after installation to achieve a good seal.

Elasticity check
Press the seal ring gently with your fingers to observe its elasticity. A high-quality seal ring will quickly return to its original shape after being pressed, indicating that it has good elasticity. If the seal ring recovers slowly or cannot recover completely after being pressed, it means that its elasticity has decreased, which may be caused by aging or material problems. Such a seal ring may not provide sufficient sealing pressure after installation.
The seal ring can be gently stretched to observe its elastic limit. During the stretching process, the seal ring should be able to withstand a certain degree of deformation without breaking, and can return to its original shape after being released. If the seal ring is easy to break or cannot return to its original shape when stretched, it means that its elasticity is poor and is not suitable for use.

Hardness check
Generally, the hardness of the seal ring can be roughly judged by feel. Pinch the seal ring with your fingers to feel whether its hardness is moderate. If the seal is too hard, it may be difficult to compress during installation and cannot fit tightly with the injector and the mounting seat; if it is too soft, it may not provide sufficient sealing pressure, which may easily lead to fuel leakage. For some models with high sealing requirements, it may be necessary to use professional hardness testing instruments, such as the Shore hardness tester, to accurately measure the hardness of the seal to ensure that it meets the regulations of the vehicle manufacturer.
When checking the status of the seal, if any problem is found in any link, a new seal should be replaced in time to ensure the sealing performance of the injector after installation and avoid problems such as fuel leakage.