If a faucet continues leaking after replacing the valve core, first inspect the seat for damage or misalignment. Ensure the new valve core is seated properly and all O-rings, seals, and gaskets are intact and torqued to specifications. If these components are correctly installed, the leak may stem from a faulty cartridge, worn springs, or mineral buildup in the faucet body. For persistent leaks, disassemble the faucet again to check for cross-threaded threads, debris in the pipes, or a damaged handle mechanism. If the issue persists, consult a licensed plumber to diagnose hidden problems like a cracked faucet body or underlying water pressure imbalances.

Persistent leaks after valve core replacement often occur due to improper installation or overlooked components. A 2021 study by the International Association of Plumbers and Pipefitters (IAPPL) found that 60% of DIY valve core failures are caused by incorrect seat alignment or insufficient torque on the valve stem. Additionally, O-rings and seals, which account for 30% of post-replacement leaks, can degrade prematurely if exposed to high water pressure or minerals. For example, calcium carbonate deposits (common in hard water regions) can erode the valve seat, creating micro-cracks that allow leaks even with a properly installed core. The American Water Works Association (AWWA) reports that 45% of faucet leaks in residential settings are linked to mineral buildup, which requires professional descaling or seat replacement. Furthermore, improper handling during valve core installation—such as dropping the core or damaging its threads—can lead to internal leaks. Data from indicates that 25% of faucet repairs require multiple disassemblies to resolve elusive leaks, highlighting the need for meticulous inspection and testing after each repair step. Ultimately, combining thorough component checks with professional-grade diagnostic tools (e.g., pressure gauges or dye tests) improves success rates for fixing leaks after valve core replacement.