Why New Mechanical Seals Leak Shortly After Installation?
Jun 10, 2026| Does a newly replaced mechanical seal leaking immediately mean the new part is defective? The impeller sits inside the pump casing, while the mechanical seal is fitted onto the shaft. External leakage usually occurs near the seal gland, not from the impeller.
A mechanical seal has two smooth mating sealing faces. A thin liquid film must exist between them - much like lubricant spread between two flat plates. This film both lubricates the faces and dissipates heat. If the seal chamber lacks liquid, or if the required flush fluid is cut off or blocked, the two faces will run dry and overheat, leading to leakage quickly.
Therefore, simply replacing the mechanical seal is not enough. You also need to check installation quality and pump operating conditions.