The wet-end seal stack for the GP5142 — from the crosshead pin through the plunger bore seals. This group contains the highest-frequency wear parts in the pump: O-rings, grooved ring, pressure ring, V-sleeve, sleeve support ring, seal sleeve, tension spring, oil scraper, and radial shaft seal, along with the structural plunger pipe, centering sleeve, tensioning screw, and copper ring.

These are the parts that go into a plunger repack. Dropping pressure under load without obvious valve damage almost always traces back to a worn plunger seal stack. The GP5142 Packing Plunger Kit covers the full repack in a single order — source individual components here when only part of the seal stack needs replacing.

For valve-related pressure loss, see GP5142 Valve Assembly Parts. Most seal components in this group are shared with the GP5132.