Kit Contents:
- 1 Drive Gear Assembly – PA350C
- 1 Idler Gear Assembly – PA351C
- 4 Roller Bearings – PM038
- 4 High Pressure Seals – PM036
- 4 Low Pressure Seals – PM037
- 5 Center Case Gaskets – PM007G01 / PM007G02
- 4 O-Rings – PB43
Why Rebuild Instead of Replace?
NAPCO 3" pumps are built for field serviceability. A PK300C rebuild kit restores the PA300C to factory performance at a fraction of replacement cost. No need to disconnect from piping — the center case can be accessed and serviced on-site with standard tools. The 3" platform handles high-capacity applications, and rebuilding preserves the investment in installation, piping, and motor coupling. Typical rebuild time is 3–5 hours. For a detailed economic analysis, see our pump rebuild vs. replacement guide.
When to Rebuild
- Reduced flow output — the PA300C delivers up to 158 GPM at 280 RPM; significant drops indicate worn internals
- Increased vibration or unusual noise, especially at higher pressures
- Visible fluid leakage past seals at the shaft or case joints
- Higher motor amperage draw for the same flow and pressure conditions
- Declining output during routine delivery operations
What's Inside the Kit
The drive and idler gear assemblies (PA350C/PA351C) are factory-matched — always replace both gears together for proper mesh clearance. Four roller bearings (PM038) support both shafts. High-pressure seals (PM036) and low-pressure seals (PM037) prevent leakage at operating pressures up to 100 PSI. Center case gaskets (PM007G01/PM007G02) and O-rings (PB43) seal the case halves. Total kit weight is 34 lb.
Ductile Iron vs. Stainless Steel
The PK300C uses ductile iron gears, ideal for petroleum, fuel transfer, adhesives, mining, asphalt, and general industrial fluids. Ductile iron provides excellent wear resistance and mechanical strength. For mining and explosives applications in particular, see our mining & explosives application guide. For corrosive chemicals, food-grade applications, or environments requiring stainless steel, use the PK300S instead. Both kits share identical bearings, seals, and gaskets — only the gear assemblies differ.
Related Resources
Compatible Pump:
PA300C – 3″ Ductile Iron Pump →Alternative Material:
PK300S – 3″ Stainless Steel Kit →Resources:
Field Maintenance Guide →Repair Procedures →