Kit Contents:
- 1 Drive Gear Assembly – PA350S
- 1 Idler Gear Assembly – PA351S
- 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 PK300S rebuild kit restores the PA300S to factory performance at a fraction of replacement cost. Stainless steel gears maintain corrosion resistance through multiple rebuild cycles. The center case can be accessed and serviced on-site with standard tools — no need to disconnect from piping. Typical rebuild time is 3–5 hours. See our cost analysis comparing rebuild vs. replacement for more details.
When to Rebuild
- Reduced flow output — the PA300S delivers up to 158 GPM at 280 RPM; significant drops indicate worn internals
- Increased vibration or unusual noise during operation
- Visible fluid leakage past seals at the shaft or case joints
- Higher motor amperage draw at the same flow and pressure
- Declining output during routine delivery operations
What's Inside the Kit
The drive and idler gear assemblies (PA350S/PA351S) are factory-matched stainless steel components — 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.
Stainless Steel Advantages
The PK300S stainless steel gears are required for corrosive chemicals, food-contact fluids, pharmaceutical ingredients, and applications where iron contamination is unacceptable. Stainless resists oxidation and pitting from acids, caustics, and chloride-containing solutions. The 3" platform provides high-capacity flow for large-volume chemical transfer operations. For food and beverage applications like syrups and oils, see our food processing pump guide. For non-corrosive applications like petroleum, adhesives, or mining, the PK300C ductile iron kit offers the same performance at lower material cost.
Related Resources
Compatible Pump:
PA300S – 3″ Stainless Steel Pump →Alternative Material:
PK300C – 3″ Ductile Iron Kit →Resources:
Field Maintenance Guide →Repair Procedures →