Graco 455 ST Pro Pump (246426 / 17M873) – Complete Fluid Section Breakdown
The Graco 455 ST Pro pump, model 246426 (also known as 17M873), is a high-performance graco spray equipment component built to stand up to tough job-site demands. Designed as a direct replacement for older Nova, 395ST, 455ST, 495ST, STX, SPX, and FieldLazer models, this pump delivers consistent pressure, long-lasting seals, and full OEM reliability.
Why This OEM Pump Matters
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Built for durability: The Endurance-built lower pump assembly is crafted for high-pressure wear and tear.
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Easy field swaps: With its ProConnect design, this graco replacement pump installs quickly without special tools—making maintenance duties less painful for users on-site.
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Broader compatibility: It fits newer XT and Max units as well as older spray rigs—ideal when you’re working across brands and models.
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Consistent OEM quality: Every part is built to factory specifications, ensuring full backup support, warranty protection, and pressure-rated performance.
Ideal Applications
This fluid section is designed for heavy-duty use, ideal in:
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High-output contractor spray jobs
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Tough exterior coatings, textured finishes, and elastomeric application
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Demanding rental fleets and maintenance departments
Its adaptability across graco airless spray guns (Contractor PC, SG2/3, FTx, Magnum X5) makes it highly versatile for various projects.
Fluid Section: What You're Getting
This OEM pump is a complete fluid unit that includes:
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Pump housing and cylinder – All-metal fluid path to survive tough job-site use.
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Piston rod (Chromex) – Designed for extended wear and reduced corrosion.
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Valve assemblies & springs – Include inlet/outlet check valves with ball guides and springs.
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Seal packs – Factory rod and piston seals (Viton or EPDM), built to handle high pressure.
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ProConnect lower housing – Installs quickly with no tools required.
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Complete fluid section assembly – Replaces only what’s necessary to restore flow and pressure.
This package ensures you’ll replace only what’s worn and save time vs. rebuilding or troubleshooting via trial and error.
Installation & Maintenance Tips
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Swap with ease – Remove old fluid section, install the new 246426 pump, reconnect hoses, and you’re ready to spray again.
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Pick up related paint sprayer parts – OEM piston kits (243174 rod, 243181 valve), packing kits (18B260), and filters are recommended for long-lasting use.
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Prime and flush properly before starting your spray run. Keep hoses flowing freely to protect seals and reduce strain.
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Apply Throat Seal Liquid (TSL) after flush to maintain rod packings when idle.
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If issues arise, look into graco pump repair near me — many authorized service shops stock fluid sections and provide fast turnarounds.
Compatible Parts & Accessories
To ensure peak performance, consider adding these OEM components:
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Packing kits (18B260 / 244194) – Rod and intake rebuild over time.
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Piston Rod (243174) & Valve (243181) – Replacements in case of wear
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Manifold filters, suction tubes, hopper screens – Keep system debris-free
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TSL, guards, RACX tips – Supports XC apple and prevents overspray
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Magnum X5 parts compatibility – Guard kits, seals, and tips fit perfectly within this platform
Having these paint sprayer parts on-hand helps prevent job-site downtime.
Compatibility with Other Graco Products
This pump section shares parts and support with:
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STX / SPX lines, Nova Pro sprayers, FieldLazer striping units.
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Magnum X5 parts like guards, hoses, and tips — crossing over common thread sizes.
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XT / Max duplex systems — allowing you to maintain a diverse fleet with minimal spares.
When to Replace & Where to Get Help
Replace your fluid section pump when you notice:
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Loss of prime, pressure drop, or spitting
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Leaks around the housing or seals
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Reduced spray pattern quality or a shaky gun stroke
You can either install the graco replacement pump yourself or look for graco pump repair near me. Many service centers offer rebuilds or full replacements of the fluid section to quickly get you back to full production.
Final Takeaway
If you're running contractor-grade painting jobs, a clean and reliable fluid section is vital. The Graco 246426 pump (17M873) delivers:
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OEM-grade durability with Chromex rods and precision valve components
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Fast pump swaps with ProConnect lowers
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Full compatibility with your graco airless spray guns, graco magnum x5 parts, and varied graco spray equipment line
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Preventive maintenance support through TSL and pack kits
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Service network access via graco pump repair near me for expert rebuilds and diagnostics
Ready to Buy?
Visit SprayersAndParts.com for full exploded diagrams, OEM part lists, and same-day shipping. Plug in your part numbers, screenshots, or model info—they make it easy to find compatible paint sprayer parts, housings, and rebuild kits. Keep your pumps humming and your sprayer deployments smooth and stress-free.
With this guide, you’ll better understand your graco fluid section, its role in robust spraying, and how to keep it running at its best—all while stepping up your site efficiency and product longevity.