Graco 108528 Piston Nut
$223.50
In Stock
The Graco 108528 Piston Nut is an OEM replacement part used in specific Graco industrial pump lowers. It ensures secure connection of the piston rod for reliable operation under high pressure.
- Fits selected High-Flo 4-Ball pump lowers
- Compatible with President, Viscount / Viscount II, and NXT powered systems
- OEM-grade durability for long service life
Quantity
Genuine OEM Part
Fast Shipping (Order by 1 PM CST)
Easy Returns
About the OEM Graco 108528 Piston Nut
Compatible Machines / Pump Families
The Graco 108528 Piston Nut is an internal OEM component used in selected Graco industrial pump lowers. Compatibility is determined by the specific lower (fluid) section used on the machine.
- Graco High-Flo 4-Ball lower pump assemblies (selected sizes)
- Packages powered by President air motors using compatible 4-Ball lowers
- Packages powered by Viscount / Viscount II hydraulic motors using compatible 4-Ball lowers
- Packages powered by NXT air motors paired with compatible High-Flo lowers
What is the Graco 108528 Piston Nut?
The Graco 108528 Piston Nut (often shown in diagrams as “Nut, Piston”) secures the piston/rod assembly inside the pump’s lower (fluid) section. As an OEM part, it’s engineered to maintain proper alignment, sealing stack compression, and long-term durability under high pressure.
- Authentic Graco OEM internal fastener for specific 4-Ball lowers
- Critical for rod/piston retention and correct packings preload
- Designed for high-duty industrial coating and fluid transfer pumps
Key Details
| OEM Part Number | 108528 |
|---|---|
| Part Name (Catalog) | Nut, Piston |
| Used In | Selected High-Flo 4-Ball lowers (President / Viscount / NXT packages where diagram specifies 108528) |
| Typical Dimensions (approx.) | ~1.8 in × 2.4 in × 2.2 in (reference from supplier listings) |
| Installation Note | Torque per your pump manual (examples in Graco service docs range ~75–100 ft-lb depending on model). Always follow the exact spec for your lower. |
When to Replace
- Thread damage or rounding on the piston nut flats
- Unable to hold torque / loosening during operation
- Packings won’t maintain proper preload after rebuild
- Specified as a new component in a complete lower rebuild
Installation Tips (Summary)
- Clean and inspect rod, piston, spacers, and seals; replace worn parts.
- Thread the rod into the 108528 Piston Nut and tighten to the torque specified for your lower.
- Ensure packing orientation and wet-cup setup match the manual.
- After assembly, flush and pressure-test for smooth operation and leaks.
Frequently Asked Questions
Check the lower (fluid) section parts diagram in your model’s manual. If the diagram lists “Nut, Piston — 108528” you’re good. You can also share your model and serial with us and we’ll verify before you order.
Selected High-Flo 4-Ball lowers paired with President, Viscount / Viscount II, and some NXT packages. Always confirm against your lower’s exact part list.
Follow your pump manual. Graco service documents show example ranges around 75–100 ft-lb depending on the exact lower. Use only the value specified for your model.
No. This listing is for the authentic Graco 108528 OEM part (“Nut, Piston”) for compatible lowers.
Use fresh packings and seals, set correct torque, keep the wet-cup filled as specified, and flush compatible solvents after each shift. Inspect threads/flats each service cycle.
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