Compatible Machines – Quick List
The Graco 235703 Pump Repair Kit (OEM packing kit) services the fluid section on select legacy contractor-grade sprayers. Verify your exact model and series before ordering.
- Graco 390 ST / 390 STS
- Graco 395 ST / 395 STS
- Graco 450 ST
- Graco 455 ST
- Graco 490 ST
- Graco 495 ST
- Graco 190 ES (select versions)
- Graco Ultra 600 (select versions)
- Select legacy “Ultra / Ultra Plus” ST-series variants
- Select GM 3000 / LineLazer 3000 (where ST-style pump is fitted)
What is the Graco 235703 Pump Repair Kit?
It’s an OEM packing / pump repair kit that refreshes the wear components of the pump’s fluid section—restoring pressure, reducing leaks, and improving prime & finish quality on compatible machines.
Key Benefits
- OEM fit for ST / STS legacy pumps—no guesswork on sizes.
- Restores performance if you’re seeing pressure drop, material bypass, or packing leakage.
- Extends service life vs. running worn packings that score the rod or cylinder.
Kit Contents & Specs (Typical)
| Component | Material / Type | Purpose |
| Upper Packings | Leather / UHMWPE (poly) | Seal around piston/rod; maintain pressure above fluid section |
| Lower Packings | Leather / UHMWPE (poly) | Seal at lower end of pump for efficient displacement |
| Throat / Wiper Seal | Elastomer | Keeps fluid in and contaminants out at the wet cup |
| O-Rings / Gaskets | Elastomer (assorted) | Restore static seals within the fluid section |
| Packing Glands / Spacers | Metal / Polymer | Correct stack compression and alignment |
Note: Exact contents can vary by kit revision and pump series. Always match by part number 235703 and your sprayer’s model/series.
When to Use This Kit
- Visible packing leakage at the throat or wet cup.
- Pressure instability, poor atomization, or difficulty maintaining spray pattern.
- Maintenance interval reached on heavy-use contractor machines.
Fitment Guidance
- Check your nameplate for the exact model (e.g., 390 STS) and series/part number.
- Legacy “ST / STS” pumps share architecture, but sub-variant differences exist—verify before purchase.
- If your rod/cylinder is scored or pitted, consider a deeper overhaul or replacement pump assembly.
Installation Tips
- Clean disassembled parts thoroughly; avoid lint and debris in the packing stack.
- Pre-lube leather packings and follow the correct stack order & orientation.
- Torque fasteners to spec; tighten packing nut only to the point of sealing and re-check after break-in.
Frequently Asked Questions
It fits 390 ST / STS and 395 ST / STS legacy variants. Modern 390/395 models with different pump families may use different kits—check your exact series and pump part number before ordering.
Persistent dripping at the throat, difficulty building pressure, pulsation, rough spray pattern, or frequent re-priming typically indicate worn packings/O-rings.
If the rod/cylinder is scored or pitted, packings will fail prematurely. Inspect surfaces during teardown—if damage is present, replace the affected parts or consider a complete pump assembly.
Basic hand tools typically suffice. Follow Graco’s service manual for your pump. Proper cleaning, lubrication, and torque are essential for a long-lasting repair.
Prime with appropriate fluid, run at low pressure to wet and seat the packings, then gradually increase pressure. Re-check the packing nut after initial use and adjust if needed.
