Graco DutyMax GH300 Hydraulic Motor

Heavy coatings demand heavy hardware. Graco® DutyMax GH300 HD is a 3300 psi / 22.8 MPa gas-hydraulic workhorse that blasts through high-solids elastomerics, intumescents and roofing mastics without flinching. But when a hydraulic seal finally weeps or the displacement pump loses prime, you need factory-exact spares—fast. This page delivers a full OEM parts catalogue, proven compatibility guidance and expert maintenance hacks so your crew can swap, prime and spray again before deadlines bite.

Maintain & Upgrade with Precision-Engineered GH300 Parts

GH300’s heart is a two-stage system: a nine-horsepower Honda® engine drives a high-efficiency hydraulic motor, which in turn powers the MaxLife™ displacement pump. Every gasket, ball seat and piston rod in this chain is machined to micron-level tolerances so the sprayer can deliver up to 3.0 gpm (11.4 L min^-1) through tips to .047 in while maintaining a dead-flat fan. Copy-cat parts often use softer alloys or generic O-rings that swell in hot solvent—robbing you of pressure and coating consistency.

Four Reasons Pros Stay Genuine

Oil-Tight Reliability. Viton™ and PTFE seal stacks are rated to 400 °F hydraulic oil, preventing foaming and heat-fade during 10-hour roof shifts.
MaxLife Surface Hardening. Pump cylinders receive a proprietary chrome-nickel diffusion layer that outlasts plated imports by 2-to-1 on abrasive silica-filled block fillers.
Drop-In Serviceability. ProConnect™ modules let a single tech swap the entire pump in under 60 seconds—no pullers, presses or shaft realignments.
Full backed by Graco Warranty.

Core Specifications at a Glance

Max Working Pressure	3300 psi / 22.8 MPa
Max Flow (1 gun)	3.0 gpm / 11.4 L min^-1
Engine	9 HP Honda® GX270 with Oil-Alert
Hydraulic Motor Repair Kit	248977 (seals, bearings, piston)
Displacement Pump Repair Kit	24M725 (check-valve & seat)
Inlet Filter	189920 stainless 60-mesh
Outlet Size	3/8 in NPT (includes whip-hose swivel)

Cross-Rig Compatibility—One Cart, Many Sprayers

Stocking one hydraulic seal kit that fits multiple rigs slashes inventory clutter. The GH300 parts roster dovetails with several other high-output Graco sprayers, so you can cover the whole fleet with minimal SKUs:

GMax II 7900—shares the same 3300 psi gun/filter set and Honda GX270 engine; your graco 7900 paint sprayer can accept the identical 3/8 in outlet whip hose for reduced whip-lash.
Magnum Pro X7 & ProX9—ProConnect pump modules and cylinder O-rings interchange (use adapter 17P186); perfect for rental yards balancing pro and DIY fleets.
Magnum LTS 17 & Magnum X5—RAC X™ tip guards, filters and most gun seals are identical, simplifying trailer toolboxes.
Ultra 395 / 495 / 595—gun repair kits and tip seats mirror the GH300, making cross-crew training easy.
Graco Whip Hose Line-Up—all 1/4 in and 3/8 in whip hoses are rated 3300 psi+, covering every sprayer on this list.

Must-Have Accessories that Protect the Pump

A replacement pump fixes today’s failure—but pairing it with the right accessories prevents tomorrow’s. Here are five add-ons trusted by roofers, tank liners and civil contractors:

Graco Spray Gun Parts Kit. Contractor PC™ gun filter (287032), spring, seal and needle rebuilds in minutes, restoring a razor-sharp fan and cutting back-pressure at the pump.
Heavy-Duty Whip Hose. A 3 ft 3/8 in whip hose rated 3300 psi reduces wrist torque while dampening pressure spikes—extending hydraulic seal life by up to 20 %.
Airless Paint Sprayer Attachments. Add a 20 in tip extension and inline gun swivel to hit overhead deck pans without kinking the spray hose.
Pump Armor® Over-Winter Kit. A gallon of anti-freeze/anti-rust fluid plus quick-connects stops corrosion inside the MaxLife cylinder during seasonal storage.
Job-Site Drop Crate. Pack a hydraulic motor kit, displacement pump kit and graco spray gun parts in a stackable crate; swap on-site and ship the failed core for rebuild.

Pro Maintenance Blueprint—Five Habits for 3 Year Pump Life

1. Log Oil Hours. Change hydraulic oil every 250 hours and replace the return filter at 500 hours.
2. Flush Warm. Run 100 °F water or compatible solvent at half pressure until clear—never shut down with solids in the cylinder.
3. Lube the Throat. Two drops of TSL™ every break keeps Chromex rods mirror-bright.
4. Rotate Guns. Alternating between two Contractor PC guns splits swivel wear and keeps packings concentric.
5. Store Pressured. Leave 200 psi hydraulic pressure in the system overnight to seat the ball and prevent drips.

Ready to Re-Power Your GH300?

Open the digital parts diagram, choose your hydraulic motor kit, displacement pump kit and accessory bundle, then hit Add to Cart. One freight fee, one tracking code, one bullet-proof fix—see you on tomorrow’s jobsite.