General Pump Kit 309 3/8" BSP-F ET Series Valve Kit - 1709

Restore Full Pressure and Performance in One Service

General Pump Kit 309 is a complete inlet and outlet valve replacement kit for ET Series triplex plunger pumps. It includes all six valve assemblies (three inlet, three outlet) needed to service every cylinder in the pump, restoring proper compression, fluid control, and operating pressure in a single repair session. Kit 309 services high-pressure ET-series triplex pumps, including models such as the ET1505, ET1506, ET1507, ET1508, and ET1509, in both solid shaft and hollow shaft configurations. Before purchasing, compatibility with the specific ET-Series model should be confirmed before ordering, since bore size (15 mm vs. 18 mm) determines the correct kit.

The primary benefit is straightforward: Kit 309 restores pumps to factory strength by replacing every high-pressure valve and its associated seals, springs, and seats in one matched set, eliminating the guesswork and risk of mixing old and new components.

Why You'll Love General Pump Kit 309 Repair Kits

If your ET pump is showing symptoms like low pressure or pulsating pressure, slow pressure build, or uneven spray at the gun, worn valves are the most likely cause. Here's what Kit 309 delivers once installed:

• Fast pressure recovery – Replacing all six valve assemblies at once restores the sealing function across all three cylinders simultaneously. Replacing worn valves prevents common symptoms like sudden pressure drops, hard pulsation, and rough pump operation that slow down every job.

• Prevents costly downtime – Repair kits help avoid unexpected pump downtimes. Having Kit 309 on the shelf means a contractor or fleet manager can swap valves during a scheduled maintenance window instead of scrambling for parts mid-season when a pump goes soft on a job site.

• Matched OEM components – Every valve, spring, O-ring, and seat in Kit 309 is manufactured to General Pump ET tolerances. The inlet and outlet springs are different sizes (6×12 coil for inlet, 6.2×10.4 for outlet), ensuring each valve seats at the correct force for its role in the pump cycle.

• Extends pump life – Fresh valves that seal correctly protect the plungers, sleeves, and manifold bore from cavitation and vibration damage. Neglecting leaking valves lets pressure imbalances travel downstream, wearing out parts that cost far more to replace than a valve kit.

• Simplifies maintenance planning – One SKU, one kit, one service interval. Instead of tracking individual valve part numbers and sourcing O rings, springs, and seats separately, Kit 309 bundles everything for a full valve refresh in a single package.

What Makes General Pump Kit 309 Different

Most pump owners who try to save money by replacing only the worst-looking valve, or by substituting generic aftermarket parts, end up with uneven performance across the three cylinders. One fresh valve and two worn ones create a "weak cylinder" condition where pressure fluctuates with each plunger stroke.

Kit 309 solves this in three specific ways:

Engineered for ET Series geometry. The valve pocket depth and seat angle in ET pumps are specific to that platform. Kit 309 valve seats and guides match those dimensions exactly, which is why the kit includes dedicated inlet valve guides (Part #36211951) and complete outlet valve subassemblies (Part #36719301) rather than generic drop-in balls and seats.

All valves replaced at once. The kit ships with six complete valve assemblies, enough to service every cylinder. Each cylinder uses one inlet valve and one outlet valve, and replacing all six together eliminates the possibility of one lagging cylinder dragging down total system output. Generic kits sometimes ship with fewer than six assemblies or reuse existing springs, which defeats the purpose of a full refresh.

Consistent material quality. Valve components use hardened or stainless steel capable of handling the 2,610 PSI discharge pressure typical of ET1505 and ET1506 models at 3,400 RPM. The O rings are chemical-resistant elastomers (typically Buna-N) rated for common pressure washer detergents and inlet water temperatures up to 165°F (74°C). Cheaper aftermarket valves often use softer metals that erode within weeks under continuous commercial duty, sending you right back to square one.

The kit is suitable for commercial or industrial pressure washers running continuous-duty cycles on 4 GPM rigs at 3,000–4,000 PSI.

How Kit 309 Works in Your General Pump ET Series

Inlet and outlet valves control the direction of water flow in the pump. Pressure washers require a properly functioning valve system to maintain pressure; when valves leak or stick, the pump loses its ability to build and hold output. Here's the cycle Kit 309 parts support:

Valve Function During Pump Operation

1. Inlet stroke: water enters through suction valves. As each plunger retracts inside its cylinder, pressure drops below inlet supply pressure. The inlet valve opens, letting water flow into the cylinder. The corresponding outlet valve stays closed, preventing backflow from the high-pressure discharge side.

2. Compression stroke: discharge valves take over. The plunger reverses direction and compresses the water. The inlet valve closes to prevent water from being pushed back into the supply line. The outlet valve opens, and pressurized water exits toward the spray gun or distribution manifold.

3. Cycle repeats at operating speed. At 3,400 RPM, the three plungers fire in sequence, and each valve opens and closes thousands of times per minute. Worn seats or weak springs let water slip past during the closed phase, bleeding off pressure. Kit 309 components restore tight sealing on every cycle, maintaining stable output and smooth flow.

Installing General Pump Kit 309 on an ET Series Pump

Installation is a straightforward job for anyone comfortable with basic mechanical work. A careful user with standard tools can typically complete the swap in 2–3 hours. Follow safe lockout and depressurization procedures before starting.

1. Prepare the system and work area. Shut off the engine or motor. Release all system pressure by squeezing the trigger with the supply water off. Disconnect high-pressure hoses and allow the pump to cool if it has been running.

2. Access the valve caps. Remove the ET pump's manifold caps or plugs covering each valve stack. Use the correct socket or wrench, and note the orientation of each cap for reassembly. Keep fasteners organized by position.

3. Remove old valves and O rings. Gently extract each valve assembly using picks or needle-nose pliers. Inspect the removed parts for pitting, scoring, debris buildup, or broken springs. Discard all worn seats, rings, and springs; do not mix old and new components.

4. Clean the valve pockets. Wipe each valve bore with a lint-free cloth. Check for scoring or corrosion on the manifold surface where the valve seat contacts. If the bore is scored or pitted beyond a surface blemish, the manifold may need professional attention before new valves will seal correctly.

5. Install new Kit 309 components. Seat each new valve, spring, and O-ring from the kit into the correct position. The inlet valve guides, balls, seats, and springs go into the suction side; the complete outlet valve subassemblies go into the discharge side. Make sure every O-ring is seated flat and not pinched.

6. Reassemble and torque to spec. Reinstall valve caps or plugs. The ET pump manual specifies torque values by position: 30 ft-lbs (40 Nm) for Position 24 and 26 bolts, and 9.6 ft-lbs (13 Nm) for Position 50 bolts on some models. If threads are lubricated, reduce torque by 20% to avoid distortion.

7. Test for leaks and performance. Reconnect supply and discharge hoses. Prime the pump with clean water, start the engine at low RPM, and check every connection for leaks. Gradually bring the system up to operating speed and confirm that pressure and flow match expected levels for your ET model.

General Pump Kit 309: Product and O Rings Details

This section is a quick-reference overview for technicians, buyers, and parts managers.

• Application: Valve replacement kit for General Pump / Interpump ET Series triplex plunger pumps used on cold-water pressure washer systems rated up to 2,610 PSI

• Typical compatible models: ET1505, ET1506, ET1507, ET1508, ET1509 (solid shaft and hollow shaft variants); Kit 309 should be matched to the exact pump model before purchasing

• Components included: Kit 309 includes all necessary parts for pump maintenance: 3 inlet valve guides, 6 valve balls, 6 valve seats, 6 springs (two distinct sizes for inlet and outlet), 12 O-rings, and 3 complete outlet valve subassemblies; quantity totals six complete valve assemblies

• Materials: Hardened or stainless steel valve balls and seats; corrosion-resistant steel springs; Buna-N (nitrile) elastomer O-rings

• Operating environment: Designed for pumps running at 3,400 RPM in commercial duty cycles with clean water and compatible detergents; max inlet water temperature 165°F (74°C); max inlet pressure 125 PSI

• Port reference: ET Series pumps use 3/8-19 BSP-F discharge and 1/2-14 BSP-F inlet threads

• Pricing: MSRP is $124.80; Kit 309 is currently priced at $99.84

• Related kit: General Pump Kit 01, which includes 6 check valves and O-rings, is priced at $56.47 and serves different maintenance needs

Who General Pump Kit 309 Is For

Choose Kit 309 if your operation depends on ET Series pump uptime and you need a ready solution for valve-related performance loss.

• Professional pressure washing contractors – Operators running skid-mounted or trailer-mounted rigs based on ET pumps for house washing, concrete cleaning, and commercial building exteriors. Keeping a kit on the truck means a mid-job pressure drop turns into a same-day fix instead of a lost contract.

• Fleet and facility maintenance teams – Wash bays and maintenance shops using ET-based pressure washers daily on trucks, buses, forklifts, and plant equipment. When the pump runs 6–8 hours a day, valves wear faster than in occasional-use setups, and a stocked kit eliminates parts-sourcing delays.

• Agricultural and ranch operations – Owners cleaning tractors, implements, livestock facilities, and heavy equipment. Dirty or sediment-laden water accelerates valve seat wear; having Kit 309 on hand before the busy season prevents downtime when it matters most.

• Equipment rental and service centers – Rental yards maintaining multiple ET pumps benefit from standardized valve overhauls. One kit per pump, same procedure every time, faster turnaround between rentals.

If your pressure washer uses a General Pump ET unit and shows signs of valve wear, Kit 309 is the direct solution for a full valve refresh.

Maintaining Your ET Pump After Installing Kit 309

Fresh valves are a starting point. Ongoing care determines whether those new parts last a full season or wear out in weeks.

• Use clean, filtered water. Install an inlet strainer or sediment filter upstream of the pump. Sand, grit, and mineral scale are the fastest killers of valve seats and O rings. Check and clean the filter before every shift.

• Monitor pressure and pulsation. Mount a pressure gauge on the discharge side if one isn't already installed. A 10–15% drop from baseline pressure, or rhythmic pulsation at the gun, signals early valve or seal degradation. Catching it early means a simple parts swap instead of manifold damage.

• Follow oil-change intervals. Change crankcase oil after the first 50–100 hours of operation to flush out break-in particles. After that, change at the interval specified in your ET pump manual. Use non-detergent 30W oil unless the manufacturer specifies otherwise. Milky oil means water intrusion; find and fix the leak before running the pump again.

• Avoid extended dry running. Running the pump without water or leaving the trigger closed for long periods without an unloader causes heat buildup and cavitation inside the valve chambers. Both conditions destroy new valve seats and O rings rapidly.

• Winterize before freezing weather. Flush detergents out of the system with clean water, then run pump-saver or RV antifreeze through the internal passages. Drain all lines and store the pump in a frost-free location. Frozen water inside the manifold can crack valve pockets and split O rings.

Frequently Asked Questions About General Pump Kit 309

Which pumps does General Pump Kit 309 fit? Kit 309 is designed for ET series pumps, including models like the ET1505, ET1506, ET1507, ET1508, and ET1509 in both solid shaft and hollow shaft configurations. It does not fit other General Pump families such as the TS or CW series. Always confirm your specific model number against the current General Pump parts list before ordering.

How do I know it's time to use Kit 309? Symptoms like low pressure or pulsating pressure, slow pressure build, uneven spray patterns, or noisy pump operation during the compression stroke all point to worn inlet or outlet valves. Pulling one valve cap and inspecting the seat and ball for pitting or erosion confirms the diagnosis.

Can a DIY user install Kit 309? Yes. A mechanically inclined user with a socket set, torque wrench, picks for O-ring removal, and lint-free cloths can complete the job in 2–3 hours. No proprietary tools are required. Larger commercial fleets may prefer professional service for documentation and warranty purposes.

How often should ET pump valves be replaced? Valve life depends on water quality, detergent use, inlet temperature, and daily run time. In heavy commercial use, valves typically need inspection or replacement every few hundred operating hours. Light-duty or residential-frequency users may go considerably longer between services.

Do I need any special tools? Standard sockets or wrenches sized for the ET manifold caps, a torque wrench capable of reading 9.6–30 ft-lbs, O-ring picks, and clean cloths. That covers the full installation.

Will Kit 309 fix a pump with other problems? Replacing the valve assemblies can restore the sealing function, but Kit 309 replaces only inlet and outlet valves. Scored manifold bores, cracked plungers, worn packing seals, or failing crankshaft bearings require separate parts or a more complete rebuild. If you install Kit 309 and performance does not improve, inspect those other components next.

Bring Your ET Pump Back to Full Operating Pressure

General Pump Kit 309 is the fastest path from a soft, pulsating ET pump to full factory-spec output. Six matched valve assemblies, purpose-built springs, and fresh O rings go in during a single maintenance session, and the pump comes out the other side delivering consistent pressure across all three cylinders.

Sourcing individual valves, springs, and seals piecemeal takes more time, costs more in shipping, and risks mismatched components that leave one cylinder underperforming. Kit 309 eliminates that problem with one part number and one install procedure.

Add Kit 309 to your cart and schedule your next valve service before the busy season starts. Your ET pump, and your production schedule, will be ready.