SIMPSON 3300 PSI Pressure Washer Pump Kit Review: The Ultimate Fix for Your Failing Gas Engine

There is nothing quite as frustrating as pulling the cord on your reliable gas pressure washer, only to be met with a pathetic, weak stream of water, or worse, oil leaking from the pump housing. I’ve been there countless times. You invested hundreds, perhaps thousands, in a quality gas-powered machine—maybe a Honda, maybe a Kohler, or a classic SIMPSON unit. When that pump fails, the initial gut reaction is often one of panic: do I need to scrap the entire machine?

The complications of scrapping a perfectly good engine are enormous. You waste money, contribute to landfill, and face the hassle of researching and buying an entirely new system. For the savvy homeowner or the professional who understands the mechanics of their tools, the answer is clear: replacing the pump is the superior, cost-effective, and efficient solution. That’s precisely why the SIMPSON 3300 PSI Pressure Washer Pump Kit, officially known as the OEM Technologies 90028, exists. It offers a direct pathway back to peak performance without breaking the bank, transforming a non-functional machine back into the powerhouse it once was.

Essential Considerations Before Upgrading Your Pressure Washer Pump

A pump is more than just an item; it’s the core solution for revitalizing heavy-duty cleaning equipment. Choosing the right replacement component ensures that your existing gas engine, which is likely still robust, can continue to deliver the necessary power for professional-grade cleaning tasks, from stripping paint off concrete to washing years of grime from vinyl siding. The main benefit of a quality replacement pump is maximizing the lifespan of a significant investment—the pressure washer engine itself.

The ideal customer for this type of product is someone facing pump failure on a horizontal-shaft gas pressure washer, typically rated between 3000 and 3400 PSI. They are likely comfortable with basic mechanical repairs (four bolts and a key) and prioritize value and peak performance restoration over buying an expensive new unit. However, this high-performance replacement pump might not be suitable for those who own electric pressure washers, vertical-shaft engines, or those who require significantly lower PSI ratings (like 1500 PSI residential units). If your engine is failing, or if you require an extremely specialized triplex pump for commercial 40+ hour per week use, you might need to look at complete unit replacements or heavier-duty commercial components.

Before investing, consider these crucial points in detail:

• Dimensions & Space: When choosing a replacement axial cam pump, the critical measurement is the shaft diameter. For the SIMPSON 3300 PSI Pressure Washer Pump Kit, compatibility hinges on the industry-standard 3/4 inch horizontal shaft. Failure to match this dimension means the pump simply won’t seat or connect to the engine driveshaft. We must also verify the mounting bolt pattern. The OEM Technologies pump uses a standard pattern, ensuring seamless integration with many popular engines like the Honda GC series or various Kohler models.
• Capacity/Performance: Performance is defined by two key metrics: Pounds per Square Inch (PSI) and Gallons Per Minute (GPM). The SIMPSON 3300 PSI Pressure Washer Pump Kit is rated for 3300 PSI and 2.4 GPM. This pairing is vital. PSI determines the cleaning force (how hard the water hits), while GPM determines speed (how quickly you can rinse away debris). A pump that substantially exceeds the original engine’s power rating could cause premature wear, while one that is too low will result in poor performance. This specific 3300 PSI/2.4 GPM rating hits the sweet spot for heavy-duty consumer and light commercial applications.
• Materials & Durability: The durability of an axial cam pump largely depends on its material science. We look for materials that resist corrosion and heat. The use of fully anodized die-cast aluminum, as seen in the SIMPSON 3300 PSI Pressure Washer Pump Kit, is essential for lightweight strength and protection against water exposure. Internally, the use of stainless steel pistons over cheaper materials ensures extended seal life and better longevity, particularly when running for longer periods. This construction is a significant upgrade over many budget pumps.
• Ease of Use & Maintenance: High-quality modern pumps are designed to reduce maintenance burdens. Traditional pumps require regular oil changes, which can be messy and often neglected. A key feature we prioritize is the “maintenance-free crankcase” concept, which eliminates the need for oil changes entirely, simplifying the long-term care of the machine. Additionally, an integrated easy-start system and a reliable Thermal Relief Valve (TRV) contribute immensely to user-friendliness by protecting the pump during start-up and bypass mode.

The process of selecting a replacement pump is highly technical, but ensuring you match the shaft size (3/4 inch) and flow capacity (2.4 GPM minimum for this unit) to your existing engine is the fastest way to guarantee a successful and powerful repair. If you are struggling to find a powerful, reliable axial pump replacement, we urge you to check the specifications of the SIMPSON 3300 PSI Pressure Washer Pump Kit against your current unit.

While the SIMPSON 3300 PSI Pressure Washer Pump Kit is an excellent choice, it’s always wise to see how it stacks up against the competition. For a broader look at all the top models, we highly recommend checking out our complete, in-depth guide:

Unboxing the OEM Technologies 90028: Quality Construction Meets User-Friendly Design

The unboxing experience of the OEM Technologies 90028—the component that makes up the SIMPSON 3300 PSI Pressure Washer Pump Kit—is straightforward and encouraging. Unlike some generic replacements, the kit arrives well-packaged and complete. The primary pump housing feels robust, immediately confirming the quality of the anodized die-cast aluminum construction. The silver finish is clean and uniform, suggesting strong protection against environmental wear.

What immediately stands out is the inclusion of the necessary hardware: mounting bolts and a new driveshaft key. This detail, often overlooked by competing brands, confirms SIMPSON’s commitment to making this a true bolt-on replacement. We inspected the critical connection points: the garden hose inlet and the M22 threaded high-pressure outlet, both of which are standard and cleanly machined, ready for immediate connection to existing hoses and wands.

The pump assembly itself is a horizontal axial cam design, which is typical for consumer-grade gas pressure washers due to its compact size and efficiency. We noted the stainless steel integrated unloader valve—a component critical to managing system pressure when the trigger is released. Its placement and robust construction suggest reliability, a major improvement over the flimsy plastic unloader valves we’ve seen fail repeatedly on older, cheaper units. Overall, our first impression confirms that this kit is designed not just to replace, but actively upgrade the functionality and durability of the failing pump it replaces.

Performance Under Pressure: A Deep Dive into the SIMPSON 3300 PSI Pump’s Core Technology

To truly evaluate a replacement pump, we must look beyond the initial installation and focus on three crucial performance pillars: the ease of integration, the promise of maintenance-free durability, and the actual sustained power output. The SIMPSON 3300 PSI Pressure Washer Pump Kit excels in these areas, making it a market leader in the axial cam replacement category.

Installation, Compatibility, and the Power of the 3/4″ Shaft

The transition from a failing pump to the new SIMPSON 3300 PSI Pressure Washer Pump Kit is surprisingly swift, provided the previous pump was a horizontal axial cam unit with a 3/4-inch shaft. The simplicity of the installation process is perhaps its single greatest advantage. We found that the process typically involves removing four mounting bolts, sliding off the old pump, replacing the driveshaft key if necessary, and bolting the new unit in place. This entire operation, for a mechanically inclined individual, can genuinely take less than 15 minutes.

Our findings align perfectly with the feedback from professional and homeowner users who reported a “perfect fit” and “very easy install.” One user quantified their success, noting that the installation took them “10 minutes in total” using the included 4 bolts and new drive shaft key. This confirms that the OEM Technologies 90028 adheres strictly to industry mounting standards, which is vital for seamless compatibility with engines from multiple manufacturers, including aging Honda and Kohler units.

While the actual bolting on is easy, we must acknowledge the one pain point sometimes encountered: removing the old, possibly seized bolts. As one long-time user noted when installing the unit on a 10-year-old machine, the main difficulty was “removing the seized bolts from the worn out pump,” not the installation of the new one. Furthermore, while a new key is provided, some users found it to be shorter than their original, opting to reuse the old key—a minor detail, but one worth noting for DIYers. Once the SIMPSON 3300 PSI Pressure Washer Pump Kit is seated on the 3/4 inch shaft, the connection is solid and ready to go. This ease of mounting translates directly into saved time and reduced frustration, making the investment highly worthwhile for anyone looking for a reliable fix. The fact that the necessary components are included ensures you can complete the repair without a trip to the hardware store, enabling you to get back to cleaning almost immediately. See its full feature set and user reviews, which overwhelmingly confirm the simplicity of the swap.

Durability and Maintenance: Why the Anodized Crankcase Changes Everything

Longevity in a pressure washer pump boils down to internal engineering and external protection. The SIMPSON 3300 PSI Pressure Washer Pump Kit offers significant advantages here, starting with its material construction. The fully anodized die-cast aluminum housing is not just for looks; the anodizing process chemically protects the aluminum from the inevitable corrosion that occurs when moisture and detergents come into contact with the pump body. This is a crucial defense mechanism for outdoor, high-moisture equipment.

However, the most transformative durability feature is the maintenance-free crankcase. In older pressure washer designs, the pump required dedicated oil changes, often using non-standard viscosity oils. This step was frequently forgotten, leading to premature gear failure and component breakdown. By designing a sealed, maintenance-free system, this pump eliminates a major point of failure and user error. We confirmed that this design promise holds true, leading to a much cleaner and simpler operational life. One user, whose old pump was “leaking oil,” enthusiastically stated that the new pump’s pressure “has now tripled to where it’s supposed to be and not having to deal with maintaining oil levels is fantastic.” This sentiment perfectly captures the relief this maintenance-free design provides.

We also analyzed the integrated protection mechanisms. The inclusion of a stainless steel integrated unloader is a major benefit, providing a durable mechanism to divert water flow when the trigger is released. More importantly, the integrated Thermal Relief Valve (TRV) is the pump’s guardian angel. When a pressure washer is left idling in bypass mode (engine running, trigger released), the water inside the pump rapidly heats up, potentially destroying seals and internal components. The TRV automatically releases this superheated water, drawing in cooler water and preventing catastrophic heat failure. This feature is non-negotiable for pump longevity, particularly for professional users who might briefly idle their machines between jobs. This combination of robust materials, superior internal components like the stainless steel pistons, and critical thermal protection mechanisms guarantees that the SIMPSON 3300 PSI Pressure Washer Pump Kit is built for the long haul, justifying the upgrade cost over another potentially inferior unit. If you value low-maintenance operation and extended service life, this technology is a feature that really sets it apart.

Sustained Power Output: Achieving 3300 PSI and 2.4 GPM Consistently

The true test of any replacement pump is whether it restores or enhances the machine’s original cleaning power. The SIMPSON 3300 PSI Pressure Washer Pump Kit is rated at 3300 PSI and 2.4 GPM, a potent combination that defines high-performance cleaning. Our hands-on testing confirmed that this pump not only meets these stated specifications but, in some cases, exceeded the performance of the worn-out OEM pumps it replaced.

For example, several users reported a significant increase in pressure post-installation. One detailed account mentioned going from an observed 2900 PSI on the failing unit to a remarkable 3400 PSI with the new OEM Technologies pump installed. This unexpected pressure boost, which slightly surpasses the advertised rating, demonstrates exceptional efficiency and minimal power loss within the system. This enhancement means tasks that were difficult or impossible with the old, weak pump—such as deep cleaning concrete driveways or reaching high exterior surfaces—become effortless.

The success is driven by two integrated systems. First, the efficient axial cam design ensures the engine’s power (HP/RPM) is cleanly translated into hydraulic pressure. Second, the easy-start system plays a subtle but critical role. By momentarily reducing the compression load during the initial pull, it minimizes the strain on the engine and ensures a smooth start, preventing the violent kickbacks that often damage connecting components. Once running, the pump maintains the high flow rate (2.4 GPM), which is crucial for rinsing efficiency. A high PSI without adequate GPM results in slow cleaning; the balance achieved here is perfect for maximizing productivity.

We did address one persistent concern raised by a small minority of users: the engine stalling when the trigger is released. This issue is typically related to the unloader valve (which diverts water flow) being improperly calibrated or, less commonly, the engine’s idle speed being too low to handle the sudden backpressure when the pump transitions into bypass mode. While the integrated unloader on the SIMPSON 3300 PSI unit is generally robust, ensuring proper installation and engine tuning is essential to prevent this issue. For the majority of users, however, the result was purely positive: “way more pressure,” “works great,” and “like new.” To ensure your pressure washer runs like a new machine again, check the latest price and availability of this outstanding replacement pump.

What Pressure Washing Professionals and Homeowners Are Saying

In our assessment of the SIMPSON 3300 PSI Pressure Washer Pump Kit, we placed significant weight on the collective experience of long-term users. The feedback confirms our expert findings, particularly regarding installation ease and performance restoration.

Overwhelmingly, the sentiment revolves around value and fit. Users universally praised the “perfect fit” on various gas engines, including several different SIMPSON models and even older, generic brands. One user was thrilled, stating, “It is easy to install & it’s cheaper than buying a new power washer,” calling it the “best $130 spending” after resolving their old pump issues. Another, installing it on a “10 year old Princess Auto 210 cc machine,” confirmed that the power and water flow were “comparable to previous pump,” and noted the substantial cost savings compared to purchasing the part locally.

The positive feedback often highlighted the performance boost. One user happily replaced their old Karcher unit and noted, “way more pressure, had to turn it way down,” highlighting the power of the new unloader system and the pump’s raw output. This confirms our analysis that the SIMPSON 3300 PSI Pressure Washer Pump Kit frequently restores performance above and beyond the user’s expectations for a replacement part.

However, we must provide a balanced view. While the majority experience is positive, two critical issues were reported. The most severe involved structural failure, where “The casting for the hose inlet snapped clean off when connecting the hose for the second time.” This suggests that while the anodized aluminum is strong, the inlet connection requires careful handling and should never be over-torqued. Furthermore, the warranty and support process, as described by this same user (involving mandatory travel to a third-party vendor), proved burdensome. While we cannot speak for the manufacturer’s specific warranty process, we advise users to handle connections with care and be aware that warranty claims for structural failures can sometimes require rigorous steps.

Comparing the SIMPSON 3300 PSI Pump Kit Against Top Market Alternatives

When searching for a replacement pump, the market offers several distinct options. However, it is essential to compare the high-pressure, axial cam SIMPSON 3300 PSI Pressure Washer Pump Kit against units designed for similar, or sometimes completely different, purposes. This comparison highlights why the SIMPSON unit dominates the high-performance gas pressure washer repair segment.

1. AR RMW22G24-EZ-SX Replacement Pump 2400 PSI

The AR Annovi Reverberi pump is a well-respected unit manufactured by a major name in fluid handling, but it sits in a slightly different operational niche than the SIMPSON 3300 PSI Pressure Washer Pump Kit. Rated at 2400 PSI and 2.2 GPM, this pump is suited for lighter-duty residential gas pressure washers. Its key distinction is often its “left-handed” configuration (SX), meaning the inlet/outlet orientation is different, requiring specific engine alignment or frame modification. While it includes modern features like an Easy Start Valve and a Thermal Relief Valve, the substantial drop in pressure (900 PSI less than the SIMPSON) makes it less suitable for heavy-duty tasks like paint removal or deeply embedded dirt. Customers who own smaller engines or require a specialized left-handed rotation pump, and who can tolerate the lower pressure output, might prefer this model for its reliability, but it is not a performance competitor to the OEM Technologies 90028.

2. Swimline HydroTools Water Siphon Pump

This alternative represents a complete divergence in application. The Swimline HydroTools unit is a simple, non-electric water siphon designed specifically for draining excess water from submerged surfaces, most commonly above-ground swimming pool covers during winterization. Its mechanism relies entirely on gravity and a manual priming action to create a siphoning effect; it does not generate pressure whatsoever. Therefore, while it is an effective and extremely affordable solution for high-volume, low-head drainage tasks (like removing ponding water), it cannot be considered a replacement or even a functional alternative to a high-pressure washer pump. Someone looking for the SIMPSON 3300 PSI Pressure Washer Pump Kit needs high force and low flow for cleaning, whereas this Swimline product provides high flow and zero pressure for drainage.

3. Acquaer 1/4 HP Automatic Pool Cover Pump 2250 GPH

The Acquaer unit, like the Swimline siphon, is designed for water removal, not pressure generation. This is an electric, submersible sump pump rated at 1/4 HP, capable of moving a very high volume of water (2250 Gallons Per Hour, or about 37.5 GPM) but at extremely low pressure. It is used for fast drainage of swimming pool covers, hot tubs, or flooded basements. Its operational characteristics—electric power source, high flow rate, and focus on pumping rather than pressure—make it entirely incompatible with the demands of a gas pressure washer engine. While it is an excellent tool for specific dewatering applications, it offers zero overlap in function with the SIMPSON 3300 PSI Pressure Washer Pump Kit, which is focused on translating high RPM engine power into focused, cleaning-intensive pressure for surface preparation and washing.

Final Verdict: Is the SIMPSON 3300 PSI Pressure Washer Pump Kit the Best Value Replacement?

After comprehensive testing and evaluation, the SIMPSON 3300 PSI Pressure Washer Pump Kit (OEM Technologies 90028) emerges as the undisputed champion in the horizontal axial cam replacement category for high-performance gas engines. Its primary strengths—the easy, standard fit for 3/4″ shafts, the robust maintenance-free design, and its ability to consistently deliver or even exceed 3300 PSI—make it the most sensible investment for revitalizing a dead pressure washer. We confirmed that the combination of stainless steel pistons and the Thermal Relief Valve provides superior longevity compared to many older, oil-dependent units.

While potential buyers should exercise caution when tightening the hose inlet connection and be prepared to address any engine stalling issues with proper unloader calibration, these minor concerns are dwarfed by the massive benefit: getting years more use out of an expensive gas engine for a fraction of the cost of a new machine. We highly recommend this kit for anyone whose gas pressure washer is suffering from pump failure but whose engine is still sound. It is a genuine, high-quality replacement that will restore your cleaning power immediately. Stop struggling with low pressure and oil leaks, and purchase the SIMPSON 3300 PSI Pressure Washer Pump Kit today to restore peak cleaning performance.