The Simpson Aluminum ALH4240 is a gas-powered pressure washer offering a maximum water pressure of 4200 PSI and flow of 4 GPM. (Read full specs)
Zoom on the Simpson ALH4240
The Simpson ALH4240 is a heavy duty, commercial pressure washer, that provides its users with an all-around versatile cleaning experience, and enables:
- spot cleaning of hard, paint-free surfaces and out-of-reach areas
- intense cleaning of tough, paintless surfaces
- cleaning of painted and fragile surfaces
- application of detergent and cleaning solutions
With a powerful 389 cc (11.7 hp) engine, its triplex pump delivers a pressure of 4200 PSI (roughly 70 times more than a standard garden hose) and a flow of up to 4 GPM (CETA-certified values), resulting in the Simpson ALH4240's cleaning power of 16800 Cleaning Units.
The Honda GX390 engine of this gas-powered pressure washer relies on an old-school pull-start mechanism to get started.
Gasoline storage is facilitated by a steel fuel tank with a maximum capacity of 1.6 gallon.
Design & Handling
The wheelbarrow design of the Simpson ALH4240 grants mobility and stability to the unit. The aluminum frame allows the device to remain highly durable, as it will not rust. The handle adds to the ALH4240 convenience of transport.
This model weighs 133 lbs. For this reason, it cannot be called lightweight and thus, carrying and transporting it might be somewhat challenging. A key role in its final weight is played by its 389 cc Honda GX390 engine, the triplex pump and aluminum frame. However, its two 13" pneumatic wheels play an important part in its maneuvrability, as they allow for a smooth manipulation on the job.
The Simpson ALH4240's package includes a spray gun, a wand, a pressure hose, 5 nozzles and a detergent injection feature, with a more detailed description below.
- Soap injection: Even though the device doesn't have a soap tank, detergent is supplied by a siphon hose. The detergent will be added automatically to the water when a soap nozzle is attached.
- Pressure hose: The included 50 ft ⌀3/8" high-pressure hose can be neatly stored on the unit when idle thanks to a set of convenient hooks.
- Spray gun and wand: The included classic ergonomic spray gun and its steel wand can be easily stored in a side hook.
- Nozzles: The 5 nozzles included with the device, and the respective surfaces which they’re the most suitable for, are shown in the following table.
|Concrete, brick, masonry||Use with caution||Suitable||Suitable||Suitable||Suitable|
|Siding, gutters, house||Not recommended||Use with caution||Use with caution||Suitable||Suitable|
|Fencing, deck, patio||Not recommended||Use with caution||Use with caution||Suitable||Suitable|
|Lawn equipment, boat, RV||Not recommended||Use with caution||Use with caution||Use with caution||Suitable|
Note: The shape of the nozzles above is for illustration purposes only and may differ.
Red cross: Not recommended. Green check: Suitable. Orange check: Use with caution.
- Dial-N-Wash®: Simpson’s Dial-N-Wash® is an adjustable pressure regulator that allows you to choose a desired pressure for your specific cleaning application. High, medium and low pressure settings can be switched between easily by a simple twist. Its design assures its compatibility with most pressure washer standard spray wands and standard guns with threaded fittings.
- Onboard storage: The Simpson ALH4240 features a handy storage area, which allows you to neatly store nozzles and accessories and be always prepared by having everything needed at hand.
- Safety: Safety of operation is enhanced by a trigger lock mechanism (which prevents accidental operation), a thermal relief valve (which helps to prevent internal pump damage) and a low oil protection.
- Accessories: Besides the usual owner's manual (opens in a new tab) and documentation to get you promptly started, the Simpson ALH4240 comes with wand, spray gun, pressure hose, soap hose, pressure regulator and oil.
- Emissions: The Simpson ALH4240 is EPA-approved and CARB-compliant. This means that this pressure washer can be bought and sold in each of the 50 states, including California.
The Simpson ALH4240's performance versus other pressure washers
The following charts are provided to give you an idea of how the key specs of the Simpson ALH4240 compare to similarly priced pressure washers.
- The Simpson ALH4240, with a max water pressure of 4200 PSI, has one of the highest PSI values of the gas-powered products in the $1000-1300 price range.
- With a water flow of up to 4 GPM (gallons per minute), this washer belongs to the best of the above-mentioned price range, as it can deliver a high volume of water.
- The ALH4240, with its 16800 Cleaning Units (PSI x GPM) sits at the high end of the cleaning efficiency spectrum, when compared to other devices of similar price.
As you can see from this interactive chart, when compared to other gas-powered washers between 16500 and 17000 Cleaning Units, the Simpson ALH4240 is on the average side of the price range.
Therefore, this pressure washer nicely fits in the expected budget for this kind of cleaning power.
Features and Specifications
|Water||Cold (100°F max.)|
|Engine||389 cc 11.7 HP Honda GX390 OHV 4-stroke|
|Other model numbers||60688|
|Soap injection||Via siphon hose|
|Nozzles||0°, 15°, 25°, 40°, Soap|
|Quick connect nozzles||Yes|
|Hose||50 ft, ⌀3/8|
(L x W x H)
|Approx. 38 x 23.5 x 26 in|
|Pressure control||Dial-N-Wash® + unloader valve|
|Wheels||2 wheels, ⌀13", pneumatic|
|Included accessories||Oil, steel wand, spray gun, high pressure hose, soap hose, 5 nozzles, Dial-N-Wash® pressure regulator|
|Security||Low oil, trigger lock and thermal relief valve|
Unlike many websites, we did our best to research each of the specs above. That being said, we are not immune to making the occasional mistake or omission. Should you notice any missing or incorrect values, don't hesitate to suggest improvements so we can address the issue.
Simpson has over 50 years of experience making quality products for the outdoor power equipment industry. Part of the FNA Group based in Pleasant Prairie, Wisconsin since 2006, they are a vertically-integrated company, meaning most of the parts and accessories are manufactured and assembled by them. Their manufacturing facilities are international. With the company motto "Driven by Performance", Simpson continues to offer a great variety of pressure-washing systems for the homeowner or the professional contractor.
The Simpson ALH4240 is covered under a warranty for up to 10 years. This warranty may be limited and may not cover all parts of the unit.
For more information about the warranty of Simpson pressure washers, please contact the Simpson Customer Support: 1-877-362-4271.