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Simpson ALH4240 Spec Review

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)

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Description

The SIMPSON ALH4240 is designed to meet the rigorous demands of the cleaning pro. Heavy-duty pressure washers with flow and reliability. Perfect for contractors who specialize in deck cleaning, wood restoration, paint preparation, graffiti removal, and all other professional cleaning services. (source: Simpson (opens in a new tab))

Zoom on the Simpson ALH4240

In a nutshell, the Simpson ALH4240 is a heavy duty, commercial pressure washer, which not only offers an all-around versatile cleaning experience, but that also allows:

  • spot cleaning of hard, unpainted surfaces and high-reach cleaning
  • thorough cleaning of hard, paint-free surfaces
  • cleaning of painted and frail surfaces
  • applying detergent and cleaning solutions

Its power characteristics and design, its main features and all its additional features are presented ahead.

Power

The Simpson ALH4240 in use

The Simpson ALH4240

The Simpson ALH4240's triplex pump, powered by an impressive 389 cc (11.7 hp) engine, can provide a pressure of up to 4200 PSI (approximately 70 times more than a standard garden hose) and a flow of up to 4 GPM (CETA-certified values). The Simpson ALH4240 thus has a 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 ensures the device's durability, 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, the unit is mobile thanks to its two 13" pneumatic wheels, which add to its movability and allow it to be manipulated smoothly on the job.

Main Features

The Simpson ALH4240 comes with a spray gun, a wand, a pressure hose, 5 nozzles and a detergent injection feature, which are detailed below.

  • Soap injection: Detergent is fed in through a siphon hose, since the device lacks a soap tank. Whenever a soap nozzle is connected, the detergent is automatically added to the water.
  • Pressure hose: A neat storage for the included 50 ft ⌀3/8" high-pressure hose is facilitated by 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.
 


15°

25

40°

Soap
Concrete, brick, masonryUse with cautionSuitableSuitableSuitableSuitable
Siding, gutters, houseNot recommendedUse with cautionUse with cautionSuitableSuitable
Fencing, deck, patioNot recommendedUse with cautionUse with cautionSuitableSuitable
Lawn equipment, boat, RVNot recommendedUse with cautionUse with cautionUse with cautionSuitable

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.

Other Features

Some of the accessories of the Simpson ALH4240

Some of the included accessories

  • 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: With the Simpson ALH4240's handy storage area, you’ll always have all the necessary nozzles and accessories at hand and thus, you’ll be fully prepared for any job.
  • Safety: Safety of operation is enhanced by a thermal relief valve (which helps to prevent internal pump damage), a trigger lock mechanism (which prevents accidental operation) and a low oil protection.
  • Accessories: Included with the Simpson ALH4240 are also the owner's manual (opens in a new tab) and some basic documentation to get you promptly started, along with several accessories, such as spray gun, pressure regulator, soap hose, wand, oil and pressure hose.
  • 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.

Product Videos

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, which can reach up to 4200 PSI, has one of the higher pressure outputs of the gas-powered units that cost between $700 and $800. If your priority is the highest possible power of the water stream, in this price range, we suggest checking out the Pressure-Pro PP4440K, which reaches up to 4400 PSI.
  • 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.
  • Reaching up to 16800 Cleaning Units (PSI x GPM), the ALH4240 is one of the more efficient amongst its similarly priced peers. If you consider the highest overall cleaning power as a really important factor, the Pressure-Pro PP4440K and its 17600 Cleaning Units has one of the highest cleaning efficiency of all the similarly priced units.
According to our stats, the following comparison is pretty popular: Simpson ALH4240 vs Simpson PS4240.

Price comparison

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 cheap side of the price range.

It can therefore be a really good buy if you're looking to acquire a budget pressure washer.

The bottom line

STRENGTHS:
  • Inexpensive
  • Triplex pump
  • Honda engine
  • Designed to be stable
  • Aluminum frame
  • Good range of nozzles included
  • Onboard storage
  • Several security features
  • CARB-compliant
  • 10 year (limited) warranty
  • High PSI for the price
  • High GPM for the price
  • High CU for the price
WEAKNESSES:
  • No soap tank

Do you own the Simpson ALH4240 and agree (or disagree) with these strengths and weaknesses?

Let us know and write your own review.

Features and Specifications

General
FuelGas-Powered
HandlingWheelbarrow
WaterCold (100°F max.)
PSI4200
GPM4
Cleaning Units16800
Engine389 cc 11.7 HP Honda GX390 OHV 4-stroke
PumpCAT Triplex
SeriesAluminum
Other model numbers60688
Features
FrameAluminum
Soap injectionVia siphon hose
Nozzles0°, 15°, 25°, 40°, Soap
Quick connect nozzlesYes
Onboard storageYes
Hose50 ft, ⌀3/8
Hose storageHooks
Misc
Dimensions
(L x W x H)
Approx. 38 x 23.5 x 26 in
Weight133 lbs
Pressure controlDial-N-Wash® + unloader valve
Wheels2 wheels, ⌀13", pneumatic
Included accessoriesOil, steel wand, spray gun, high pressure hose, soap hose, 5 nozzles, Dial-N-Wash® pressure regulator
SecurityLow oil, trigger lock and thermal relief valve
EmissionsCARB, EPA
Warranty10 years

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.

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About Simpson

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.

Warranty Information

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.

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