Simpson PS4240S Honda GX390 Review: Is It Worth Buying?

Overview

I've been running a small pressure washing side business for eight years. I've owned or rented over a dozen machines in that time. When I saw the Simpson PS4240S with the Honda GX390 engine, I expected a workhorse. At 4200 PSI and 4 GPM, it sits right at the edge of what a homeowner can reasonably move around and what a pro needs for daily work. The price tag is $1199. That's not cheap. But I bought one anyway because I needed something that could handle heavy-duty cleaning without breaking down on me in the middle of a job.

Who is this for? Honestly, it's for people who are tired of cheap consumer-grade washers that die after two seasons. It's for the guy who wants to clean his concrete driveway, his barn siding, and maybe help a neighbor with their fence. It's not for someone who just wants to spray off their car once a year. That person should buy something lighter and cheaper. This machine is heavy, it's loud, and it takes up real space in your garage.

I did not get this as a review unit. I paid for it. So this is not some sponsored fluff piece. This is me telling you what I found after using it for three months on real jobs and around my own property.

Key Features

Let's start with what stands out on paper:

• Honda GX390 engine 鈥?This is the big deal. The GX series is the gold standard for small engines. It's a 389cc, 13-horsepower commercial engine. Not the cheap Honda GC series found on cheaper machines.
• 4200 PSI and 4.0 GPM 鈥?That's solid flow for a machine in this price range. PSI is high, but GPM is what actually moves dirt. 4 GPM is where cleaning gets fast.
• CAT 3CP pump 鈥?This is a triplex plunger pump. It's oil-bathed, not one of those sealed grease-packed units that die when a seal goes. You can rebuild this pump.
• Belt-drive system 鈥?The engine mounts to a frame, not directly to the pump. A belt connects them. This reduces vibration and lets the pump spin at the right speed. It also means you can replace the belt instead of scrapping the whole machine if something goes wrong.
• Weight: 124 lbs 鈥?This is a pig. No two ways about it.
• Wheel kit with 16-inch tires 鈥?Big pneumatic tires. They roll over gravel and uneven ground better than the little plastic wheels on cheaper machines.

The gun and wand that come with it are decent. The spray tips are color-coded standard 5-pack (0, 15, 25, 40 degree, plus soap). Nothing fancy, but they work. The hose is 50 feet of 3/8-inch wire-braided rubber. That's actually a good hose. Most machines give you 1/4-inch hose that kinks constantly. This one doesn't.

Performance

I took this machine to a job I'd been dreading. A client had a 100-foot concrete driveway that hadn't been cleaned in seven years. Oil stains, moss growing in the cracks, tire marks, the works. I had two hours to get it done.

I set up the machine with the 15-degree tip and went to work. The first thing I noticed was the trigger response. No lag. You pull that trigger, the pressure is there immediately. My old Karcher K5 had a noticeable delay while the unloader valve adjusted. This Simpson didn't do that. It hit hard right away.

The drive took me 35 minutes flat. That's using the Simpson surface cleaner (sold separately, by the way 鈥?the machine doesn't come with one). With the 4 GPM flow, the surface cleaner floated properly and didn't bog down. I've used a 3 GPM machine with that same surface cleaner before, and it's slow and stuttery. This just rolled along and left clean concrete behind me.

I switched to the car wash later that week. Bad idea. This thing is too powerful for most car paint. Even with the 40-degree tip and the pressure turned down at the unloader, it felt risky. I used the soap nozzle and a foam cannon, and it actually did okay for rinsing. But I'd recommend buying a separate, lower-pressure machine for vehicle washing. Or use this one with extreme caution.

Wood deck? I tried it on a pressure-treated deck that was gray and dirty. I hit it with the 40-degree tip held far back, and it cleaned it fine. But the temptation to get closer and go faster is real. You will gouge wood with this machine if you're not careful. Keep the wand moving and don't stop in one spot.

Siding cleaning was a breeze. The long hose let me work around the house without dragging the machine constantly. The 4 GPM meant I could wet down a section, apply soap, let it dwell, and rinse it off without waiting for the spray to crawl up the wall. The machine didn't stutter or lose pressure even when pulling from a garden hose that was 75 feet long. That's impressive.

Build Quality

This is where the Simpson PS4240S either wins or loses, depending on what you care about.

The Honda GX390 engine is a tank. It starts on the second pull cold, first pull warm. The choke lever is right there, easy to reach. The oil fill is easy to access. The fuel shutoff valve is metal, not plastic. This engine will outlast the frame if you maintain it.

The CAT 3CP pump feels solid. It has an oil sight glass so you can check the level. There's a thermal relief valve that protects against overheating if you idle too long. The pump is bolted to a heavy steel bracket. Nothing wobbles.

But the frame. The frame is where I have complaints. It's tubular steel, and it's decently welded, but the paint is thin. I've already got rust spots where the paint chipped from rocks. That's cosmetic, but it bothers me on a $1200 machine. I fixed it by spraying on some black Rust-Oleum, but I shouldn't have to do that immediately.

The wheels are big and roll well, but the axle is not greasable. The wheel bearings are sealed and will eventually wear out. I grease the axle stubs anyway before assembly on any machine I buy, but the manual doesn't mention this.

The handle is a two-piece design that bolts together. It's fine. It works. But it's not as solid as the one-piece welded handles on the $3000 machines. It wobbles slightly when you push it over rough ground. It won't break, but it feels a little cheap.

The biggest annoyance I found was the quick-connect couplers on the hose. They leaked. Out of the box, one of them dripped water at the gun connection. I replaced both couplers with high-flow brass units from the hardware store for $12. Problem solved. But come on, Simpson. For this price, include couplers that don't drip.

The instructions are terrible. The manual is generic and shows a different model number in several diagrams. The oil for the pump is not included. The engine oil is included in a little bottle, but the pump needs its own oil (ISO 68, by the way). They don't tell you that clearly. I realized it after I had already filled the engine and was wondering why the pump looked dry. That's a rookie mistake from the manufacturer.

Pros & Cons

Pros:

• Honda GX390 engine starts easy, runs smooth, will last for years.
• CAT pump is rebuildable and high quality.
• 4 GPM flow rate is legit. Cleans fast.
• 50-foot rubber hose is thick and doesn't kink.
• Belt drive keeps vibration down and pump speed correct.
• Big wheels roll well over obstacles.

Cons:

• Weight. 124 lbs empty. With fuel and hose, it's over 130. Loading it into a truck bed alone is rough.
• Frame paint is cheap. Rusts fast.
• Wobbly handle. Functional but not confidence-inspiring.
• Quick-connect couplers leaked out of the box on my unit.
• No surface cleaner included. That's another $150 to $300 you need to spend.
• Too powerful for gentle tasks like car washing.
• Loud. The GX390 is not quiet. Ear protection required.
• Pump oil not included and not mentioned clearly in manual.

Value for Money

$1199 is a fair price for what you get. But let's be real about what you're paying for. You're paying for the Honda engine and the CAT pump. Those two components alone are worth $700-$800 if you bought them separately. The rest of the machine 鈥?the frame, hose, gun, wheels 鈥?is basically a delivery system for those two parts.

Compare this to a machine like the Generac 6921 that's $999 with 4200 PSI and 4 GPM, but has a Honda GX390 clone engine and a Chinese pump. That's a difference of $200. The Generac will work fine for a homeowner who runs it twice a year. But if you're using it every week, the Simpson with the real Honda and CAT pump will still be running when the Generac is on Craigslist for parts.

On the other end, you have the B.E. Belle Group S7-50 which runs about $1800. It has a Honda GX390 and a General Pump. The build quality is undeniably better. The frame is thicker, the handle is welded, the wheels have grease fittings. If you're doing this full time professionally, buy the B.E. Belle. If you're a serious homeowner or part-timer, the Simpson is fine. The $600 savings is real money.

My old Karcher K5 cost me $450 and lasted three years before the pump seal failed. Could I fix it? Sure, but the parts were nearly as much as a new machine. This Simpson should last five to ten years if I maintain it. Per year, that's $120 to $240. That's cheap for reliable cleaning power.

Verdict

Buy this if: You need a pressure washer that can handle heavy work without breaking. You maintain your equipment. You want the peace of mind of a Honda GX390 engine and a rebuildable pump. You're willing to spend $1200 and then another $150-$300 on accessories like a surface cleaner. You have a way to move a 130-pound machine around. You're cleaning concrete, brick, stone, siding, fences, and heavy-duty grime.

Skip this if: You just want to wash your car and rinse off your patio furniture. You don't want to deal with a heavy machine that requires oil changes and pump maintenance. You're on a tight budget 鈥?there are perfectly fine $400 machines for light work. You don't need 4 GPM flow and 4200 PSI pressure. You want something that rolls silently and doesn't shake your hands numb 鈥?this is a loud, vibrating machine.

I'll be honest. I was disappointed by the cheap couplers and the thin frame paint. Those are quality-control issues that shouldn't happen at this price. But the engine and pump are so good that I'm willing to overlook them. I'll repaint the frame myself. I already replaced the couplers. Once I did those small fixes, the machine is exactly what I needed.

Would I buy it again? Yes. But I'd buy it knowing I had a couple hours of small upgrades and fixes ahead of me. If Simpson spent another $20 on the machine to fix those issues, I'd be raving about it. As it stands, I give it a qualified recommendation. It's a 7.5 out of 10. Great internals, cheap finishing touches. If you're handy, you'll love it. If you want everything perfect out of the box, spend more money elsewhere.