Building A Gas-Powered Pressure Washer

While you can always buy the tools you need, there’s something to be said for the satisfaction gained when you pick up a tool you built yourself. [Workshop From Scratch] has built a following out of building his own gear, the latest of which involved putting together a gas-powered pressure washer.

The key to the build was to keep things completely self-contained. All the consumables – water, soap, and wax – are kept onboard the washer to avoid having to run hoses and so on. A small gas engine is the heart of the build, hooked up to a high-pressure water pump. It even comes complete with a starter motor, making it a certified luxury garden tool. It’s also hooked up to two tanks holding cleaning solutions for car washing purposes, which feed into the pump via an auxiliary port for mixing. It’s all assembled on a custom steel frame welded together from rectangular hollow sections.

It’s a build that demonstrates how you can use your skills to build tools that suit your workflow, rather than just putting up with whatever is available off-the-shelf. We’ve seen his work before, too – building other tools like this motorised plasma cutter. Video after the break.

23 thoughts on “Building A Gas-Powered Pressure Washer

  1. Nice job. Not cheap. Definitely do not want one. I’d never get any sleep since my wife would have me washing everything in and around the house. Now just need a way to refine your own gas or use some other fuel. Ethanol in gasoline is death to small engines.

    1. Ethanol myth is a myth… if you put it in your gunky unmaintained piece of crap and it mobilises the gum enough to block the jets, you blame the ethanol instead of your lack of previous maintenance, which was probably gonna bit you in the ass real soon anyway.

      1. The ethanol they add to fuels isn’t pure, but contains methanol, acetone, etc. since they don’t have to make it drinkable. These are harsh on the gaskets and other stuff, but methanol and ethanol also directly corrode aluminum, and they’re hygroscopic so when you leave the fuel sitting around it has a tendency to collect water which also corrodes the engine parts. The very least you have to do if you’re running your lawnmower on E85 is to empty it completely of fuel after use and run a cup of real gasoline through it to replace whatever is left in the lines and pumps.

        New engines that are designed for flex-fuel operation have their aluminum parts nickel coated, which inhibits the ethanol corrosion, while older engines and cheap small engines with plain aluminum castings slowly disappear into white dust.

        1. More precisely, ethanol and methanol corrosion with aluminum is accelerated in the absence of water – and it’s called “dry corrosion”. The reason given: “In an environment of very low water content the passive surface oxide is not able to re-passivate and corrosion starts. Corrosion starts at weak points and pits are formed.”

          This condition can occur because the ethanol fuel does pick up water from the air over time, so it is regulated to be delivered at the pump below 0.3% – 0.5% water content to keep stations from selling stale fuel and for other quality control reasons, which coincidentally makes it corrosive to engines made out of aluminum.

          Ironically, the fresher the fuel, the more damage it does. Of course throwing a cup of water into your gas tank isn’t exactly going to stop the corrosion either, although it does slow it down.

        2. The chemical reaction goes:

          3C2H5OH + Al → Al(C2H5O)3+ 3/2H2
          Al(C2H5O)3+ 3H2O → Al(OH)3+ 3C2H5OH
          2Al(C2H5O)3→ Al2O3+ 6C2H4+ 3H2O

          So the reaction needs a little bit of water to proceed, but once it’s going it is consuming the water it makes, and generates hydrogen and ethylene gas, and finely powdered alumina, which is the white stuff you see inside the carburetors and fuel pumps of small engines run on ethanol fuel.

          1. Sorry, I live in the world where my aluminum parts already have an oxide coating and therefore have no chemically active aluminium to react. I also find no white stuff in my small engines.

        3. The ethanol is required to be “De-natured” because the feds don’t want you to drink it without being taxed. Ethanol is 30% oxygen and has a lower fuel energy density.
          The Feds mandated the ethanol addition, even though they really don’t understand why.
          From a .GOV Site:
          “A gallon of ethanol contains less energy than a gallon of gasoline, resulting in lower fuel economy when operating your vehicle. The impact to fuel economy varies depending on the energy difference in the blend used. For example, E85 that contains 83% ethanol content has about 27% less energy per gallon than gasoline (the impact to fuel economy lessens as ethanol content decreases). Engines in gasoline vehicles, including flexible-fuel vehicles (FFVs), are optimized for gasoline. If they were optimized to run on higher ethanol blends, fuel economy would likely increase as a result of increased engine efficiency.

          Ethanol also has a higher octane number than gasoline, which provides increased power and performance. For example, Indianapolis 500 drivers often fuel their race cars with E98 because of its high octane. ”

          Clearly, the feds want it both ways.

          Actually, INDY cars use ethanol due to the oxygen content, allowing higher compression ratios. (And cooling)
          So, lower fuel economy solves the energy problems? I don’t think so..

          1. Yeah, I’m not sold on the whole corn to ethanol thing being economically or ecologically valid. Ethanol could be viable, just not the way it’s being done. I was running two vehicles at the changeover here, one lost a couple of mpg, one gained a couple of mpg. I believe the one that gained was able to use more timing advance, whereas the one that lost had less leeway. Or the one that improved had better fuel atomisation with ethanol and/or needed a little more O2.

            Anyhoo, feds kinda get in the way of good efficiency on ethanol for retrofit, because you can’t mod your tune to make best use of the octane. Though also you can’t just twiddle a knob and get a higher compression ratio anyway, but different cam timing or profiles might give you higher effective running compression.

            But the corn to ethanol is energy intensive, so given that most vehicles lose, and the gain over inputs is slight, the best you can say is that it keeps a few thousand tons of carbon in a rotating sink.

        4. “The very least you have to do if you’re running your lawnmower on E85 is to empty it completely of fuel after use”

          I have a couple of Tecumseh engines that do a fine job of emptying their own fuel tanks after I am done using them!


      2. No, ethanol can be really bad for vintage car engines. An original fuel pump diaphragm that has been running for decades can be turned into goo with one tank, leading to fuel flowing into the crankcase and diluting the oil thus destroying the engine.

        1. Yes, you should be aware of any natural rubber parts, and other incompatible compounds and replace them in older equipment. I’ve had lawn equipment never seen ethanol though, been forgotten in a shed 20 years and the fuel lines are cracking and crumbling off. That says to me, that they were crappy lines needing regular replacement. So I’m not buying the “ethanol ate my lines” on those.

          However, again I’ll say, how many decades should you have trusted that diaphragm for? Why not replace a part that can have such drastic consequences for failure. Back before the 90s I didn’t trust a rubber part more than 5 or 10 years, belts and hoses were very regular replacement items. Then we got better compounds. Sorry but I’ll call lack of maintenance on that too really, it’s stupid to rely on a rubber part that long. It’d be stupid to put a NOS rubber part in there too, it’s age not wear on them.

    2. I once saw a hack to separate the ethanol out by deliberately mixing ethanol fuel with water and then letting it settle out for the different fractions. With enough water, the ethanol separates. Of course the separated gasoline is poor in quality because ethanol is used as an octane booster, which is the major reason why they keep adding it – to sell worse fuel.

    3. In the Southern states in the US (maybe others), it is possible to buy ethanol-free gasoline. It is labelled “Recreational Fuel”, is 90 Octane, and is ostensibly for boats. I use it for the mowers, generators, chain saws, log splitter, and power washer.

      1. I live in the midwest and there is a station down the road from that sells straight gas on one pump. As others have said it can wreak havoc on on gaskets and fuel lines, is hygroscopic and causes corrosion so i use it in my small equipment and my Ford Model A’s. Now I can leave the fuel in over the winter and not worry about it.

    1. Good question. It looks like a petrol engine but saying gas could mean anything. Propane is sometimes used as it’s inexpensive and doesn’t have issues evaporating like petrol does in the cold.

      But if we could choose a gas, air would be best. There’s plenty of air.

  2. Maintenance on pressure washers are the key to longevity.
    That’s why I got mine for free after the original owner failed to maintain his, and kicked it to the curb.
    One rebuild kit for the pump, one gasoline flush, and it was back spraying the driveway.

  3. Maintenance or replacement because of pressure washers is key to long lasting concrete or brick. Quit fracking things with all their might. A trailer that hauls hogs to market is a good use for pressure washing, not your home.

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