How To Build Your Own Undercarriage Washer

Undercarriage Cleaning System

While the undercarriage is usually the dirtiest part of your car, it’s also probably the most overlooked when it comes to cleaning. After all, out of sight, out of mind. Many people even realize that they should clean their undercarriage but don’t, simply because it’s a pain. This was a problem at our detailing shop too, until we devised a clever little solution using a speed bump. Read on and we’ll show you how to make your own.

So in order to use this particular technique to clean your undercarriage you’re going to need a few tools, but trust me, it’s worth it because it’ll make your life so much easier in the long run.

Metal Water Delivery SystemSprayer NozzlesCutting Rubber BottomNotch In Rubber SpeedbumpSprayer Nozzle In SpeedbumpHere’s what you’ll need:

A pressure washer – You can find an electric pressure washer for as little as $100 online with a little research. If you want a high end one it’s going to put you back a few bills though.
A rubber speed bump – Any rubber speed bump that’s 2″-3″ thick will work.
A pressure washer extension hose – Find one that will fit your particular pressure washer.
Metal piping – Use this to funnel the water to the holes you will cut in the speed bump.
Sprayer has a huge selection of these nozzles so you can get exactly the size and degree you’d like.

Begin by fitting together your water delivery mechanism. You will need a couple of steel “T” fittings and one 90⁰ elbow so that the water will be directed upwards. Fit them about 6-8 inches apart from one another with pieces of steel piping. At the top of each of the fittings attach a sprayer nozzle. You may want to choose one that fans a bit wider (say, 65⁰) for the outermost fittings in order to make sure you hit the wheel wells and outer parts of the undercarriage. The inner fittings you can go a bit smaller (closer to 40⁰). Connect all of this to the extension hose.

Next, cut a long notch into the bottom of the speed bump. (We used a reciprocating saw, but I’m sure you’ll have something in the garage that will work fine if you don’t have one.) This will house the piping that will fit into the speed bump so that it can lay flat on the ground. Once you’ve cut that out begin to cut holes through the top of the speed bump that match up with the nozzles on the pipe.

Fit the piping into the speed bump and lay it down in your garage or driveway. Once you’ve attached it to your pressure washer you should be good to go. Position you car over the speed bump and have someone turn on your pressure washer. Slowly roll your car back and forth over the speed bump until you get full coverage. Make sure the jets are turned off while the car isn’t on top of the speed bump, otherwise they’ll shoot up in the air and soak everything nearby.

Once it’s all built it’s a really quick and convenient way to clean your undercarriage. Any questions? Comments? Let us know in the comments below!

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  • CarWash Guy

    how did u fit the steel pieces together? Welding?

    • The pipe is threaded at the end and we used threaded fittings to attach everything. The whole thing is basically just screwed together. You should be able to get everything you need at your local hardware store.

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  • Gary

    Would you have something like this for sale

    • Erica Cimaglia Vance


  • Devin

    Great idea! Did you find the 65deg. orange nozzle had a good orifice size for a pressure washer with 5 jets? There are tons of sizes on the website.

    • Ya we tried a few different sizes and combinations but we found this to be the best!

      Will @DrBeasleys:disqus

  • Jeremy D.

    Would you be able to lend a hand in finding the speed bump used for this. I’m finding a few just over 2″ tall but not sure its a rubber I can hollow out and it still be stable. As per the pic do the nozzles run length wise with the vehicle instead of width wise?

  • ed

    did you know that dultmeier charges 35.00 shipping on 5 nozzles