In reading your blog I’ve seen people mention pressure washers but not much else about them. I drive an SUV, which tends to get pretty dirty (especially the body areas behind the tires) and a pressure washer seems to remove the kicked-up debris better than a hose. Are pressure washers safe to use on paint, as long as you keep the nozzle a certain distance away? For car washing I always use the widest fan nozzle. Is it better to use a regular hose? Do pressure washers strip sealant/waxes? What do you recommend? I want to do a thorough job without damaging the finish. Thanks. -J

J,
One of the best tools for washing your vehicle is, without a doubt, a pressure washer. Its power pushes water under grime and soil to remove these things much faster and more effective, and without mechanical agitation which lowers the risk for inducing swirls in paint. It also permits the use of other tools such as foam guns or foam canons. But with power comes risk, and one must be prepared for the responsibility of harnessing the power or the pressure washer. In this Ask-A-Pro article, we will discuss what to look and look out for when shopping for a pressure washer, and some recommendations on its use.

AutoLavish Tips on Selecting the right unit

Your selection of pressure washer will be the most difficult aspect of using it. There are so many choices out there and all have advantages over the next unit. A couple important questions you’ll need to answer for yourself: what are your requirements; will it serve double duty as a pressure washer to use around the house and your car, and are you working away from a power source?

If your pressure washer will be used on more than your car or you’ll be working away from an accessible power source, an engine powered pressure washer with a good set of nozzles to fan out the stream might be a good buy. If not, an electric pressure washer has plenty of power for washing any vehicle and is much more safe and easy to use, not to mention more economical. We use electric pressure washers for all our detailing.

Be aware that even an electric pressure washer can be too powerful. I chipped the inside of a door channel on my BMW with too much pressure not long ago. On some cars and/or surfaces you should not use a pressure washer and will need to use a normal hose.

Always pull the trigger with the wand pointing away from the car and away from people, pets, plants, etc. to make sure the fan setting is appropriate before spraying it on the vehicle. I have rarely used the washer at full stream, and will always fan out the stream somewhat. A stream 2 inches wide is powerful, but much less harmful than a stream half the width. Use tighter streams for wheels and brakes, use slightly wider streams for fenders, rocker panels,  and metal bumpers. Use a wider stream for stubborn bugs and for rinsing off shampoo. Notice the fan width in the following pictures. Even for dirty wheels we do not use the full stream. Once you use your pressure washer a few times, you will get a better feel for it, and will be able to proceed more aggressively and faster while still feeling in control. Practice is the only way to get to know your machine. Start out with a vehicle other than your most prized possession. Also, the older the car is, the more delicate it can be. Keep it in mind. Do some research and see who is using the pressure washer for what jobs before going crazy with the thing. Here are a few pictures that show a few different fans being used based on the panel/surface:

In the following picture, I am removing polish residue from the hood-to-fender crevice with high pressure. Notice I keep the tighter fan farther away from the vehicle.

When looking for a pressure washer, consider the wand length. Shorter or flexible wands are great for fender liners and wheels. Longer wands are good for larger engine bays and lifted trucks. Smaller triggers/wands are lighter. The trigger/wand can be quite heavy when in use under the full power of a jet of water.

Some pressure washers have built-in soap or chemical dispensers. In our experience, they fail to deliver. Most devices will drop the internal pumping pressure as they dispense the chemical, and none offer anywhere near the foaming action you get from a foam cannon, like the awesome pictures you see pro’s post of their washes.

Some pressure washers have reels or coiled hoses. These are great for keeping the machine tidy, but can be troublesome to pull out more hose in a pinch. The coil hose will always be pulling on the machine, and could end up putting the machine into a car fender or bumper. Make sure your pressure washer has some sort of warranty. Every washer I have owned has needed replacement after a year or so of heavy usage. I have yet to require a new hose, but it is always good to find a pressure washer with readily available replacement parts. If you buy an electric machine, make sure the pressure washer is 120 Volts (assuming you are in the US). If you buy an engine-powered one, make sure it does not take special fuel you might not be able to find all the time or costly maintenance. Do read reviews of pressure washers on places like Amazon and ConsumerReports to confirm the machine you plan on purchasing is solid for your needs.

Many machines are built to be nice looking on the outside, but cheaply made on the inside (where it actually counts). In most instances, machines are a re-badged pressure washer of another brand’s machine with different plastic covers. Do not be fooled by brands. There are brands that make excellent pressure washers, and others that make excellent “other types of tools” but not good pressure washers. You get what you pay for. Purchasing from a local store makes it easier for returns or to fix problems, and can be quicker than purchasing and returning via the internet. Local places that sell them usually carry accessories too. If you’re debating on a local purchase versus an internet purchase; things like warranties, customer service, and price after shipping may be factors that sway you one way or another.

Regarding the washer specifications per se, look at flow numbers and pressure numbers. High pressure just means there is more throttling of the water flow. The higher the pressure rating, the more powerful the motor/pump should be. Once the water exists the valve in the trigger, it has no pressure, just kinetic energy. The amount of water the pump moves in a unit of time is the flow rate of the machine. So a machine that states 2000 pounds per square inch (psi) at 1.3 gallons per minute (gpm) flow rate can actually be less effective than a machine that pumps 1400 psi at 1.8 gpm. We have a variety of machines, from 1400 psi to 2000 psi. We tend to most often use the machine that is easiest to maneuver. Rarely have we had to bring out a machine with more flow. If you have a big truck or boat, you will want the higher capacity machine with a longer wand or extension. For a normal car, a smaller machine should suffice.

Less functionality-based aspects are noise levels and storability. We do a lot of mobile detailing, so we need a machine that can be stored and dragged around on its side while fitting under the trucks toneau cover. If we are working indoors or in a quiet neighborhood, we use a smaller more quiet machine. Again, the smallest tool for the job makes things easier to work around.

It is hard to say specifically how to use pressure washers in a safe manner due to the variations in machines and conditions. The most important thing we can say is USE YOUR BEST JUDGEMENT! Like any method, there are risks. First off, you can hurt yourself and people around you. Accidentally spray your hand (as to try to rinse off soap suds or soil), and you will cut into your flesh, a very painful injury. On your vehicle there are many more risks. You can break through your paint and blow off chips and chunks of paint. You can strip off undercoating and other protective coatings from the suspension, engine, and wheel wells. You can blow off emblems. You can blow off stickers and labels from engine components, wheels, etc. You can break through rusted areas, and some rusted areas are not visible until too late. You can damage plastic as the high velocity water digs into the plastic’s surface, scuffing and abrading the surface. You can get water into places you do not want water, like inside the car, inside the engine and electronics, inside the tailpipe. En fin, you get the idea. It is a powerful tool, treat it with respect.

That said, the pressure washer is very versatile for the same reasons. It can make cleaning much more efficient (efficiency is defined as the ratio between how much work+energy you put into the job versus how much you get out) and can help clean better than chemicals alone when used correctly. Although it may seem counterintuitive, pressure washer’s spray travels less than a typical garden hose and nozzle, but rinses with less water as well. This makes it great for using inside a garage (in a waterproof garage of course) or in confined areas, although the washer’s hose and cord do make it a bit tricky to move around. Notice in the following picture that there is hardly any foam/water over-spray on the surrounding areas of the vehicle. This vehicle was washed indoors while it was below freezing outside in the Michigan Winter. Something that sets AutoLavish apart is being able to serve customers year round. Our pressure washer is another tool that helps maximize the results.

The pressure washer is the best and quickest tool for cleaning chassis parts and wheel wells. It cleans crevices very well. It helps to remove bugs and tar. It is great against brake dust. Equipped with a foam cannon, a pressure washer makes applying shampoo a snap and very fun experience. From there, a combination of the right tools, products, and knowledge will allow you to achieve the best results possible.

Care for the machines is easy. Never leave detergent in the on-board canister over-night. Never leave the machine in the freezing cold, or frozen water will split the copper tubbing inside the machine (ask me how I know). Expect the machine to get beat up. It is meant to be. Don’t sweat any scratches. Keep the machine relatively clean, and make sure the handle is clean as you will be grabbing the machine to move it around while washing. When done using the machine, reel the hose or wrap it neatly, detach the hose ends if possible as to minimize the stress the hose exerts on the fixture. Wrap the power cord neatly. Detach the trigger/gun and attachments and keep in a storage bag.

We hope this helps you decide to take the plunge and purchase a pressure washer, or be able to use your existing one more effectively. Good luck, and may the suds of the foam gun always be with you.