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How to Pressure Wash Engine Bay Properly

You wash your car exterior when it gets dirty, but do you ever wash its interior? I’m talking about the engine bay. You know, it gets pretty dirty there too. Dust, dirt, oil and grime settles there over time. These things can impact the engine performance of your car.

A quick and effective way to clean your engine bay is with a pressure washer. To do this, you need to cover the car’s electrical components, spray exposed surfaces with an engine degreaser, scrub and agitate dirty areas, rinse with a pressure washer at a low pressure setting, and then let it dry. That’s it! It’s that simple.

If you’re thinking about pressure washing your engine bay just follow the basic steps I just mentioned. There’s a handful of other details that might help you along the way. So if you’re interested in those ready on.

Basic Steps

There’s five basic steps to pressure washing an engine bay properly:

  1. Cover electrical components
  2. Spray on engine degreaser
  3. Scrub dirty areas
  4. Rinse with pressure washer at a low pressure setting
  5. Let engine bay dry

Step 1: Covering electrical components

Before the actual cleaning process begins you have to cover any electrical components and cover them. Use plastic grocery bags or saran wrap to cover the spark plug, alternator, distributor cap, and alarm system and any other electrical connections. Secure these coverings with tape or rubber bands so they don’t fall off while washing.

Step 2: Spray on engine degreaser

Oil and grease are difficult to clean, even with a pressure washer. That’s why it’s a good idea to spray on engine degreaser to loosen up these dirty spots before washing. It’ll make rinsing with pressurized water a lot easier and quicker.

Choose a cleaning solution that’s specifically made for engines. Be careful to pick one that’s water based and biodegradable. You don’t want a cleaning solution that’s corrosive to the metals and plastics in the engine bay.

Spray on a layer of the degreaser that’s enough to cover the areas with dirty buildup. No need to saturate surfaces. Be sure to get into all the small crevices. Then give it a couple of minutes to do its work.

Step 3: Scrub dirty areas

After the engine degreaser has done its job of loosening the oil and grease, you’ll need to scrub down the engine bay with a stiff brush. Some people get by with a toothbrush. The brush will further mix the degreaser in with the dirty areas and agitate the stains so that they’ll come off easily. 

Copyright article owner is for this article. This post was first published on September 10, 2019.

Step 4: Rinse with pressure washer

Whether you’re using an electric or gas pressure washer, you need to spray using low water pressure. Applying too much water pressure can damage parts of your engine. Two pressure washer configurations to pay attention to are the pressure washer’s PSI and nozzle.

PSI selection

PSI stands for pounds-force per square inch. In layman’s terms, this metric describes how powerful the water pressure is. So a washer with a high PSI selection can blast out a highly pressurized stream of water, as opposed to a washer with a low PSI selection. 

A PSI setting between 1,000 and 2,000 PSI is a safe choice for pressure washing engines. I’d go with something right in the middle like around 1,500 PSI.

Nozzle choice

Pressure washer nozzles also play a role in regulating water pressure. Some nozzles have large orifices that put out wide spray patterns and low water pressure. Nozzles that have small orifices force water out of small openings. They’re water stream is more concentrated and thus more pressurized. Because their orifices are small, these nozzles produce narrow spray patterns. 

When pressure washing an engine use a white or a green nozzle. Start with the white nozzle. It produces a 45 degree spray pattern and sprays out relatively moderate levels of water pressure. If you feel the white nozzle is lacking, switch to the green nozzle. It produces a 25 degree spray pattern and sprays out at slightly more water pressure than the white nozzle. I wouldn’t go further than that, like with a yellow nozzle. And I would never use a red 0 degree nozzle.

I would say that for this job an electric pressure washer is sufficient. Gas powered washers are expensive and too powerful for this kind of job. Plus, there’s more maintenance involved with gas washers.


As for the technique you should use when pressure washing an engine I would say there really isn’t one. Just use common sense. Don’t spray too close to any particular area and avoid electrical components, even though they’re covered. Position the end of the wand at least a foot away from any surface when spraying.

Let engine dry

Take off the plastic coverings and use some towels and wipe down the engine. Old shirts, rags, and microfiber towels are some suggestions. Some people use compressed air to dry hard to reach places. You don’t have to get it completely dry. Just dry enough so that when the next time you drive out all moisture isn’t still there and picking up dust while on the road.

Soap Application

After degreasing and rinsing, some people like to throw in another step with soap application. This is fine, if you want to get a really good deep clean. You can use a car wash and wax soap cleaner or some people use dish soap. Whatever works. Then you would rinse off the soap like you did with the pressure washer.

Additional Detailing

Want that extra shine after all that work? Consider dressing up your engine with protectants for your plastics and metals. There are different sprays you can get. Just apply and wipe down with a microfiber towel. You’re plastics will have an extra pop and your metals and added sheen.

Is it Risky?

I’m sure this question has come to the minds of those who’ve never done it before. Engines are expensive and complicated. You don’t want to mess them up. Water, especially pressurized water can cause serious damage.

There’s risk to everything and pressure washing can be risky if not done properly. Lucky for us, there’s only a few safety measures that we should keep in mind to prevent injury to us and damage to the engine. There’s really nothing to be scared of.

Technology has advanced quite a bit, and engines of today are nothing like they were a decade ago. For example, car engines today have more plastic coverings and water resistant connections than those of years ago. That doesn’t mean you don’t take heed and cover those components that are exposed, but there’s certainly less to be worried about.

Safety Tips

Keep in mind these safety tips as you’re pressure washing your car’s engine bay.

  • Wear protective coverings. Protect your eyes with safety goggles and your feet with closed toe shoes.
  • Avoid pressure washing a hot engine bay. You can burn yourself.
  • Disconnect your car’s battery terminals and cover with a plastic bag.

Final Thoughts

We don’t wash our engine bays because either it’s scary or because we don’t think about it. Truth of the matter is, engines get dirty. Dust settles on it. Grease and oil spill out. Dirt cakes over it. Whatever the reason, they need to be cleaned in order to maintain proper engine performance.

ReadyToDIY is the owner of this article. This post was published on September 10, 2019.

The task might seem more like a labor intensive chore involving lots of hand scrubbing. That doesn’t have to be the case. Let pressurized water lift and wash away the dirty areas of your engine. It’s quick and easy.