How To Wash Car Engine Safely


The engine bay is often overlooked while washing cars. Many people like washing their cars regularly but they don’t pay attention to what’s under the hood. A car can look nice and shiny but be a disaster under the hood. The engine bay is not directly exposed to dirt but some dirt particles manage to get through. So, cleaning the engine bay once in a while is a good practice. Anything that includes the engine can be scary but we are here to learn. Here is a guide on how to clean the engine bay of your car.

  1. Choose a sunny day and cool your engine.
  2. Remove the negative terminal of the battery.
  3. Cover electrical components with plastic.
  4. Add degreaser
  5. Scrub with a microfiber cloth
  6. Rinse with a water hose.
  7. Dry

As you can see, it’s not that complicated. Cleaning the engine bay may sound scary but it’s nothing dangerous if you are being careful. A thorough step-by-step guide follows.

Pick The Day

Pick The Day

First of all, you can’t just clean your engine bay any day you want. Cold days, especially during the winter are a big no. You can’t really damage the engine by cleaning the bay but you want the water to dry as fast as possible. That’s why a sunny warm day is the best time possible for washing the bay. This allows for the accumulated moisture to dry completely and quickly.

This is something you plan ahead, not a spur of the moment. So, follow the weather forecast, pick a sunny day. Also, make sure you are doing this during the daylight hours, not during the nighttime.

Also, choose a well-ventilated area. Make sure that you have plenty of working room. You don’t want dirt to get into the bay while you are scrubbing. One more thing, the engine should be cooled down. You shouldn’t wash the bay with a warmed-up engine. Warm engines and cold water do not mix well, you can damage the engine if you are doing this with a hot engine.

Remove The Negative Terminal

Start by removing the negative terminal of the car battery. This is a must. The electrical components are the only thing that can be damaged while you are washing the car. We all know what happens when water comes in contact with a live current. You can easily avoid all of this by removing the negative terminal. This will make sure that there’s no current through the electrical components.

Now, if this scared you, then just remove the entire battery. By doing this you are completely eliminating any possibilities of damaging electrical components. Removing the battery is relatively easy. Just remove the terminals, then unscrew the straps that are keeping the battery in place. If you are having trouble with it, find a video tutorial for removing a battery, look for your car model though.

Optional: Protect Sensitive Components With Plastic Bags

Even if you took out the battery terminals, some components are still exposed to damage. The ignition wires, the control unit, etc… all can be damaged if they come in contact with excess water. A droplet here and there probably won’t do anything, but something will get messed up if you spray too much water. You can protect these sensitive parts by covering them with plastic bags. The reason this is optional is that if you are careful, this is not really necessary.

So, if you think that you can be extra careful while scrubbing and rinsing, then don’t bother covering the parts. But if you want to be careful, cover the electrical components and the air intake if it’s open to water penetration.

Apply A Degreaser Product

Apply A Degreaser Product

I have seen people using all kinds of degreaser products. Household items are also okay. But I must recommend an Engine Degreaser Spray, something like WD-40. You can also go with something natural. If you are up for buying a specific product, I recommend that you go with an engine cleaner. With a product like this, you can’t go wrong. More so, it’s specifically made for engines, so it will do wonders.

Apply the spray throughout the engine compartments. You can apply the spray freely here, don’t be scared. You can’t really damage anything with the degreaser. Chances are, there will be a lot of grime in the bay, especially if you have a really dirty engine bay.

Scrub With A Microfiber Towel

Once you are done with the degreaser, you need to start scrubbing. My advice is, to start wiping in one direction. Get that surface dirt out of the way. Do not scrub or make circles right away. Just wipe. If your bay is not that dirty, after the wiping, it will look good enough. It’s okay to scrub with the towel but this is best done once you get rid of the surface dirt. Once you are left with only the hard-to-get rid of dirt, you can start scrubbing. This way, you won’t have to reapply the degreaser to the clean parts, just the really dirty parts.

First, try scrubbing with the microfiber towel. If this is not effective, try a bristled cleaning brush. Don’t use those brushes with wires. You want something softer that won’t scratch the entire engine bay. Feel free to apply the degreaser several times on the dirt that you can’t get rid of.

Rinse With Water

Rinse With Water

Now, you have to get rid of the degreaser. You will do that by spraying the engine compartments with a water hose. Some people recommend a pressure washer here but I don’t agree. It’s okay if the washer has a low-pressure setting. But this low-pressure differs from washer to washer. So, what you may think is okay, may not be low enough. Pressure washers can be too powerful for the engine. A water hose is the safest way here.

Carefully, and thoroughly, rinse the entire engine bay. Do not spray over electrical components though. Water will splash, of course, but the real danger is with direct contact with the sprayed water. Go easy on parts that are not directly exposed to sunlight. These will take more time to dry, so excess water won’t do any good.

Wash Again If Needed

If you are not satisfied with how your engine is looking, you can redo all of these steps. Once you are satisfied with how clean your engine is, you can move on. Do not wipe with the same dirty towels though. Consider using a stronger degreaser.

Let The Engine Bay Dry

The sun will do its job but you will have to help a bit. Get microfiber cloths and wipe away the leftover water. Wipe only on parts that you can access. Don’t go out of your way to wipe each nook and cranny. You can use compressed air but make sure it’s set on low. Do not start your car just yet though, allow for at least an hour to pass, just to make sure.

Reassemble Everything

Reassemble Everything

You are done, all that is left to do is put the negative terminal back in. Remove the plastic bags that you used to cover the sensitive parts. If your engine is dry, and you put everything back together, you are ready to drive.

Additional Cleaning Tips

  • Get as many microfiber cloths as you can. It’s best to wipe with a clean towel. Dirty towels will only make your job harder, dirt particles will stick to the bay again. This is a must if you have never cleaned the engine bay before.
  • If you don’t have a water hose nor a pressure washer, consider going to a self-serve car wash. You can find one of these things there.
  • You can add some warm water to the stuck dirt. Don’t just scrub too hard, it’s easier to get rid of loose dirt.
  • If you are a messy worker, use rubber gloves. Also, use safety glasses while applying the degreaser and while rinsing.
  • Use rubber bands to make sure that the plastic covers do not fall off.
  • You can liven up the metal surfaces of the engine compartments with wax.
  • Use a non-corrosive product to avoid damaging the rubber components.
  • Use an eco-friendly product to make sure the engine components stay safe.

Related Questions And Other FAQs

Can You Clean Your Engine With WD-40

Yes, you can use WD-40 to clean your engine. WD-40 is an engine degreaser spray, so it won’t cause any damage. Apply the spray and leave it on for 3-5 minutes before scrubbing.

Is It Safe To Spray Your Engine With Water

It depends on what you will be spraying and what you will be using to spray. Spraying the engine with water is okay as long as you avoid directly spraying into electrical components. It’s best to spray with a water hose, if you are using a power washer, set it on low.

Can I Wash My Engine While It’s Hot

Absolutely not. If a hot engine comes in contact with cold water, a process called rapid contraction happens.

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