How To Clean A Car Engine in 6 Easy Steps

Chloe Murphy 5 minutes Published: 26/08/2021

It’s a pretty great feeling when you’ve cleaned your car inside and out, but most drivers will neglect to clean their car engine.

For those familiar with what’s under a car hood, cleaning the engine shouldn’t be much harder than the rest of the vehicle. 

Though it’s not exposed in the same way as your exterior, dirt and grime can still build up inside your engine. The dirt itself might not damage your engine, but it could disguise problems like fluid leaks, which can cause an MOT fail

Is it a good idea to wash your car engine?

Though the cleaning itself might not improve your car’s performance, cleaning your car engine will help you spot any issues. You’ll be able to check the condition of the hoses, parts, and accessory belts and remove any larger debris. 

It might seem a mammoth task, but establishing a semi-regular engine cleaning routine will make it easier and faster every time. Regular cleaning will help you pick up on and resolve any problems. particularly if you live in a climate where snow, salt, and grit are likely to work their way into the engine.

Is it safe to spray your engine with water?

You can spray your engine with water, but it’s important to do so very carefully. Spraying water onto hot parts could cause them to crack or warp, and you could easily burn yourself. 

There’s also the potential for water to get into electrical connections and components. Even the smallest amounts of water can cause substantial problems, so it’s ideal to cover up any electrical parts with plastic bags - but please do make sure it’s all cool first!

What's the best way to clean a car engine?

Following our simple steps, you won’t have to stress over cleaning your car engine wrong or causing damage.

Before you get started, it helps to have the following tools and equipment:

  • Air compressor
  • Flashlight
  • Engine cleaner or degreaser 
  • Plastic bags
  • Gloves
  • Pressure washer/hose (Optional)

1. Plan when you’re going to clean

Picking the right day to clean your car engine can help to speed up the process of drying the engine components after you clean. You’ll also want to choose a time when your car is likely to be cool. Grease and dirt may be removed easier when it’s engine is still slightly warm, but it’s vital not to spray engine cleaners on hot parts.

If you’ve been driving or running the engine, wait approximately 20 minutes for it to cool down. It should be cool enough to touch, and you can test a small area before getting started.

2. Remove plastic parts

Take off any plastic covers as these can be cleaned separately, and will help avoid getting water in the engine. You should also remove the negative terminal from the battery, or simply remove the battery entirely.

3. Cover electrical parts

Using plastic bags, cover up any electrical parts. If you’re well practised in cleaning your engine, you can skip this step, however you take the risk of damaging your electrical components. You’ll have to be more precise with your cleaning, and it could end up taking longer.

4. Degrease and clean

Cover your engine with your chosen degreaser or engine cleaner, thoroughly saturating areas with more build up. Leave to sit depending on your product’s directions, then use a detailing brush to scrub away the grime. Apply more product to stubborn dirt if necessary.

5. Wipe down and rinse

If you’re feeling particularly cautious about getting your engine wet, you can wipe it down first. With a damp microfibre cloth, just go over all the areas that you sprayed cleaner onto. However you want to be sure all of the product is rinsed off, so this could be time consuming. 

Alternatively, use a pressure washer or hose on a very light spray setting.

6. Dry the engine

Using a clean, microfibre towel, wipe down the engine to dry off any excess water. This is where it comes in handy to choose a warm day, as it will help the engine dry off naturally.

Other Car Engine Checks

Since you’re under the bonnet anyway, you may as well take the opportunity to check up on other aspects of your engine. 

1. Check the engine coolant

A simple check, just take a look at your engine coolant. If the liquid looks murky or sludgy, it’s probably been contaminated by an oil leak. As the engine coolant keeps your car from overheating, it’s important for it to be in working order.

If the liquid itself looks fine, just check that it’s at the right level and top it up if required.

2. Get an oil change

If you discover dirty oil during your car engine cleaning, it’s probably about time to get an oil change. Dirty engine oil that looks thicker than normal can damage engine parts, hinder your car’s fuel economy, and even trigger a breakdown.

3. Check your fuel injectors

If you’re unfamiliar with your car parts, cleaning your car’s fuel injectors probably sounds like something to leave to the professionals. But leaving fuel injectors clogged for prolonged periods can cause your car to run poorly, reduce your fuel economy and even result in rough idling.

Fortunately you can read up on both beginner and intermediate ways of getting them clean with our guide on how to clean fuel injectors

4. Get a full engine tune-up

A full engine tune-up will ensure that your engine is not only clean, but operating to the best of its ability. This should be done anyway approximately every year, but if you’re handy with your car engine components, you can do this yourself when you clean your engine.

Whether you DIY it or go to a professional, you should check the spark plugs, hoses and belts, and the air filter.


Keeping your car engine clean is a great task to add to your car maintenance checklist. You may prefer to wait until your service, but cleaning may not be listed in what a car service includes.

Though they will check up on and fill all the fluid levels like screen wash, brake fluid and engine coolant, they won’t actually clean anything in your engine. This means it’s up to you to ensure that they’re dealing with clean components, and that they can easily spot any arising issues.

How often you should service your car depends on your mileage, climate and general car use, but it’s recommended at least once a year. If you begin to have issues, notice unusual noises, or feel it’s performing poorly, it’s better to book it in sooner rather than later!