How to Clean Your Car’s Engine

Easy to overlook and difficult to clean, engines often go neglected and most people don’t bother to clean them regularly. But by making an effort to wash beneath the bonnet every so often, your car’s engine will stay looking and working at its best for longer – which could help its resale value when it’s time to trade in.

A lot of drivers worry that cleaning the engine bay will damage the equipment and let moisture in. But as long as you take precautions and use the right tools and products, you’ll have an engine that looks as good as the day you bought it – and continues to perform well, too.

In this guide, we look at how to clean your car’s engine safely, covering the tools you’ll need, safety tips and precautions, and step-by-step guidance on achieving a gleaming engine.

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Cleaning A Car Engine

What You’ll Need

You don’t need anything too specialist to get your engine clean. Here, we list the tools and products that will make it easy to clean all those nooks and crannies beneath the bonnet.


  • Plastic food bags or cling film – Useful to protect the electrics around the engine, so you can clean with confidence.
  • Quality spray cleaner – You’ll need a good quality trigger-action spray cleaner or engine degreaser to remove dirt, oil and residue.
  • Stiff cleaning brush – Get a brush with stiff bristles so you can give things a good scrub. A wheel cleaning brush works well and allows you to get at those hard-to-reach areas.
  • Hose – For rinsing the engine, you’ll need a hose. Using a pressure washer for this job can be difficult because if you can’t adjust the pressure, you’ll need to stand far enough back so that the force doesn’t cause any damage to connections. Therefore we’d recommend a hose.
  • Microfibre towel – For drying.


  • Engine Enamel – Engine looking a little tired, even after cleaning? A good quality engine enamel will restore its finish and add a protective coating. Simply spray on for a durable finish and protection up to 800°C. Make sure you choose the enamel colour and finish that’s right for your type of engine.
  • Black Plastic Trim Restorer – Most modern engines have black plastic covers, and these can start to look tired with age. Restore these to their original shiny black finish with a plastic trim restorer.

Ways To Clean A Car Engine

Safety Tips and Precautions

Before you start cleaning, there are a few things to do that will help you clean up without worrying about damaging any components, while getting the best results. Take a look at our essential safety tips and precautions for engine cleaning below.

Cover Electrical Components

You need to cover electrical connections to make sure no water and moisture can get into them and cause problems. Food bags work best for this, though you may get away with cling film for smaller areas like wires and cables. Use elastic bands to hold the food bags or plastic wrap in place as you clean to ensure a tight seal against water and cleaning solution.

Some of the key areas you’ll want to cover and protect include alarm systems and wiring, the battery housing, and any exposed cables which lead away from the battery. Basically, wherever there’s an electrical connection under the bonnet, it’s best to cover it.

Don’t Try Cleaning a Hot Engine

For obvious safety reasons, you should never start cleaning an engine straight after a drive or when it’s been running for a while, as you could end up burning yourself either through direct contact with hot parts or through steam.

However, it’s a good idea to clean when the engine is still slightly warm, rather than completely cool. Why? Dirt and grime will be looser when the engine’s warm, making them easier to remove when you apply the cleaner.

And that’s it – now you’re ready to start cleaning.

How to Clean an Engine in 5 Easy Steps

Making sure that all the electrics are covered, and the engine is cool enough to work with, follow the simple steps below for a clean and shiny engine bay.

Step 1: Apply the Cleaning Spray and Leave it to Sit

Working methodically from one side of the engine bay to the other, apply the spray cleaner and make sure you get into all the corners and nooks and crannies – we recommend working bottom up as well to bring the dirt upwards. Try to spray the cleaner on evenly without oversaturating; you’re looking for an even coating on all exposed parts of the engine.

Once you’re happy that all areas have been sprayed, leave the cleaner to sit for a couple of minutes. This will soften any dirt and grime, making it easier to scrub away when it’s time to start brushing. Make sure you’re careful not to get the cleaner on your paintwork!

Step 2: Agitate Dirt and Grime with a Stiff Brush

After a few minutes, it’s time to go at the engine with your stiff wheel cleaning brush. Make sure you work methodically and clean every component, using the brush to reach into those awkward areas. Use a twisting motion to really agitate dirt and grime and loosen it up, but be careful around areas where you’ve covered electrical components.

Step 3: Rinse the Engine

When you’ve scrubbed down the entire engine and got into all those hard-to-reach areas, it’s time to rinse things off. A simple hosepipe works best for this, as you’ve already done all the hard work with the brush, so not a lot of pressure is needed. Rinse off any residual dirt and cleaner, leaving the engine clean and ready for drying.

Step 4 – Dry the Engine

Using a microfibre cloth, dry off the areas of the engine you can easily reach. This will ensure a shiny, streak-free finish, but don’t worry if you can’t get to every area with the towel, as these can be left to air dry.

Step 5 – Remove the Plastic Coverings

With the engine looking good as new, don’t forget to remove the protective coverings from the electrical components before closing the bonnet.

And there you have it – 5 steps for a clean and tidy engine. At Redex, we help drivers maintain the life of their car’s engine with our innovative fuel additives and system cleaners. For more information, visit our homepage today.