How to clean your engine bay

Many of us are used to washing our cars on a regular basis but cleaning the car engine bay is a less common task. Often, the only time a car bonnet is lifted is for an oil change or the occasional repair. However, if you neglect what’s under your car bonnet, chances are it’s probably become very grimy as your engine bay collects all sorts of dirt over time.

Given that a car engine is a crucial vehicle component, it’s essential to ensure that it’s kept in good condition. Keep reading to discover the advantages of cleaning your engine bay and how to keep it clean.

The benefits of cleaning your engine bay

There are a number of benefits to cleaning your engine bay as it can soon become clogged up by dirt and dust after several months, which can lead to a number of issues.

Improved performance

Keeping your engine bay clean can help improve vehicle performance. Leaves and other debris can block airflow and obstruct the engine, so it’s important to remove these hindrances as soon as possible. The grill and bumper are easily accessible, making it simple to safely remove deposits.

Properly cleaning and maintaining car battery terminals can also improve battery performance. If there is a significant build-up of debris, it can clog up components like the alternator and can cause belts to weaken if not cleaned regularly. This is particularly important for vehicles that are regularly used off-road.

Improved resale value

Even though what’s under the car bonnet is not immediately visible, it can still impact the sale price of your vehicle. A clean engine bay will let buyers know that the car has been taken care of and well maintained, which can increase its resale value. A buyer is likely to pay more for a car if they can see that hidden parts have been well maintained.


If you don’t regularly clean or look under your car bonnet, any potential issues can be overlooked. Frequently checking and cleaning your engine bay will give you peace of mind that there is nothing clogging up your under-bonnet area, particularly the drain holes around the bulkhead which can lead to water ingress through the heater vents. If there is any debris such as leaves blocking the airflow, this can be quickly removed and prevent any potential damage further down the line.

Improved visibility

Regularly cleaning your engine bay makes it easier to see what’s happening on the inside of your vehicle. Removing debris and dirt can help identify leaks and other issues, which are easier to detect and locate when the engine bay is clean.

How to clean the engine bay

Want to clean your engine bay but don’t know where to start? Before you begin, you’ll need a few supplies to be able to clean everything thoroughly. It’s important to note that if you have an electric or hybrid vehicle, you should keep the cleaning of the under-bonnet area to a professional.

Items you’ll need for cleaning your engine bay:

Make sure your engine is cool

You should only clean your car engine when it’s cool. Cleaning when the car is cool is safer and makes it easier to free any loose dirt or debris without burning your hand. Under no circumstances should you clean a hot engine. Not only could you burn yourself but putting cold water on a hot engine could also cause damage.

Protect the components

Removing the car battery can protect any electrical parts during cleaning. However, only isolate the battery if you have the right tools and data backup to restart your vehicle as many cars now have specific shutdown and restart procedures. Make sure you keep water away from the more sensitive car parts such as the alternator and spark plugs.

Dry clean the surfaces

Start dry cleaning the engine bay by vacuuming away any dirt and use the synthetic brush or toothbrush to remove any stubborn debris. It’s a good idea to wear some disposable gloves as you clean to avoid getting your hands dirty.

Wet clean the engine bay

Once you’ve removed the dirt and debris, wash down the inside and outside of the bonnet with water, making sure to stay well clear of any electrical components.

You can spray soapy water to remove any dirt from painted surfaces and then wipe clean with a microfibre cloth. Use pipe cleaners to get into any hard-to-reach areas. Wipe away any remaining dirt with cleaning wipes and give it a final rinse if there is any residue, again being mindful of any electrical components.

Clean the engine

After you’ve cleaned the surrounding areas, it’s time to move on to the engine itself. Use your cleaning wipes to remove any oil or grease. Again, you may need to use the toothbrush or pipe cleaners to get into any tight areas. Use a microfibre cloth to dry everything off. Do not use a hose pipe on the engine as this could cause damage.

Detail the engine

Now you’ve cleaned the engine, you can go over any finer details if you wish. You could use a trim restorer for any rubber or plastic surfaces or spray wax around the hood.

Put the battery back

If you have removed the battery, this would be the time to place it back. However, as mentioned previously, we advise against removing this unless you have the tools and knowledge.

In just a few simple steps, you now have peace of mind that your engine bay is squeaky clean and has zero debris causing an obstruction.

If you discover any issues when cleaning your engine bay, whether it be the engine itself or any surrounding components, visit your local Halfords Autocentre and we’ll take a look. If you find yourself needing any replacement parts, we’ve got thousands of car parts online. Simply enter your vehicle registration to discover the right parts for your vehicle.

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