How to Clean the Engine Bay
- How to
- Car ownership
FixMyCar explains how to clean your engine bay in this step-by-step guide.
Book car repair nowEllie Dyer-Brown
Thursday February 06 2025
5 min read
When you clean your car, you probably focus on the outside and interior. After all, these are the most visible areas. But there’s another place that can benefit from a good clean: the engine bay.
Not only can keeping the engine bay clean increase your car’s resale value, but it can also boost performance. This guide explains how to do it step-by-step.
Contents
Safety first: prepping for engine bay cleaning
Safety first: prepping for engine bay cleaning
Before you get started, make sure you’re working safely. Your engine contains sensitive electrical components that shouldn’t get wet, so take these precautions:
Make sure the engine is cold. Never clean an engine that has recently been running.
Remove the battery if you have the right tools and data backup for a restart.
Use waterproof covers to protect sensitive parts like the alternator and spark plugs.
Learn how to change a car battery.
What you’ll need
You don’t need to buy specialist equipment to clean the engine bay. A few household products will do the trick.
You’ll need:
Soft bristle brushes (various sizes)
Microfibre towels
Disposable gloves
Soapy water in spray bottle
Degreasing cleaning spray
Pipe cleaners
How to clean your engine bay step-by-step
1. Protect sensitive components
Disconnect the negative battery terminal (labelled ‘-’) using a spanner or pliers to loosen the nut. Then, use plastic bags or waterproof covers to protect parts that could be damaged by moisture, such as the:
Ignition wires
Air intake
🚨 Note: Modern cars may require a memory backup or code when disconnecting and reconnecting the battery. If you're unsure, consult your manual.
2. Remove loose debris
Wear protective gloves, and start by removing any debris from the engine bay, like twigs and leaves. You can do this using your hands or with a soft brush. Compressed air can also be helpful for this step, but it isn’t essential.
3. Apply degreaser spray
Spray degreaser on greasy areas and let it sit for a few minutes to break down the grime.
🚗 PRO TIP: Avoid getting degreaser on the exterior paintwork as it will strip away any previously applied wax and ceramic coating.
4. Clean the bonnet
While the degreasing spray is working its magic, wash down the inside and outside of the bonnet with water, avoiding electrical components.
Spray soapy water to remove dirt from the paintwork and wipe it clean with a microfibre cloth. Give the area a final rinse to remove any residue.
5. Clean the engine
Use soft-bristle brushes to loosen dirt and grime. Pipe cleaners can help reach tight spots. Then, gently rinse the area with water, avoiding direct contact with electrical components.
🚨 Note: Avoid using a strong stream of water to clean the engine as it can force liquid into places it shouldn't be.
6. Dry and detail
Use a clean microfibre cloth to dry everything. For a finishing touch, apply wax spray on the bonnet or use trim restorer on plastic and rubber components.
7. Reconnect the battery and remove covers
Reconnect the battery’s negative terminal and remove plastic covers from sensitive components. Then step back and admire your clean engine!
Engine safety check
While you're cleaning under the bonnet, why not take the opportunity to ensure everything’s in working order?
Check all hoses and lines are intact and free from cracks.
Look for loose bolts and frayed belts.
Why should you clean the engine bay?
Cleaning your engine bay takes less than an hour and brings plenty of benefits. Although it’s not essential, it’s something you should consider doing if you’re experiencing a lack of performance or thinking of selling your car.
The benefits of engine bay cleaning
Boosts resale value 🚘
Potential buyers will almost certainly want to see what’s under the bonnet, and first impressions count. A clean engine indicates that your car has been well looked after, which increases its value.
Improves performance 🚀
Debris like leaves and twigs can block the engine air intake, which has a knock-on effect on performance. The fuel mixture won’t burn properly without enough air, leading to poor fuel efficiency, lack of power, and black exhaust smoke.
Extends engine life 🛠️
When dirt and grime build up, they can lead to corrosion, which will shorten your engine's lifespan. Cleaning the engine bay means you’re less likely to see parts failing prematurely.
Helps you spot problems early 🔎
Regular cleaning lets you keep an eye on fluid levels, leaks, and general engine health.
How to maintain a clean engine bay
Now your engine bay is sparkling clean, how do you keep it that way? Here are our three top tips.
Park under a carport or use a protective car cover to shield the engine bay.
Create a regular cleaning schedule. Staying on top of maintenance makes cleaning less daunting!
Use a professional detailing service if you’re short on time.
Looking for affordable car repairs or maintenance? FixMyCar can help.
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Written by Ellie
Ellie is FixMyCar's Content Writer. She has over three years of experience writing about cars and regularly collaborates with automotive experts to provide trustworthy advice for drivers that is easy understand. Her work has been featured in Yahoo! Finance, iNews, The Daily Express and The Sun. She has a BA in English literature and an MA in creative writing from Durham University. Outside of work, Ellie follows F1 and eagerly awaits Ferrari's next era of dominance in the sport. She drives a Suzuki Swift.