How and why you should clean your engine bay
Updated 12 Oct 2019
The more you drive your car, the more dirt and grime will accumulate in the engine bay.
Engines can start looking dirty very quickly, as they are exposed to all the environmental factors associated with driving in wet or windy weather.
If you plan on selling your vehicle, or just want to take pride in all aspects of your car, cleaning the engine bay is a simple and easy job that you can do yourself in as little as half an hour.
The first step is finding somewhere suitable to clean your engine bay.
It is illegal to dump contaminated water into city drains - which includes oil, coolant or degreaser - so you will need to find a suitable location to do the job.
Most self-serve car wash services have a provision to allow engine bay cleaning.
Alternatively, placing a plastic sheet under your vehicle that will allow runoff to be collected in a container and disposed of properly is a simple solution.
You can also use a biodegradable degreaser, as we do in the video below, which is safe to use at home as long as you are not attacking oil leaks or other fluids with it.
It is best to allow the engine to sit for a short period of time, to let the engine cool down.
A hot engine will cause the degreaser and other cleaning agents to dry quickly and leave unsightly spots all over the engine.
The more you drive your car, the more dirt and grime will accumulate in the engine bay of your vehicle.
You will need certain products to carry out cleaning of the engine bay. These include:
- Scrubbing brushes
- Gloves and Safety glasses
- Biodegradable Engine Degreaser
- Plastic bags
- Water, preferably a pressure washer or garden hose
- Microfibre towels
- Vinyl and rubber protectant
Using the plastic bags, cover any components that you would like to keep dry, such as the alternator, coil and spark plugs.
Getting water in these components may cause damage or starting issues, so it’s best to keep them nice and dry. Be sure to remove the plastic bags after you’ve finished!
It’s time to start cleaning! Firstly, rinse the engine bay down with the high-pressure washer or hose, starting at the back and working your way forward and making sure to cover as much as you can.
Have the pressure washer on a lower setting, as having high pressure may force water into connectors and other components which may cause issues.
It is best to avoid soaking the sound-absorbing matting on the underside of the bonnet if your vehicle is fitted with one as the extra weight can cause it to sag and fall apart over time.
Once you are happy with the rinse, spray your degreaser liberally over all surfaces, and go to town with a scrubbing brush, making sure to work on stubborn marks.
Allow the degreaser to sit for a few minutes to give it a chance to break down the dirt and grime.
For the next step, grab your pressure washer or hose and rinse off the degreaser solution.
If there are any problem areas, focus on them with the spray bottle and scrubbing brush until they are clean.
It’s now time to let the engine bay dry. The easiest way is to leave the bonnet open, especially if it is as warm sunny day.
You can also use compressed air or a garden blower to remove the water, if you have access to one.
Now that the engine is dry, it is time to remove the plastic bags. You can also buy special rubber and vinyl protectant to give the plastics a showroom shine!
Simply apply with a foam applicator to all parts of the engine bay and then remove the excess with a microfibre towel.
Once you feel that you have removed all the dirt and grime from your engine bay, you can feel proud that you have the best-looking engine on the street!
Carrying out this cleaning routinely will keep the engine bay looking new, will help to track down any leaks, and show prospective buyers how much you have taken care of your car.
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Image credits: BMW engine bay David Ainley
Finding a passion for cars from a young age, Joel carried out work experience as a mechanic whilst at school before starting an apprenticeship after finishing year 12.
After almost 10 years on the tools and in customer service, he moved into the IT realm as a Data Analyst and In-House mechanic at AutoGuru.