Cleaning your Engine Bay

We like to keep the exterior & interior of our vehicle shiny clean, but how often do you think about under the bonnet? The engine bay accumulates dirt & grime the more you drive, especially in wet & windy weather conditions. A clean engine bay is not only appealing to potential buyers if you’re looking to sell, but more importantly, you will be able to spot any leaks or issues a lot sooner, rather than them being hidden too long under dirt & grime. A very dirty engine bay also poses a risk of fire; for example when flammable liquids leaks like oil covers exhaust manifolds. It is also easier for your mechanic to diagnose & repair faults & replace parts on a clean vehicle. The engine bay can be a bit intimidating, but with our helpful tips, we will help to make this job as quick & simple as possible.


The first step is finding a suitable location & an appropriate time. Not only is it damaging to the environment to allow contaminated water (containing toxic chemicals) to flow into council drains, but it is also illegal. Most self-serve car wash places have an engine wash bay specifically for this purpose. If you’re at home, you can place a drop sheet underneath your vehicle so that any run-off can be collected in a container & disposed of properly. A biodegradable degreaser is a great option, however, do not assume it is 100% environmentally friendly, as it may mix with other fluids in the cleaning process that are not as environmentally friendly.

Cool Down:

You need to allow the engine to cool before you start. If the car’s been running, pop the hood to speed up the cooling process & give the car at least 15- 30 minutes to cool down. Not only will you avoid any burns, but hot engine components will cause any plastic you will be needing to cover & protect sensitive parts to melt. There is also a risk of damage caused by rapid contraction; warping & cracking if hot parts are sprayed with cold water, not to mention causing the degreaser to dry too quickly & cause unsightly spotting.

Organise Supplies:

You will need the following products to get the job done right:
  • Scrubbing brushes (soft & stiff synthetic bristles)
  • Gloves and Safety glasses
  • Biodegradable Engine Degreaser
  • Plastic bags & electrical tape
  • Access to water (garden or pressure hose)
  • Plastic drop sheet (if at home)
  • Microfibre towels
*Dilute the degreaser according to directions on the label & transfer into a spray bottle.

To Start:

Before you begin with the chemicals, if necessary, start by removing as much debris as possible with a vacuum or brush. This will also help loosen grime and dirt before degreasing.

Cover up:

You will need to ensure certain parts of the engine bay are kept dry & protected.  Firstly, make sure all caps, covers & dipsticks are tight & securely sealed. Using the plastic bags & electrical tape, cover the air intake, battery, alternator, coil, spark plugs & any exposed electrical components. You do not want water and grime leaking into these openings as it can cause electrical faults & starting issues. This will not only protect these components, but let you clean more easily & thoroughly without worrying about the risk.


For this step you can choose to use warm water in a spray bottle to firstly moisten all surfaces, as this can help the degreaser to adhere evenly & prevent it from drying & spotting on any warm surfaces. Alternatively, simply spray your degreaser generously all over every exposed surface. Let it sit for a few minutes to break down all the dirt & grime. PPE is encouraged if you have a mask or protective eyewear handy, as you need to be careful not to breathe in the spray. Pay particular attention to areas of grime build up.

Scrub it down:

Depending on how dirty the engine block is, or how long it was since its last clean, you may not need to use a brush. However, for extra dirty areas, use a synthetic, soft bristle brush to work the degreaser in & remove grime until clean.

Rinse Off:

Use a garden hose working the spray evenly from back to front, to rinse off the degreaser & any dirt that’s been loosened, making sure you’re avoiding any electrical components you covered up previously. Be aware, if you’re at the carwash, you need to be careful with the pressure hose & use a low-pressure setting as high water pressure can force water into areas that can be damaged from water infiltration. Try to avoid getting the matting/ padding on the underside of the bonnet overly wet if your vehicle has this, as it can cause issues when the extra weight of the water can cause sagging and deterioration over time.

Drying Off:

If it’s a nice warm day, air-dry your vehicle while leaving your bonnet up, then dry thoroughly over all surfaces with an absorbent microfibre cloth to remove any excess moisture. Try to get into all the nooks & crannies, especially around any electrical components. This step not only dries your engine bay, but removes any residual grime. If you have access to compressed air or a garden blower, you can use this to speed up the drying process & help to remove water from any areas it shouldn’t be. When dry, don’t forget to remove the plastic bags.

Service You Can Trust:

If you have any questions about, or issues with your vehicle, we are here to help!  Give one of our friendly team a call on 0412 161 776 & remember to follow us on Facebook for more information, tips and monthly giveaways.