5 Steps In Detailing Your Engine Bay (Comprehensive Guide)

5 Steps In Detailing Your Engine Bay (Comprehensive Guide)


This post is an in-depth guide in detailing your car’s engine bay. 

In this engine bay detailing guide, we’ve sectioned it into 5 digestible steps to make it easier for you to follow. 

We’ll also cover frequently asked questions like:

  • What to cover when cleaning the engine
  • What cleaning products to use and if it’s safe to use WD-40
  • How to avoid damaging the engine and electronics
  • If the engine should be cleaned hot or cold
  • And in which parts you use a hose and a pressure washer

If you want your engine bay to look as awesome as when you first got it, this guide is for you. 

Let’s get started.

Tools Needed To Clean The Engine Bay

Unlike the car interior, the engine needs more tools in cleaning. But we’ll keep it simple and just list down the most important tools you’ll need like:

  • A bunch of microfiber towels
  • Detailing brushes, pipe cleaners, paintbrushes, or even a toothbrush
  • Unused garbage bag
  • Paint markers
  • Cleaning wipes
  • Spray wax
  • Trim restore
  • Degreaser

Tip: For the degreaser, you can also use a mixture of water and dishwashing liquid or a mixture of vinegar, lemon juice, and baking soda (this is great for cutting crud and eliminating the smell. 

Common Engine Dirt

Before diving into the actual cleaning, let’s talk a little bit about the kinds of dirt that get in your engine bay. It can be 1 of 4 things. 

  • Classic daily driving dirt (mostly dust)
  • Grease and oil
  • Mud (common for trucks going through puddles)
  • Dirt and rust (mostly 20-year-old cars)

Knowing what kind of dirt your engine has will let you know what cleaners to use. This is important if you want to avoid damaging the parts. 

Some cleaners work well for the paintwork but will damage plastic and rubber hoses. We’ll go over the engine bay cleaning process thoroughly so we can cover the cleaning process however your car engine looks. 

For the cleaning process, we divided it into 5 steps:

  1. Preparation
  2. Dry Cleaning
  3. Wet Cleaning
  4. Drying The Engine
  5. Detailing

Now let’s go over these steps in detail.

Step 1: Preparation

This step can seem unnecessary, but it’s very important. It’ll help you save cleaning time and will also prevent damages to the engine. 

1. Get all the supplies you need in one place

This saves time from needing to remember where you put what. It saves you from repetitive trips back and forth to your garage storage space.

Tip: Use gloves to protect your hands from oil and chemicals. Use safety glasses to protect your eyes from splashes. 

2. Isolate the battery by disconnecting it from the cables

Doing this step makes it easier to clean the space around the battery and tray holding it too. If you decide to keep it in the bay, just disconnect that battery from the cables.

This prevents short circuits from happening. 

3. Seal caps and covers

The engine bay has components that can tolerate a little water but not soaking, like the alternator and distributor. 

To make sure water doesn’t get into these parts, press down on the spark plug caps. Some spark plug caps are in areas where water can sit and collect. These parts don’t dry out easily so make sure the caps are sealed to prevent water from entering. 

engine bay spark plug caps


Tightly close the lid of the power steering reservoir and brake fluid reservoir too. 

Also, make sure engine oil dipsticks aren’t popped up. If it is, simply push it down to seal it. If your car has automatic transmission, do the same for its dipstick. 

Other engine bays have plastic covers protecting the parts that shouldn’t get soaking wet. Make sure water doesn’t go behind those covers. 

Rule: Avoid using pressured water when spraying the engine area. Cable connections are water-tight but can get loose over time because of vibrations and heat cycles. Even if it doesn't get into the sensor, it can still cause corrosion, still a problem for you over time. 

Step 2: Dry Cleaning

There will be a lot of loose road grime and dust settling on top of your engine parts. We want to get rid of those before you get the whole engine bay wet so you won’t be pushing loose dirt on areas we can’t easily reach. 

Tip: This will be a very dusty process, wear a dust mask or any face covering if you can. 

1. Agitate surface dust

Simply brush off surfaces to agitate the dust making it lose. 

If you have a car cleaning gun just turn the air-only dial on and set it to the lowest pressure possible to loosen dust easier and faster. 

The car cleaning gun collects dust on the nozzle but to make sure nothing flies off escaping to other surfaces, use a vacuum to suck the dust-up.

Work the brush on brush or car cleaning a gun on easy surfaces first and progressively move on to hard-to-reach spots. 

Brushes are great but they can’t reach tight spots like under cables and sensors. This is where a car cleaning gun will come in handy. 

Brush as much surface as you can and since this is a fairly quick step, you’ll be done with this in under 10 minutes.

2. Some cars have small metal intakes while others have larger ones

These metal intakes can get discolored, pitted, corroded, and stained over time so you have to clean them too. 

engine bay aluminum cleaning


For this, you’ll have to use the metal-wire brush or better yet a rotary tool with a metal attachment. 

Tip: Be careful with surrounding rubber and plastics but like hoses. 

Step 3: Wet Cleaning

For many, this can be the scariest part of cleaning the engine bay. Many car owners get anxious about getting areas that need to be kept dry wet. 

But don’t fret over that, we’ll teach you how you can avoid engine damage when getting your car wet. 

Before diving into the process, many ask if the engine bay should be cleaned when it’s hot or cold. 

The answer is: either way. 

But it’s best if it’s just a little wet, just enough for you not to get burned when you place your hand on top of it. It helps make the degreaser work better because it makes dust and grease come off easier. 

Tip: Don’t use cold water on your hot engine. Using cold water on hot metal can make in contract. It can either warp or crack engine parts. 

1. Cover the bulk of the engine, including the spark plug caps with an unused garbage bag

engine bay cover actual engine


We’ll clean top to bottom so we don’t want water dropping to the engine bay soaking it eventually. 

2. Clean the hood liner

Hose down water on the underside of the hood including the hood liner. Then spray and wipe the surface off with the degreaser. You can also use a car cleaning gun to merge the spraying and wiping step into 1. 

engine bay hood liner


If the hood liner isn’t clean enough, use a carpet cleaner to clean it further. 

Tip: Hood liners can sag over time, if you have to get it soaking wet, limit it to once or twice a year.

3. Clean the outside part of the engine bay

These are the parts around the covered portion. Pick a side to work on first and soften the surface by wetting it down.

Then use cleaning wipes to absorb dirt and remove oil and grease. Rinse the loosened dirt with water and spray degreaser to the same surface. Brush the degreaser all over the surface. 

engine bay wet cleaning the outside part


Better yet, use the car cleaning gun again at low pressure with the nozzle brush attachment on to merge these 2 steps. 

Tip: For tight spots, use a pipe cleaner brush. It gets into surfaces you won’t even be able to see. 

Finish this step by rinsing the surface you’re working on again. Then repeat the process as you work your way around. 

4. Clean the actual engine

Remove the garbage bag carefully so you don’t get water on the engine. 

If your car has a big engine with lots of hoses and wires, getting it cleaned can seem overwhelming. 

To make it easier, divide the surface into 2 and work on one area first. 

Rule: Don’t hose down on the engine to avoid damaging it. 

Reaching tight spots can be challenging, for this you can remove the intake temporarily. 

First, use cleaning wipes to remove grease and oil. Accumulated grease can become a thick layer of insulation between the cold air around the engine and the engine itself. 

engine bay wet cleaning the actual engine


Removing this layer of grease will help the engine to cool better avoiding premature engine damages. 

Next, clean it off with a degreaser, using a brush for tight spots. 

Then wipe it down with a clean microfiber towel. It gets the grease stuck on your engine sucked up on the towel surface. 

Tip: For tighter spots, your hand can’t reach, wrap a pipe cleaner or a toothbrush with the microfiber towel. 

engine bay drying tight spots using pipe cleaner wrapped in microfiber towel


Step 4: Drying The Engine

This is the actual drying portion. Grab another microfiber towel and wipe all the surfaces dry. 

You’ll notice as you’re wiping away, the towel picks up extra dirt left behind in the previous step. 

Other than this, you’ll also notice puddled water around on some areas, make sure to dry these spots completely too by letting the towel soak the water or having a vacuum suck the water up. 

Step 5: Detailing

Again we’ll do it top to bottom. 

1. Detail the hood liner

By this time, the hood liner starts getting dry but it can either leave wet marks or dull color. To make it look new again, spray a black non-flammable fabric dye on the hood liner. 

engine bay spraying hood liner with fabric dye

2. Detail painted surfaces

Squirt the spray wax starting from the hood down to the surfaces around the engine then buff it with a clean microfiber towel. 

3. Rubbers and plastics

For rubbers and plastics use a water-based trim restorer. 

It’s not greasy so it won’t collect dust. And also helps rejuvenate and protect rubber and plastic parts of the engine. 

engine bay trim restore for rubber and plastic parts


Rule: Don’t use WD-40 or motor oil because it will make the surface too greasy collecting dust faster. This will cause another layer of dirt to insulate the engine and it will damage the rubber. 

Use a brush to cover rubber hoses and plastic parts. Don’t mind making a smooth coverage, for now, just wipe down as much surface as you can. 

Then let it soak for at least 10 minutes. 

Rule: Don’t apply the product to the engine belt. It can make it squeaky or can cause it to slip. 

After soaking, grab another clean microfiber towel to wipe off the excess product so it won’t collect dust. 

4. Rusty parts

Rusty bolts and other metal car parts can ruin the overall look of your cleaned engine. 

What you can do is grab the metal wired brush and scrape off as much rust as you can. Then pain off the piece with paint markers. 


engine bay rust solution

5. Faded lettering

These are mostly on reservoir caps. Use the paint markers to color the raised portions of the letters. 

engine bay reservoir caps detailing using paint marker


This keen attention to even the tiniest of details will set your work apart from others. 

Lastly, put the hood liner back on together with the battery and the intake you took off earlier. 

And now your engine bay detailing is complete!

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