How to Clean Under the Hood of a Car? – 11 Steps to Remember

Written by

Bruce Sonnier


Marcus Dutton

how to clean under the hood of a car

Cleaning the car engine is necessary for keeping the car running in good condition, preventing mechanical and electronic problems, and prolonging the car’s life. But if you don’t know how to do it, you can always go for an under the hood cleaning service. Or you can just follow this tutorial on how to clean under the hood of a car.

In the process, expect to do cleaning off debris, spraying degreaser, scrubbing, rinsing, and drying. But there are also some precautionary steps. Read further to be familiarized.

What You Will Need to Follow This Tutorial


Cleaning under the hood may involve working on sensitive parts and a lot of greasy mess. But listed below are the tools that can make cleaning more convenient for you.

  • Leaf Blower or Air Compressor – You can use either for blowing out debris in the engine. Either would also come in handy for drying the engine.
  • Drip Pan, Absorbent Mats, and/or Rags – Any of these can be used to collect the runoff from the engine or scrub and clean it.
  • Plastic Bags – Plastic bags are for protecting the parts of the engine that are vulnerable to water.
  • Tape – You can secure the plastic bags with tape.
  • Socket – We use sockets to unfasten the battery cables. Make sure to use the appropriate size.
  • Degreaser – You need an under the hood cleaner or degreaser to break up all the oil and fuel residue on the engine’s surfaces.
  • Stiff-Bristled Brush – A stiff-bristled brush can be used to scrub off caked-on oil and dirt.
  • Power Washer or Hose – Either can be used for rinsing.
  • Microfiber Towel – A microfiber towel would be good for wiping the engine dry.
  • Engine Protectant – The agent will make the engine look new, make cleaning in the future easier, and prevent its vinyl, plastic, and rubber parts from cracking and breaking.

Step by Step Instructions


Along with the proper tools, you would also need patience and caution to achieve a clean engine. So follow the following steps with care:

Step 1: Cool Down the Engine

Although some advice is to clean the engine when it’s a little bit warm, as it helps clean off the gunk and dirt. But to avoid causing any damages to the engine, the best way to clean under the hood would be to cool it down first before doing any cleaning.

Cleaning when it’s hot would cause its parts to shatter or get damaged. You could also get burned if you deal with a hot engine.

Step 2: Remove the Debris

You can pick up any debris at reach, like around the fenders, below the windshield, in the grille, and surrounding areas. As for hard-to-reach debris, you can blow them out with either a leaf blower or air compressor.

Step 3: Place a Drip Pan Beneath the Engine

When you wash under the hood, road grime, oil, and chemicals would be washed out of the engine. You wouldn’t want them to stain the garage floor or get into the waterways. So you should place a drip pan beneath the engine to catch them.

You may also place some absorbent mats or rags around the drip pan if you think it won’t catch all the mucky mess. Or you can just use absorbent mats and rags instead if you don’t have a drip pan.

Step 4: Protect the Sensitive Parts With Plastic Bags

Before washing the engine, you must protect its sensitive parts by covering them with plastic bags secured with tape. Particularly, the parts that can get damaged when in contact with water are essential to the car’s operation. Protecting them allows you to clean more thoroughly while preventing any damages to the engine.

The parts that need to be protected are the following:

  • Air intake
  • Alternator
  • Battery
  • Engine control unit
  • Fuse box
  • Electronics
  • Electrical connections
  • Relays
  • Sensors
  • Spark plug holes
  • Distributor cap
  • Any part you think might get damaged by water

If you don’t know where any of the aforementioned parts are located, consult your car’s manual.

Step 5: Remove the Filters and Battery Cable

Simply covering them is not enough for some parts, or they can’t be covered with plastic bags. Such parts are the air filters and battery cables, which will have to be removed.

You will first remove the air filters. These parts are very vulnerable to water. Water can also accumulate in them, which can potentially damage other parts of the engine. You’ll most likely have to remove the air intake filter. And if the cabin air filter is exposed, you would need to remove it too.

Afterward, make sure to cover the filter intakes with plastic.

The battery cables should also be removed to prevent a short from happening in your car when water gets in contact with the engine. Using a socket with the appropriate size, loosen the cable nuts that fasten the battery cables on the battery. Remove the negative cable and then the positive cable.

Once the positive cable is removed, avoid getting it in contact with any metal part of the car to prevent getting short in the vehicle.

Step 6: Spray Degreaser on the Engine

The engine tends to get very greasy. So when you car wash under hood, you need to spray degreaser on it thoroughly.

Spray it on the engine’s non-sensitive metal parts and hoses, and fluid containers. Avoid spraying degreaser on sensitive areas with electronic connections and where degreaser can leak or drain through the engine.

Depending on how greasy the engine is, you may let the degreaser sit for 10 to up to 20 minutes or more before moving forward to the next step. But if it’s not too greasy, you can simply spray a coat on its surfaces and proceed to the next step.

Step 7: Scrub the Surfaces of the Engine, Rinse, and Repeat If Necessary

If the engine is not too dirty, then scrubbing may not be necessary. You may just rinse the engine. But if you notice some parts with oil and dirt caked on, scrubbing is needed. You can scrub out the grease and dirt from the engine’s surfaces with a rag. And for build-up with caked-on, clean with a stiff-bristled brush.

Rinsing can be done with a power washer or a hose if you don’t have a power washer. When rinsing with a power washer, wash only in a light setting. Also, rinse starting from the back, going to the front.

Thoroughly rinse all the degreaser out. But try not to spray directly at electrical components nor spray too much water on areas that won’t dry quickly.

Step 8: Dry the Engine

So that the engine gets thoroughly and quickly dried and water will not get into any of the sensitive parts, it’s best to dry it yourself rather than let it air dry.

You can either use a microfiber towel or you may even make the drying much quicker with the use of a leaf blower or an air compressor. Make sure it gets completely dried, especially paying attention to areas that are hard to reach and areas wherein water can accumulate and would not be able to drain.

Also, after washing the engine, dispose of its run-off properly to not pollute the waterways. Avoid pouring them down the drain. Don’t pour them on the street or soil, as that would only delay the release of those chemicals until the next rain.

Instead, pour them out from the drip pan into a metal or plastic container specifically for fuel or oil using a funnel. You can send the run-off to any automotive repair store, as many of them dispose of such chemicals for free. But contact them first before you send the run-off to make sure.

Step 9: Remove the Plastic Bags

To be safe, also wipe dry the plastic bags before you remove them. Once dried, carefully remove them from the sensitive parts.

Step 10: Apply Protectant to Vinyl, Plastic, and Rubber Parts

An extra step you can do when you detail under the hood is to apply an engine protectant on the vinyl, plastic, and rubber parts. But avoid using it on the sensitive areas that have been covered with plastic bags.

Step 11: Replace the Parts Removed

Finally, when your car’s engine is all clean and protected, put back the battery cables and filters.


Now that you know how to clean under the hood of a car the right way, it should not be tricky to start. Make sure you do the necessary precautionary measures before doing any cleaning.

Have any thoughts on this article? It would be nice to hear what you think and if you like it in the comments. And it would be great if you could share this article for other car owners to know about the hood detailing.

5/5 - (2 votes)



"As the content writer of Charmcitycirculator, I intend to bring just the best purchase options and straightforward answers to your problems. Other than what we put up on our website, we hope to hear more from you. "

– Bruce Sonnier