How To Clean An Engine

Dustin Hawley | Oct 04, 2022

Nobody wants a greasy, grimy engine. Like everything else on your vehicle, you want yours to be squeaky clean. But how do you clean your car engine safely and effectively? Let’s break down the process.

how to clean an engine

6 Steps To Cleaning Your Engine

1. Gather Your Supplies

Before you get started, you’ll need to have the necessary supplies. First and foremost, this means getting your hands on a degreaser. Degreasers come in two main categories: solvent-based and water-based.

Both varieties will get the job done, and contrary to popular perception, they require special disposal. Even if the degreaser is “biodegradable” or “environmentally friendly,” it’s considered hazardous waste once you dissolve motor oil and other chemicals.

In general, solvent-based degreasers tend to be the most effective. For one thing, they work faster than water-based products. They do a better job of cutting through thick layers of grease and getting to the bare metal.

The main downside is their potent smell, giving you headaches in an enclosed area. If this concerns you, a water-based degreaser may be better. Regardless of what you use, you may also want to pick up some foam or gel for your vertical surfaces.

While buying your degreaser, get yourself a drip pan and at least three packages of absorbent mats as well. You may also need the following: 

  • Knee pads
  • Nylon brush
  • Wire brush
  • Flashlight
  • Air compressor
  • Air hose

2. Warm Up The Engine And Let It Cool Down

A degreaser is most effective when the grease itself is soft. Start your engine and let it run for a few minutes to achieve this. At the same time, you don’t want your car engine to be too hot. It could boil off a water-based degreaser or cause a solvent-based degreaser to ignite. So, let your engine cool until you can touch the exhaust manifold without burning yourself.

It also helps if you’re doing this in warm weather. The grease will be easier to wash away, and your engine will dry out faster afterward.

3. Prep Your Engine Bay

Before you spray anything, you’ll want to protect all your delicate electronics. If there’s a plastic cover under your hood, remove it and degrease it separately. Now, disconnect the lead from the battery’s negative terminal to de-energize all of your electronics. You can remove the battery entirely if you want to, but it’s unnecessary.

Next, use plastic bags to cover anything you don’t want to get wet. The battery is an obvious candidate. But so are the ignition wires, engine control unit, and any other computers. If your air intake is exposed, it’s wise to cover it, so you don’t get water into your air filter.

Use colorful tape to mark each bag you’ve used so you don’t forget to remove it later. You should also lay your absorbent mats under your vehicle at this time.

4. Degrease

The first step is to remove any surface dirt, leaves, and other debris. Use a nylon brush to scrub away as much dry debris as possible, vacuum it out, or blow it away with an air compressor. Once you’ve done a dry scrub, spray the engine with water and do another scrubbing.

Next, spray on your degreaser, and let it penetrate for about 10 minutes. Apply extra degreaser around caps and hoses, and anywhere else you notice excess buildup.

You don’t have to scrub down the entire engine. However, it can help to scrub around heavily-soiled areas like valve caps. Again, use a synthetic brush, not metallic, so you don’t damage your finish.

5. Rinse

When satisfied, use a low-pressure spray to rinse down your engine. A standard garden hose is fine, but you can also use a pressure washer on the lowest setting. Work from back to front, thoroughly rinsing all surfaces and removing all the degreasers. Avoid spraying electrical components as much as possible.

When the engine stops dripping, set your absorbent mats in the sun to dry. After they’ve dried out, follow your local hazardous waste guidelines for proper disposal.

6. Dry And Finish

Wait a few minutes for the water to evaporate, and wipe up whatever remains with a soft cloth. If you’re having trouble with the nooks and crannies, you can blast the water out with an air compressor.

If you want more protection, you can spray an engine protectant onto your freshly-cleaned engine. This adds a shiny protective layer designed to make future cleanings easier.

Wait another hour or so until you’re sure the engine is completely dry. Remove all your plastic bags, and reconnect your negative battery terminal. That’s all there is to it!

Why Clean Your Car Engine?

For some, cleanliness is a given. But what if you don’t care about your engine’s appearance? Why should you go through the trouble of cleaning it? Here are a few good reasons to degrease your engine at least once a year:

  • It prevents corrosion. Along with grease, road salt can also build up on your engine, causing it to rust. A thorough cleaning removes this buildup.
  • It makes maintenance easier. Without a layer of grease over everything, it’s easier to take care of essential repairs. Not only that, but you can see more of your motor. A clean engine makes it easy to spot leaks, cracks, and other damage.
  • It reduces the risk of fire. Grease is a combustible material, and there are probably leaves or pine needles under your hood as well. Removing this material reduces the risk of your engine compartment ever catching fire.


Cleaning your engine is a simple, straightforward process that can be performed in just a couple of hours. By degreasing your car engine once a year, you’ll reduce the risk of corrosion and fire and allow yourself to identify potential problems. As importantly, you’ll know that your car is squeaky clean – inside and out.

Explore new car previews
2023 Ford F-Series Super Duty Preview
2023 Ford F-Series Super Duty Preview
F-Series Super Duty trucks got what they needed for the 2023 model year. Ford announced a more powerful line of heavy-duty trucks with a load of available new tech, great standard safety features, and unique upfits to make the trucks more appropriate for specific industries.
Read the full review
2023 Honda Pilot Preview
2023 Honda Pilot Preview
The fourth-generation 2023 Honda Pilot is about to go on sale, and Honda substantially upgrades it over the popular third-generation model it replaces. Honda will offer the redesigned 2023 Pilot in Sport, EX-L, TrailSport, Touring, and Elite trim levels in December 2022.
Read the full review
2023 Ram 2500 Heavy Duty Rebel Preview
2023 Ram 2500 Heavy Duty Rebel Preview
Ram used the 2022 State Fair of Texas to show off its new 2500 Heavy Duty Rebel, a beefy off-road truck that retains its work-truck capabilities. It brings hardcore off-road upgrades such as an electronic-locking rear differential and a rear limited-slip differential.
Read the full review
Read all articles

Scroll to the top
New Car Preview
2023 Kia Telluride Preview
Most Dependable
2019 Vehicle Dependability: Most Dependable Family SUVs
Most Popular
10 Most Popular Luxury Cars
New Model Update
New for 2019: Infiniti
New Car Preview
2023 Ford Maverick Tremor Preview
More related