How To Clean A Car Engine: Tips, Techniques, & More

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Many people feel that cleaning their own car engine is a daunting task, fearing that they might damage the electric connectors and other delicate and moving parts that make up a car engine. Fortunately, its modern design involves plastic shrouding that protects most of its part and some sturdy plastic housings for the electric connectors, which makes cleanup much easier.

But before we delve into how to clean car engine, it makes sense to know the benefits of doing this chore and learn more about how to clean car engine components.

  • A clean car engine will prevent rust that is mostly caused by salt and road grime. Hence, periodic cleaning of your engine bay is known to prolong the life of your vehicle’s engine.
  • When your car engine is clean, it is easy to spot any problem areas and leaks of any kind.
  • It can prolong your car battery’s life.
  • When a mechanic sees a dirty engine, he may think that you are not a fastidious customer and thus less likely to complain about shoddy repairs.
  • If someone forgets to install the engine oil cap, the end result is a huge mess throughout the entire engine and engine bay.

What You Will Need in Advance 

Before you learn how to clean car engine, it makes sense to prepare first the tools listed below:

  • Nut wrench to loosen the bolt on the negative and positive terminal on the battery
  • Small plastic bags or plastic cling wrap to cover spark plug inlets, distributor cap, and loose wires
  • Drip pan lined with absorbent mats
  • Brush kit
  • Gloves
  • Eye protection to avoid getting the engine degreaser in your eyes
  • Water mist or regular hose (avoid high-pressure hose as it may disconnect the wires)
  • Flashlight

Of course, you will also need cleaning products such as:

  • Engine degreaser; there are countless products you can choose from, but the vast majority of them tend to work in the same way
  • Anti-corrosion chemical like CLR
  • Baking soda and water paste


How to Clean Car Engine

1.  First thing’s first, remove any debris from the engine bay. They may include dried leaves, twigs, grass, etc. Then, use a nylon brush around plastic components and switch to a wire brush to break up the stuck on grime.

2.  Disconnect the battery by loosening the bolt on the negative terminal attach to it and tuck the ground cable to the side to prevent it from coming into contact with the terminal.

3.  If you decide to remove the battery from the engine bay (which is done by loosening the bolt on the negative and positive terminal), you can clean its tray, which also requires periodic cleaning. Once it is clean and dry, you may want to give it a coat of rust-resistant enamel, which you can also use in other steel parts of the engine.

4.  Soak the cable ends in a tin can filled with corrosion neutralizer.
5.  Protect the exposed wires, coils, and electric connectors with plastic wrap or plastic cling.

6.  Line your drip pain with absorbent mats and slide it under the engine. Take note that it is illegal to dump untreated wastewater into sewer gutters, so make sure that you dispose of it properly.

7.  Run your engine for at least five minutes. The idea is to loosen up the grease; however, don’t leave it running for too long lest you might burn yourself when you resume your cleanup.

8.  Apply engine degreaser. Spray the product on the engine from the bottom up to ensure total coverage and let it soak for the recommended time. Areas with thicker grimes will need an additional coat. Letting the product sit for five minutes or so makes the cleanup much easier.

9.  Once the grime or burned oil soaked in the degreaser, you can start brushing the engine with a stiff bristled or steel brush. While doing this, you may want to use eye goggles and gloves. (Note: You may want to skip this part when there is just a small deposit of grease.)

Another option is to rinse off the degreaser with a water mist, using as little water as possible.

If the engine still looks dirty after rinsing off the degreaser, reapply the product and allow it to sit for another few minutes.

10.  Use a leaf blower or pressurized air to blow excess water from the engine bay. But for a more thorough drying, you may also want to run your engine for at least five minutes, with the AC also on so the compressor engages.

11.  Once the engine is completely dry and cool, you may spray an engine protectant, which not only gives it a shiny appearance but also provides a protective layer of grease that makes cleanup easier next time.

12.  Wash the car. You should immediately wash your car to make sure that any engine degreaser that comes into contact with the painted components is removed. Also, any painted area that has come into contact with the degreaser should be waxed.

In addition, be sure that you use a different bucket, towels, and sponges on the body of the car.

The Proper Techniques: How to Clean Car Engine Safely

1.  Before you spray water directly into your engine bay, make sure that your battery is disconnected, i.e., the ground cable is tucked to the side to prevent any contact with the terminal, to prevent damage to the fuses, electrical components, among others.

But if you’re extra confident, you may remove and clean the battery outside of the engine bay. To do this, you’ll have to disconnect the positive terminal as well.

2.  Never use a steel brush when cleaning the plastic shrouding to prevent scratches.

3.  If you can’t find the spark plug inlets and distributor, which are ideally covered with small plastic bags or cling wraps, refer to your vehicle’s service manual. Take note that while your engine is relatively waterproof, this additional step offers a higher degree of safety.

However, avoid the high-pressure hose because it might remove the plastic covers or damage sensitive parts. Use common sense here.

4.  Before de-greasing, it is ideal to run first the engine for around five minutes. Afterward, shut it off and wait until you can safely touch the exhaust manifold. Never go beyond five minutes because you might burn yourself when you clean your engine.

Another thing to keep in mind: Never spray engine cleaners, particularly flammable solvents, on a hot engine.

5.  If you are using a concentrated water-based engine cleaner product, try it out on a greasy spot first. If the grime remains stuck on the engine, add more concentrated degreaser to the solution.

6.  Always read the product labels. If the package states flammable, never use the product on extremely hot engines or allow it to come into contact with direct flame lest it results in combustion or fire.

7.  If you are not that confident to follow all the instructions stated above or want to skip the use of water, you can simply use an all-around engine cleaner that can be used with or without water. Simply spray the product and mop up the dirt, hardened oil, and dust.

8.  De-greaser products can damage your car paint. Just to be on the safe side, apply a layer of car wax to the painted areas adjacent to the engine bay before spraying any cleaner to the engine. Also, keep a micro-fiber handy to wipe off any over-spray.

9.  Some people like to apply engine protectant (also called engine dressing) to their dry, clean engine, although others skimp on this. Proponents like the “shine” that highlights the auto engine detailing efforts and the uniform appearance it creates that a simple de-greasing can’t achieve.

People who are a big fan of engine dressing also like the creation of an additional barrier for everyday dirt, oil, and dust, which is easily washed off the next time.

Nonetheless, not everyone is a fan of engine dressing. However, many experts have attested that the only minor downside is that the shine makes any dust and dirt look more prominent.

How to Clean Car Engine: Final Word

Today’s car engine makes it easy and safe to clean the entire engine and the engine bay even by a lay person who practices common sense. After all, much of the engine is protected by plastic shrouding and all connectors are covered with thick plastic housing. So basically, your engine is fairly water-resistant, including the alternators.

Nonetheless, for extra protection you may want to cover any exposed wires, coils, and electric connectors with plastic wrap or plastic cling.

In a nutshell, if you learn how to clean car engine you can prevent rust and corrosion, and ultimately prolong the life of your engine and its battery. Moreover, a clean engine bay allows you to spot leaks such as coolant leaks.

To check for leaks, you can use a special UV dye that can be added into the oil fill. Afterward, run the engine, and drive around for a few minutes until it gets to normal temperature and the dye circulates.

Meanwhile, coolant leaks require a different dye that can be added to the radiator. Large trucks may need two bottles of dye because of the large volume of coolant. The dye will show the location of any leaks.

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