How to Clean Your Car Engine the Right Way

Source | Gerard McGovern/Flickr

Do you clean your vehicle? The answer’s probably yes. But do you know how to clean your car’s engine bay? If not, that’s like taking a shower but never brushing your teeth. Don’t be that person; wash your engine, too.

Now you might be thinking that no one sees your engine bay except you and the occasional mechanic, so who cares, right? Well, like with the rest of your vehicle, cleaning prevents damage and keeps resale value high. A car engine bay covered in oil and grit is allowing premature wear in the pulleys and bearings, or hiding serious issues like gasket leaks. A clean engine bay allows the engine to stay cooler, operate efficiently, and keep your value high.

Difficulty

Good for beginners — A new DIYer will be able to complete the project

Time Required

1 hour

What you’ll need

 

Step-by-step guide on how to clean an engine bay

Hose it down

A quick pre-rinse does several things. It knocks off any of the loose dust and grit, makes it easier for the engine degreaser to spread around, and prevents spots from the soap quickly drying out. In short, a pre-rinse is essential.

Step 1: Wait until the engine is cool. It doesn’t need to be cold though—you just don’t want to introduce a bunch of cold water to hot parts. Pop the hood and let it cool for an hour. This is when you’ll put down the drip pans and absorbent pads to stop the chemicals and gunk from going down the gutters.

Pro Tip: Find a local recycling center that accepts both the used pads and the oily water from the drip tray.

Step 2: Disconnect the negative battery terminal or cover the battery with a plastic bag. Water conducts electricity, and you don’t want it to connect and make new temporary circuits. If you have a classic ride, cover the alternator, carburetor, and distributor with plastic bags. On a modern ride, cover the alternator and go easy with the water around the coil packs and fuse box.

Pro Tip: If you are using a power washer, use the low-pressure setting and rinse everything in the engine bay. Low pressure is better than high pressure here, as you want to clean off the crud, not blast it into the small crevices between components.

Spray it up

Step 3: Now it’s time to spray a liberal application of engine degreaser. Why use a degreaser instead of regular car soap? Your average car-wash soap is fine for grit and dirt but just won’t cut it on oil and grime. Go heavy on the engine degreaser on the typically nasty parts, like the starter and oil pan and anything else oily. Follow the directions on the bottle, but usually you will let it sit for a few minutes to get the most grime-lifting action. You can use a wash brush here for the seriously filthy areas. It has soft bristles that won’t scratch the paint or plastic.

Step 4: Rinse with low-pressure water again and take a look at your progress. Some engines that have never been cleaned in 300,000 miles will need the degreaser again. If not, it’s time to get busy with the automotive soap.

Step 5: Use an automotive car-wash soap to finish cleaning the engine bay the same way you would clean the exterior. Use an automotive wash mitt, get it soapy in the bucket, and scrub up the engine bay just like you would a rear quarter panel, then rinse.

Sweat the details

Step 6: Rinse with low pressure again and remove the plastic bags over the sensitive parts. If they need cleaning, professional detailers will remove the plastic fuse box cover or distributor cap and clean it by hand, where the electronics won’t be affected. Once clean and dry, just bolt them back on.

Step 7: Use a dedicated plastic cleaner to polish out fine scratches and restore shine to the engine bay plastics. Apply with a terry cloth and wipe off with a clean microfiber cloth. For the metal bits, a metal polish will brighten them up. They are all a bit different, but in general, grind a bit into the metal surface until the polish starts to turn darker, then wipe off with a clean cloth.

There you go. That’s all you need to learn how to clean your car engine. Now step back and enjoy your work.

Any detailing experts around? Let us know your engine bay cleaning tips and tricks!

Comments

  1. Jessica Powell says:

    Thanks! I’ve been for a good guide on this and this one is great, very detailed and well-explained.

    • Andy Jensen says:

      Thanks Jessica. Just remember each vehicle will vary in how you was it. This is just a guide, but I’m glad you found it useful. 🙂

  2. Bruce Wilber says:

    Good advice, I have been gently washing my engine bays for a while. And, yes it is hard if the car has gone many miles since cleaned. One thing I like to do last is start the engine again and let it idle for a few minutes to check that water did not get somewhere it should not have and it help dry the engine bay also.

  3. Dustin Y. says:

    Great Information! Thank you for posting it. I have been washing the engine bay of five cars in my family for the past 10 years without any serious problems. Just wanted to add a couple of notes. First, use a regular blower to blow off loose dirt, leaves, dust, and any other items from the engine bay. This gives the engine cleaner a better chance to clean all parts of the engine. Use the same blower upright as well to blow off road dust from the underside of the hood and the insulation if your car is equipped with one. Secondly, after cleaning the engine with water and degreaser, use the same blower to blast off water and moisture from all visible areas of the engine, but be careful not holding the blower nozzle too close to the electrical parts or you will force water into electrical connections. This step is just for removing excess water from top, sides, and bottom of the engine. Starting the car and letting it run for a few minutes will dry up all critical parts.

  4. Tommy Bowles says:

    Thank you for another very informative article. I clean the engine bay in my car and my wife’s car every time I wash the outside, which is almost every week in the warm months. After a good cleaning, I use my yard blower to start the drying process, as I want the dry the engine as good as I can before we put the cars on the road. The engine bays in both cars almost look showroom new.
    I really enjoy reading your articles.

  5. MShields says:

    I use spray tire foam/cleaner on my engine. Cuts the grime and leaves things shiny!

  6. Water does not conduct electricity, it’s the impurities. Of course it doesn’t really matter in most cases unless you use deionized water.

    • Linda Kay Farrow says:

      Yes. Water does conduct electricity. That’s how people are getting electrocuted at the docks at the lake of the Ozarks.

      • Herbert B Ballard says:

        Actually pure water is non conductive, but no one has truly pure water with no mineral content.

  7. Mark Ruby says:

    I live on a dirt road in my engine bay gets very dusty I off and wash my truck comma but I don’t always wash my engine bay. I’m going to wash my engine bay this weekend and clean out my K&N air filter. Thank you for the great advice. Look forward to more of advicefrom you.

  8. Cover the air intake with a plastic bag to prevent any water from entering it.
    Afterwards, I wipe down the aluminum parts (cooling lines, covers) with a cloth sprayed with silicon lube. Living near the ocean, this keeps the aluminum from oxidizing.

  9. I like spraying WD 40 on everything in the engine bay after it air drys a little. I’ve done this for years and my engine looks great and does not seem to effect anything. Also WD 40 displaces moisture and lubricates.

  10. Good advice. I agree with Jim to also cover the intake. You DO NOT want water getting into the intake! Do not forget to use a good silicone base rubber protector on your hoses. Preserves them.
    Ive been detailing cars for 20 years and this is something I always recommend to customers. If you want the outside to look new again you also want the engine compartment to match. My wifes car has 86k on it and the engine bay looks like it just came off the dealer floor. The mechanics love me!

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