How to Safely Wash a Car Engine

If you’ve ever taken your car in to get it detailed, you know that one of the finest feelings is popping open the hood and seeing the engine shining like it just came off the lot. You may have thought about trying to get the engine that clean on your own, but is it safe?

As long as you take precautions to protect your engine, especially the electrical components, you can safely wash your engine bay at home. However, if you feel uncomfortable dealing with your engine’s components while preparing them for the wash, consider taking it to the shop instead and let the pros do it.

Here are the steps for safely washing an engine –

1. Let the engine cool down.
2. Disconnect your battery and tighten caps and covers.
3. Cover electrical components with plastic.
4. Apply a degreaser.
5. Scrub, especially gunky areas, as necessary.
6. Rinse with low-pressure water.
7. Dry the engine bay.
8. Reconnect the battery and plastic covers, remove plastic bags.

Keep reading because we’ll look closer at how and why to clean your engine bay, as well as some of the products that can make it easier. First, let’s break down these steps in a bit more detail.

Wash A Car Engine; Step by Step

1. Cool The Engine

If your engine is still piping hot when you spray cold water on it, not only are you likely to get a lot of steam, you could also damage yourself or your car. The rapid contraction caused by the sudden change in temperature can lead to parts warping or even cracking.

For these reasons, we recommend letting your engine rest for at least 15 minutes if you’ve been running it. On the bright side, this is the perfect amount of time to get your supplies in order.

That said, if your car hasn’t been running recently, letting it run for about five minutes before cleaning your engine can warm up the grease enough to make it clean up a little easier. Just make sure you don’t forget it’s running to let it get too hot.

2. Disconnect And Check

You should at least disconnect the negative terminal to the battery. You can also remove the battery, should you prefer. Disconnecting your battery is safe, but you can read here first about what can happen when you disconnect the battery in cars with computers.

Now is also an excellent time to check your covers, dipsticks, and caps. If any are loose, tighten them.

3. Cover Electrical Systems

Use plastic with something to hold it in place, such as zip ties or electrical tape, to cover-up electrical components. These include the fuse box, the alternator, spark plugs, and coil packs. If your engine air intake is exposed, you should cover that as well. Covering will help protect everything under the hood, vulnerable to water damage.

4. Apply A Degreaser

There are many kinds of degreasers available, which we will explore in more detail below. Be sure to check the instructions, as some degreasers are concentrated and need mixing with water before application. Most degreasers will need to sit for at least a few minutes for maximum effectiveness. Also, we recommend wearing protective gloves and goggles, as many degreasers can damage your skin and eyes.

5. Scrub

If it has been a long time since your engine bay was clean, some parts may have lots of built-up greases. Using a brush with synthetic bristles, give them a solid scrub and apply more degreaser if necessary. Spots like valve covers are especially prone to grease build-up.

If there isn’t any substantial build-up, you can skip this step.

6. Rinse

Using a source of low-pressure water, such as a garden hose if you’re at home, rinse off all of the degreasers. Start in the back and work your way forward in a back and forth motion. Avoid spraying directly at any electrical components and also avoid areas where water is likely to pool.

Also, rinse around the exterior around the engine bay in case any degreaser splashed onto your paint.

7. Dry

If you have time, you can leave the hood up and let the engine bay air dry for a couple of hours. Otherwise, you can use compressed air, a leaf blower, or shop rags to dry everything.

8. Reconnect

Once things have dried completely, you can reconnect your battery and remove the plastic from the electronics. You can run your car for a few minutes, so it comes up to operating temperature and evaporates any remaining liquid.

What Can I Use To Degrease The Engine Bay?

A degreaser is a cleaner designed to break up the matter that’s typically not water-soluble, like oil, organic soils, and, of course, grease. Many household cleaners are degreasers, such as kitchen sprays and oven cleaners. There are even recipes online for how to make sprayable degreasers with household goods.

While these degreasers can be used on your engine bay too, you may find yourself spending a lot more time and effort scrubbing to get everything clean. Also, you can save yourself some hassle using degreasers designed for engine work, which come in different styles but are better suited for the job.

Is Simple Green Heavy Duty Cleaner Good For Engines?

Simple Green creates a lot of high-quality, non-toxic products. Their heavy-duty cleaner is an all-purpose cleaner and isn’t as powerful as some of the others we recommend here. That said, it comes with some advantages. It is non-toxic, so you don’t have to worry about runoff from cleaning your engine hurting your lawn. Also, since it is milder, it can be used on a variety of surfaces, like plastic and vinyl.

Can You Use WD-40 To Clean An Engine?

Standard WD-40 is not the most effective way to clean or, especially, degrease the components in your engine bay. However, WD-40 produces a degreaser in their specialist series that is great for degreasing your engine as well as other degreasing jobs you may have. It is available in both aerosol and non-aerosol triggers.

How Do You Use Gunk Engine Cleaner Foamy?

Gunk produces both an engine degreaser and a protector to help keep your engine clean after your hard work. Just apply the degreaser and let it sit for 5 to 10 minutes before rinsing and then apply the protector after drying.

Does Engine Degreaser Damage Paint?

Degreasers are excellent at breaking down the grime that accumulates on your engine. Unfortunately, they are also great at breaking down other things too, including the paint on your car.

A concentrated amount of degreaser can cause some minor damage to the outside of your paint or wax; left unchecked, it can cause more damage, including discoloring the paint, leaving residues, or causing peeling.

Rinse off any degreaser that gets on your car’s paint immediately. We also recommend rinsing off the area around your car’s engine bay once you’ve finished cleaning it, just in case any degreaser splashed out that you didn’t notice.

Is It Safe To Powerwash A Car Engine?

Following our guide, you can get a great wash on your engine with a simple garden hose. A pressure washer might not be necessary, but is it safe? The answer is a qualified “yes,” with some important caveats. Using high-pressure water increases your odds of getting water into your wiring, fuse-boxes, and other places you don’t want it, even if you’ve properly covered them.

To use a pressure-washer safely:

• Use a 40-degree spraying nozzle.
• Keep the spray nozzle around 3 feet from the engine.
• Point it away from all (properly protected) electrical components.

How Often Should I Wash My Car’s Engine?

If you’ve seen our post on how often you should wash your car, you have a good sense of what cleaning routine is best for your car’s exterior. But what about your engine bay?

The same things that get the outside of your car dirty get into your engine bay. If you live somewhere with lots of snow, pollen, dirt, or gravel roads, you’ll want to clean your engine bay every three months or so to prevent build up.

If you live somewhere with more ideal conditions, you should be able to get by cleaning your engine bay about twice a year to keep up with the build-up.

Why Clean Your Engine Bay?

Now that we know how, it’s worth asking why clean the engine in the first place. Even the aesthetic reasons have their practical side. Keeping the engine bay tidy is going to help keep your resale value high down the road.

A clean engine comes with other perks, too, though. Grease traps some heat in your engine, causing it to run hotter. Also, if you ever have a leak, it is much easier to find the source in a clean engine compartment. Your rubber hoses and plastic parts will also appreciate the cleaning and last longer.

Most importantly, you’re going to feel great when you see your engine bay shining like new underneath the hood.