5 Steps To Wash Your Car Engine At The Carwash

The outside of your car isn’t the only part that gets dirty. How do you keep your engine clean? What do you need to do? It’s just as important to keep your engine clean as it is the outside of your car. The exterior might look good, but grime and dirt can hide in your engine and eventually lead to problems.

How do you wash your car engine at the carwash?

The best way to clean your engine is to let your vehicle cool down. You’ll want to cover any electrical parts with electrical tape or plastic, then spray the engine down with an automotive degreaser. The last cleaning step is to spray it down, then scrub away the grime.

We’ll walk you through what to use for a degreaser in addition to things you should look out for when cleaning your engine. Engine cleaning can be helpful in some situations that we’ll cover.

We know the importance of keeping a clean vehicle inside and out – having seen some seriously grimy engines ourselves.

Why wash a car engine?

The most important part of your vehicle can get dirty.

Between sand and dirt on the road flying up from your undercarriage and the various spills you can create when trying to refill fluids, it’s entirely possible that your engine is much dirtier than you expected.

While a common attitude is to leave your engine alone, it could actually use the help to keep the stuff you picked up on the road from clogging filters – or making it really difficult to work on your vehicle.

A clean engine also helps you detect leaks.

Ever had a leak that wasn’t bad enough to be obvious?

A dirty engine marred by grease and dirt, makes those leaks even harder to find.

With a clean engine, you’ll be able to spot a leak much more easily, because it will be the dirtiest part under the hood.

How do I wash out my engine?

The first thing you’ll want to do is shut off your vehicle and let it cool completely.

Spraying water, especially cold water, onto hot metal can readily damage engine components. Get it cool enough that you can touch it with your bare hands. 

This will also give you the chance to collect some supplies, like electrical tape, a small vacuum like a shop vac, a bristled brush, a hose with a pressure nozzle, and some plastic bags.

You should also grab protective gear like a dust mask (you might be surprised!), safety glasses to avoid chemicals, and rubber gloves.

Next, you’ll want to disconnect your battery terminal. You might need a socket driver or a wrench for the purpose.

Protecting your electrics

You’ll want to cover your electrical components as well as you can. While some suggest a towel or t-shirt, try a plastic covering, including a plastic bag. A t-shirt offers more of a filter than protection.

Check your caps

Your engine has a variety of caps for areas like oil, coolant, windshield washer solution, etc.

Make sure these caps and dipsticks are in place and tight so you don’t find yourself flooding your engine oil with higher pressure water, because that could cause problems.

Remove big stuff

In some cases, you might find dirt or other items that aren’t greasy but will be in the way of the rest of the process.

Find anything big or obvious, like a chunk of leaves or pine cones or get those out of there.

A vacuum isn’t a bad idea here to avoid touching things by hand, or if they are in hard-to-reach places.

Put some degreaser on

You can find automotive degreaser at any hardware store or auto parts place.

Ideally, you can apply this without splashing too much on filters or electrical components as it doesn’t need to get in there to clean.

After spraying on the degreaser, let the mixture sit for about 10 minutes.

You are allowing the degreaser to do its work and soften grime while you patiently wait and get ready to get in there and push that dirt and engine-clogging junk away.

You can then spray it off using a hose and pressure nozzle and eventually a towel. This would normally the hard part, but the degreaser should do a good job of cutting through the gunk and making it easy to just blow away with water.

Don’t get too close to your engine with a pressure washer or spray; you don’t want to strip any metal away or hit electrical components by accident.

Use a brush

There will inevitably be parts of your engine that a towel or spray can’t quite clean. Use a hard bristled brush to get the gunk off that doesn’t quite fall off with degreaser.

We recommend using long gloves while doing this and being careful when scrubbing hard. 

Engines can have sharp and hard parts that can cut of cause some bruising if you miss and bang an elbow on something.

A brush, with a small amount of moisture, is also much more friendly to clean electrical parts like near your battery and alternator.

Use compressed air

Try compressed air for those nooks full of dust and dirt that even the degreaser and towel might have a hard time reaching.

You have a couple of options here: many places sell small cans of compressed air meant for cleaning electronics.

You could also use a regular compressor with the right attachment – and possibly the compressor part set on slightly lower than normal.

This can help blow out things that should not be there – and are away from the reach of anything else.

Dry it

You are best off hand drying your engine once your bay is all washed up. Do so quickly, too, because water and metal will produce rust.

You don’t mind getting covered in grease using a basic, highly absorbent towel.

Get your engine as dry as possible. Water, especially old standing water, does a number on the exterior of engine components.

How often should I wash out my engine?

The answer depends on your climate and your roads. Do you live in the northeast and midwest where the department of transportation salts the road every year?

Salt is not good for metal components, and you should wash your engine at least once per year, if not more often.

Another help for salty roads is a regular auto car cash. 

Be sure to select the undercarriage wash option to as they will send jets of nicely pressurized water under the frame to force salt off metal surfaces.

Put it back together

Remove anything that kept water from spraying, then reconnect your battery once the engine is dry. You can drive when you are ready, with a clean engine.

Should I remove my battery?

You don’t need to, but you definitely can. We also recommend covering your battery with something of a plastic tarp – like suggested earlier, to keep water away from these water-sensitive parts.

Do I need to polish my engine?

If you like to look at your engine, you can add what is called engine bay dressing. Engine bay dressing is sprayed on and allowed to sit for 30 minutes before washing. This applies more to vehicles that are used for show.