Rick's Free Auto Repair Advice

How to clean an engine and engine bay

Safe way to clean an engine and engine bay

On auto forums I often see people asking why their engine won’t start after they’ve power washed their engine. Well, there are safe ways to clean an engine and engine bay and not so safe ways. I’ll go through the steps you must take to prevent damage to electrical and plastic components on your engine and in your engine bay. What you need to clean an engine and engine bay

Spray degreaser
Oil absorbing pads for under the engine
Nylon scrub brush (Wire brush for really caked on greasy areas)
Press ‘n Seal plastic wrap or tape and cling wrap
Hose and jet nozzle
Compressed air

Step 1 to clean an engine — disconnect the negative battery terminal

Your engine must be cool and de-powered before you start cleaning. If the engine was running, wait an hour before hitting it with water.

You’ll be spraying water in your engine bay, so you don’t want any live power to the electrical components. Disconnecting the negative battery terminal kills all the power. However, on many modern vehicles, disconnecting the power also wipes out memory settings for your windows, seats, radio and even the electronic throttle body. So do some research on how to perform a throttle body relearn procedure before you even start the project.

Step 2: Remove the vanity cover

Modern engines have a plastic vanity cover over the top of the engine. That has to come off so you can clean the components under the cover

Step 3 to clean an engine— wrap all electrical connectors with Press ‘n Seal plastic wrap.

Yeah, they’re supposed to be water tight, press n seal plastic wrapbut if water gets in, you’ll wish you had taken the time to prevent it. Follow the wiring harness and simply wrap the plastic wrap around each connector, making it water tight. If Press ‘n Seal doesn’t stick, use cling wrap and tape the ends with electrician’s tape.

Step 4: Plastic wrap around the alternator

Simple enough; just wrap a large piece of plastic warp around the alternator to seal the vents and keep water out.

Which engine bay degreaser to buy?

Everyone will tell you to buy biodegradable engine gunk engine degreaserdegreaser, and that’s decent enough advice as far as it goes. You want the degreaser to biodegrade. But one you dissolve the grease, the waste water is no longer biodegradable. In fact, it’s considered toxic and can’t be draining into the street or storm sewer. Here’s how you get around that — oil absorbent pads.

Place the oil absorbent pads under the engine and in front of the vehicle. As you rinse off the grease, it will stick to the pads, allowing the biodegradeable degreaser to run off. Then simply toss the greasy pads in your trash.

oil absorbent pads

oil absorbent pads

Step 5: Start the engine cleaning process

Use compressed air to blow off loose debris from the engine and engine bay (wear eye protection). Then spray degreaser onto the engine and around the engine bay. Let it soak for the recommended time. If you have heavy grease spots, use the wire brush to score the surface grease and then re-spray more degreaser. That allows the chemical to get deeper into the grease.

Use the nylon brush around the engine and engine bay to loosen dirt.

Step 6: Rinse with a garden hose and a weak jet stream

Do NOT use a pressure washer to clean your engine. Many under-hood components are plastic and can be easily damaged by high pressure. Discovering you’ve blasted off critical plastic vacuum ports/lines is the last thing you want after performing an engine clean.

Step 7: Use compressed air to blow off as much water as possible

Step 8: Remove all the plastic wrap

Step 9: Reconnect the negative battery terminal

Step 10: Install the vanity cover, start the engine and perform a throttle body relearn. Then reset your radio, seat, mirror settings.

©, 2021 Rick Muscoplat

 

Posted on by Rick Muscoplat

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