Balancing Act

DIY: How to Wash and Clean Your Engine Bay

Has it been a decade since you’ve last cleaned your engine bay? Does it look like the engine bay on my 2012 Prius? I’ve never washed it since it left the lot at Cabe Toyota of Long Beach, CA back in May of 2012.

If your engine bay is like mines, then it’s about time we give them a nice wash. This is an easy task and should take about 20-30 minutes of your time. You’ll need an empty spray bottle and a gallon jug of your favorite multi-purpose cleaner / de-greaser. I recommend Purple Power or Simple Green.

Tools and Materials Needed

Step 1

Make sure your engine is cool before cleaning. Remove leaves, twigs and berries around your engine bay and windshield cowl. Common problematic areas for accumulation of debris include:

  • the passenger side windshield cowl (right at the mesh vent area),
  • side fender walls
  • under-hood fuse box,
  • strut towers and
  • inverter

You may need a vacuum cleaner with brush attachment to assist in the removal of the aforementioned debris.

If your car has an alternator or exposed air intake, such as a carburetor or short ram air intake, wrap it up with a plastic bag. Since we’re hosing down a 3rd gen Prius, you generally don’t need to wrap anything in plastic unless you’ve made modification(s) that calls for the extra protection (spliced wires, exposed grounding wires, etc. such as adding aftermarket DRLs or fog lights where wire splicing and chassis grounding is involved).

Wrapping the air intake tube opening is recommended so water doesn’t enter the duct and sit in the air box and condense in a heated engine bay. I stuffed a terry cloth in the opening while hosing down the engine bay:

The water won’t be able to physically travel into the throttle body, so it’s really optional but I recommend that your wrap the opening up. If water enters the air box, you’ll need to take it apart and dry with a shop towel.

Step 2

Set your garden hose spray nozzle to “Flat” setting, if available, or “Spray” and hose the engine down for a good 3 minutes at medium water pressure.

Do this to flush out any loose debris such as twigs, dried up leaves (or parts of), broken twigs and berries and to wash off top layer of dust.

Step 3

Fill up an empty spray bottle with your cleaner then generously spray the entire engine bay with the multi-purpose cleaner of your choice. Purple Power was on sale at the local AutoZone, so I stocked up and picked up two 1-gallon jugs of it.

Go hog wild and indiscriminately spray your engine bay. Get in between all nooks and cranny that you can access.

If you think you’ve got everything covered, go ahead and spray some more.

I also removed the plastic cylinder cover and sprayed the engine block beneath it. Then I waited 5 minutes for the multi-purpose cleaner to penetrate the engine bay and components. I ended up emptying two full spray bottles of multi-cleaner before I called it a day.

Step 4

If you have a lot of problematic areas with tough grime build-up, use a brush and scrub the baby down to loosen the build-up. Spray more multi-purpose cleaner, scrub and repeat until the grime is completely loose and agitated.

Step 5

Spray your engine bay with high water pressure until clean. Switch between “Jet” mode and “Flat/Spray” mode for problematic or hard to reach areas. Using shop towels, dry areas around wire harness and cable connectors.

Let your engine bay air dry, then stand back and admire your engine bay that’s now so fresh and so clean. If you start your car before the engine bay is completely dry, you may see some smoke from water heating up and steaming or agitated oil and other motor fluid burning up, nothing to be alarmed about. If you have exposed or spliced wires, make sure they are completely dry before starting your car. You don’t want to inadvertently create a short circuit.

I recommend cleaning the engine bay once every quarter to ensure that it stays neat and clean. Plastic pieces around the engine bay, such as the areas around the upper front bumper retainer clips and window cowls may have faded with time and weather, as they are on my Prius. That’s why the plastic trims in the photo above look like they’re covered in dust even after a thorough cleaning. To restore them to their former shiny black glory, use Armor All Outlast Trim and Plastic Restorer.

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