How to Clean an Engine Bay Safely

Worth the effort

Why clean your engine bay?

• Spot leaks early

  Oil, coolant and power steering leaks are easy to see on a clean engine and almost invisible on a grimy one.

• Clear out leaves and pollen

  Fall leaves and spring pollen pile up in the cowl near the windshield and around the air intake. Clearing them helps drainage and airflow.

• Higher resale value

  Buyers and dealers pop the hood. A clean engine bay tells them the car was cared for.

Before you start

Engine bay safety checklist

1. Let the engine coolNever spray water or degreaser on a hot engine. It can crack hot parts and the cleaner flashes dry instantly. Warm to the touch is the limit.
2. Know what to keep dryThe air intake or filter box, the alternator, exposed fuse boxes and any open electrical connectors.
3. Cover sensitive partsA plastic bag or plastic wrap over the intake opening and exposed electrical parts adds peace of mind.
4. Remove loose debris firstPull leaves, pine needles and twigs out by hand or with a shop vac, especially from the cowl area.

Step by step

How to clean an engine bay

1. Lightly mist the engine bayA gentle spray of water, just enough to dampen the surfaces. Not a soaking.
2. Spray a diluted degreaserUse an engine degreaser or all-purpose cleaner diluted for engine use. Work from the bottom up so it doesn’t streak.
3. Agitate with brushesSoft detailing brushes for plastic covers and hoses, a stiffer brush for greasy metal. Let the cleaner dwell a minute or two, but don’t let it dry.
4. Rinse with low pressureA garden hose on a gentle shower setting. Rinse top to bottom. No pressure washer close up.
5. Dry it offBlow out water with compressed air or a leaf blower, then wipe the plastic covers with a microfiber towel.
6. Remove covers and idle the engineTake off any plastic bags, then let the engine run for a few minutes so the heat dries hidden spots.
7. Dress the plastics (optional)A water-based, non-greasy dressing gives plastics and hoses a clean, satin look. Avoid oily products that attract dust.

Read this if you drive one

Hybrids and electric cars

Don’t do this

Engine bay cleaning mistakes

1. Pressure washing up closeHigh pressure can force water into connectors and sensors and strip labels. Low pressure only.
2. Cleaning a hot engineCleaner bakes on, and cold water on hot metal is never a good idea.
3. Using undiluted harsh degreaserIt can stain aluminum and dry out rubber hoses. Follow the dilution on the label.
4. Greasy, shiny dressingsThey look wet for a day, then collect dust and dirt.

Low pressure.
Cool engine. Every time.