When it comes to using a pressure washer to clean your car’s engine and engine bay area, there is a right and wrong way to do the job:

Pressure washing your car engine can be safe, for sure, but should you even bother?

Regardless how often you open the hood to check the levels or look at your car engine, you have to admit it looks damn good clean.

Take a look:

Before and after pressure washing an engine

Okay, so pressure washing the engine can be safe.

And a clean engine looks great…

What does the car operating manual say?

While researching this how-to guide I read through 11 different car manuals. Four mentioned nothing about cleaning the engine and seven had a tiny section saying if you lived in a snowy area with salted roads you may want to clean the engine with non-corrosive chemical at end of season.

So there are situations where pressure washing a car engine and bay area is about making it function better and last longer compared to just making it look better.

Here’s everything you ought to know to get your engine bay clean without damaging anything.

Engine Components to Protect

Electric enclosures have an IP Code to classify how protected they are against water and dust.

Electric pressure washer enclosure ip5 rating
Pressure washer next to me has IPX5 enclosure ingress protection rating.

The pressure washer sitting next to me is an electric AR Blue Clean with blue plastic enclosure. It says it has IPX5 rating. The ‘X’ says it is not rated for dust protection (as its not critical to function) and the ‘5’ says it is protected against water jets. Other IP ratings with regards to water are:

  • IP1 – Dripping water protection
  • IP3 – Spraying water
  • IP4 – Splashing
  • IP5 – Water jets
  • IP6 – Powerful water jet
  • IP7 – Water immersion

If you can, check the IP rating of electric enclosures in your car engine area. If you can’t then just assume they are less than IP5 and cover them with plastic bags.

Things to cover with plastic bags:

Pressure wash engine things to cover

And other electrics like car alarm system.

Best Chemicals to Speed Up the Job

There are two situations you may encounter, each will require a different chemical cleaning solutions

Very greasy and oil stained engine

Simple green engine degreaser concentrate

This situation will require a degreaser.

If you buy the Simple Green concentrate pictured right you can dilute it with water to create a solution of varying potency.

It is biodegradable and safe to use just be sure to follow the instructions to get the best potency mix for the job.

Dusty but not too greasy or oily

Simple green general purpose car engine cleaner

For this situation you can use a general purpose all-in-one type cleaner.

Simple Green makes a great product designed to be a general purpose solution strong enough for your car engine and also perfect for the bumpers and wheels.

Best Pressure Washer to Use

Any of our 7 best pressure washers recommendation will do the job quick-smart. A heavy-duty or light-duty machine can be used.

A heavy-duty, really?

Yes… The force of water stream is dictated by the nozzle you use and how far you hold the water spray from the surface. Use a 40-degree nozzle and hold it 3 or 4 feet from the engine and the engine feels less force than from your garden hose.

Watch this 3 minute 37 second video to learn how to clean your car’s engine and engine bay safely:

5 Steps for Pressure Washing a Car Engine Bay Without Causing Damage

1.) Gather everything you need before starting

  • Plastic bags and tape to protect electrics
  • Safe non-corrosive chemical cleaner to make stains, dirt and grime come off easy when pressure washing
  • Small scrub brush (toothbrush works) to get the cleaner into all the nooks and crannies
  • Pressure washer with correct nozzle (white or green tip)
  • Shammy or other drying towel
  • Vinyl care product

2.) Take precautions

  • Make sure engine isn’t hot. Ideally, you want it warm but not hot. Wait 15 minutes if you have just driven to the area where you will be pressure cleaning
  • Cover alarm systems, distributor, alternator and other electric connections with plastic bags and tape them on so they aren’t blown away when pressure washing
  • Read chemical cleaner label to ensure it is non-corrosive, biodegradable and water based so as to not damage the engine plastics etc.

3.) Apply cleaning product

  • Spray cleaning product liberally to all areas of the engine making effort to get it into the tough areas
  • Leave the cleaning to work for a minute or two
  • Use scrub brush to get the cleaning product into awkward places and to knock loose the tough dirt and stains
  • Repeat above steps for stubborn areas

4.) Pressure wash clean

  • Use correct nozzle – the 25-degree “lifting” green tip or 40-degree “spraying” white tip will be perfect for the job
  • Stand back and keep spray nozzle 3 – 4 feet above the engine to keep the pressure engine feels low, move closer if you judge the spray isn’t forceful enough

5.) Dry, remove plastic bags and apply protection product

  • Use shammy or drying towel to thoroughly dry the engine
  • Remove plastic bags from electrics
  • Leave it to air dry for 30 minutes
  • Apply vinyl care product or other long term corrosion protection product
  • Take some photos for your friends to see


  1. Things to cover with plastic bag image above is from Jalopnik.com article also on pressure washing car engine.

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