How to Pressure Wash a Car in 13 Steps With Safe GPM & PSI


how to pressure wash a car safely
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Now it’s time to remove debris and dirt or perhaps getting dried mud off your car.

Hi, in this article of ‘How to pressure wash a car safely’ I am going to discuss each step that is required to clean your car efficiently using a pressure washer.

how to pressure wash a car safely

Not to mention, I will be listing down all the necessary accessories that you may require for getting the job done.

Also, the precautions that I believe you should consider completing the washing without damaging your car or even the car paint.

So, without any further delay, let’s learn the procedure step by step.

First thing first. Let’s see if you should pressure wash a car or not.

Is Pressure Washing Good or Bad for Your Car?

In a nutshell, it is NOT bad. Otherwise, I wouldn’t be here to write this article for you.

Let’s see why it is good to use a pressure washer to clean your car.

  • It saves a hell of a lot of your time to pressure wash your vehicle than hand washing.
  • You can’t achieve the detailing in cleaning without pressure washing.
  • If you want to minimize scratching during washing, then pressure washing is your best bet. Any grit that sticks to the towel during manual washing can cause scratches on the car body.
  • Minimizes the use of water to accomplish the job.
  • Cleaning a large vehicle can be a daunting task if you do it manually instead of using a pressure washer.

Now let’s talk about the other side of the coin.

It can turn into bad from good if you don’t use your common sense. I know you have it, just make sure you use it to do the washing appropriately.

Here are some preventives that you should consider before pressure washing. Or else the result of pressure washing a car can turn into a nightmare for you.

  • First and foremost you have to choose the right PSI washer for car washing. 2000 PSI or less is considered to be the safe PSI for pressure washing a car. On the other hand, if the GPM is equal or less than 1.6 then it is safe and enough for washing your car. Maintaining a safe PSI level is more important than maintaining safe GPM.
  • You have to choose the right degree (between 25 to 40 degrees) nozzle. Otherwise, you are creating a chance of damaging your car glasses and perhaps the car paint. Don’t dare to use the 0 (zero) degree nozzle, please. Most of the cases the 0 (zero) degree nozzle is labeled as ‘blast’ and it’s red-colored.
  • Initially, you will have to stand keeping enough distance from your car before turning on the pressure washer. Keep about 4 to 5 feet distance between the nozzle and the car surface initially until the water jet gets weak.
  • Keep the window rolled up. Also, make sure you closed the door and trunk so that water doesn’t go inside.
  • You must use the approved / accurate detergent for pressure washer instead of regular soap, shampoo, or other liquid.
  • Park the car in the right spot, best if you park it on concrete or any hard surface. If you wash over gravel, small stones can fly up and hit the paint. If you wash over sand or dirt, there is a chance that you will end up splattering dirt all over the recently cleaned car.
  • If possible wear eye protection to keep your eyes safe from debris or grit coming out while cleaning the wheels.
  • If you have stickers on your car body then spray them on a 90-degree angle. It will prevent peeling off the stickers.
  • Make sure to dilute the detergent with water before applying on the car.

If you take the above preventive you are good to go. Not following any of those can lead to damage to your car.

How often you should pressure wash your car is totally up to you. But my suggestion is to do it only when it is necessary to do it. I mean don’t overdo it unnecessarily.

Ok, now you know all the precautions and hopefully prepared with everything.

Give yourself a break.

Done?

Now let’s begin washing step by step.

Don’t have a pressure washer yet? Read the review of the best pressure washer for cars here.

How to Pressure Wash a Car Safely – a Step by Step Guide

Step 1: Get ready with the proper nozzle. Let’s say a 40-degree nozzle. Use a longer hose. It will help you to keep the pressure washer at a safe distance while washing the whole car by moving around it conveniently.

Step 2: Before you apply any detergent, simply rinse the car with water using a pressure washer. That will remove the debris and dirt stuck to the car surface initially.

Stay about 7-8 feet away from the car initially. Gradually go closer if it requires.

Apply the water from top to bottom.

Step 3: Once you end up rinsing the car surface, concentrate on rinsing the area of the wheels before applying any detergent.

Step 4: Now add any top-quality detergent in your detergent tank that is perfect for car cleaning and also good for your pressure washer.

I assume your pressure washer comes with an onboard detergent tank. If not then apply soap using hand and soft towel or mitt.

Alternatively, you can use any high-quality foam cannon instead of applying detergent from the detergent tank.

Step 5: Change the nozzle to the soap nozzle that comes with your pressure washing unit.

Step 6: Now apply the soap from bottom to the top with broad and overlapping strokes.

Step 7: Give special attention to the wheel well, grill, and bumpers as these are the areas where mud and dirt tend to collect most.

While cleaning the wheel keep the spray nozzle at least 6” away from the tires.

Use the wand to wash the hard to reach areas.

Step 8: Let the soap soak for 6-7 minutes but don’t let it dry all the way. Keep it wet so that it keeps working.

Step 9: In the meantime use any rotating brush attachment to clean heavily soiled area or any stubborn dirt.

I suggest you use two different attachments for car surfaces and wheels.

The idea is to keep your car surface free from scratching.

If you clean the wheel area and use the same brush to clean the car surface, there is a chance that you pick up dirt, pebbles with the brush and damage the car’s paint.

Step 10: Replace the soap nozzle with the first nozzle (45 degrees). Perhaps it is the green nozzle in your case.

Step 11: Rinse off the detergent now with water from top to bottom. Make sure to wash all the soap/detergent. Again start doing this from 7-8 feet away from the car’s surface.

Step 12: Make sure you drain the soap tank when you are done.

Step 13: Once the cleaning is done apply quality wax or polish in a circular motion with a microfiber towel or mitt.

Let’s watch a video on this:

Pressure Washing a Car Engine

So far I have talked about cleaning the car’s surface only. Now I am going to guide on pressure washing your car engine safely.

Look! It isn’t as risky as you might think.

But of course, you have to take some precautions like you took while washing your car.

Now, what does this mean for you?

Nothing serious, just follow these steps to pressure wash your car engine safely.

  • Let the engine cool down before spraying water. It doesn’t have to be super cool. As long as it’s not too hot it’s ok to start the washing.
  • Most of the cases you have to cover these following items with polybags. They are – alarm system, battery wiring, loose electrical connections, alternator, distributor.
  • Use any good quality degreaser if it’s a greasy or oily stained engine. If not, then use any water-based engine & machine cleaner.
  • Spray the cleaner into all the corners of the engine bay.
  • Use a scrubber or brush to clean any stubborn dirt or for reaching the difficult areas.
  • Leave it for soaking for a few minutes.
  • Now, as you did in case of washing the car’s surface, use a 40-degree nozzle and up to 2000 PSI pressure washer (either electric or gas unit).
  • Then rinse up the engine bay standing at 3-4 feet away from your car.
  • Next, let the engine dry and then remove the polybag cover. You can use a dryer to expedite the drying.

Pressure washing your engine bay is as simple as that!

Pressure Washer PSI vs GPM

I am going to finish this section pretty short. Just in case you don’t know exactly what PSI and GPM are.

PSI stands for pounds per square inch. Meaning the amount of pressure that the unit generates.

The GPM stands for gallons per minute. It is the flow rate. Meaning the amount of water that comes out of the unit.

When you multiply these two you get the Cleaning Unit (CU).

So CU = PSI x GPM.

In fact, CU is the actual measurement that you should use to compare any two pressure washers.

Let’s see why.

Look! If you see unit A has got bigger PSI than unit B, very likely you will consider the unit A is more powerful than unit B, right?

Wrong!

Only PSI doesn’t decide the overall power and cleaning ability of a pressure washer.

Consider the following example.

Unit A – 2300 PSI and 1.2 GPM = 2300 X 1.2 = 2760 CU

Unit B – 1900 PSI and 1.5 GPM = 1900 X 1.5 = 2850 CU

See, the PSI of Unit B is way less than unit A. However, as the unit B has the higher GPM and resulting in a higher CU, unit B is the winner here. Meaning unit B has a better cleaning ability than unit A.

I don’t want to extend this topic anymore. I hope everything is clear by now.

Final Words

Now you’ve successfully cleaned your favorite car with a pressure washer.

Let’s recap.

In this article of ‘how to pressure wash a car safely,’ I guided you step by step on the car washing system.

I noted down every preventive that you should take before and during the washing process. That will help to prevent any kind of damage to the car paint or fragile parts.

I wrote the engine washing part separately as you should not wash it like you wash the car surface (almost the same except for a few extra measures).

I also gave you an idea of safe PSI and GPM level and other accessories required to do the job perfectly. You have a separate section to understand the difference between PSI and GPM, also what the heck the cleaning unit (CU) is.

A brief guide to help you decide whether you should go for an electric pressure washer or gas pressure washer as well.

Have I missed anything?

Make a list of all the things you believe I should include here and comment that list below.

Source: Car washing procedure from wikihow.

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