How To Clean Pistons Without Removing Them [CHEAP]

Carbon buildup on the pistons is actually very common, especially on older engines. It doesn’t matter how you maintain it, carbon buildup is a product of the combustion of gasoline. Is carbon buildup on pistons something that you should take care of?

Carbon buildup on pistons can lead to abnormal combustion because the carbon has a tendency to absorb both oxygen and fuel, therefore, extinguishing the flame in the combustion chamber.

The carbon buildup on the pistons will disrupt the normal combustion process and can lead to poor fuel economy, failing the pollution test, uneven power stroke thus causing engine knock, and more.

Now that you have been informed about how carbon buildup on pistons affects engine performance, it’s time to take action. Here is how to clean pistons without removing them:

Key Takeaway

How To Clean Pistons Without Removing Them [CHEAP]

  • Open the hood and remove any plastic covers to expose the engine.
  • Locate the PCV vacuum hose. It is usually next to the intake manifold.
  • Insert a carb cleaner straw into the PCV hose.
  • Start the vehicle and rev it to 2000 RPMs.
  • Spray the whole cleaner bottle in short sprays.
  • Take the vehicle for a test drive.

How To Clean Pistons Without Removing Them [CHEAP]

How To Clean Pistons Without Removing Them [CHEAP]

It’s time to clean the carbon buildup on the pistons. The best part is that you don’t have to remove any complicated engine parts. If you follow these steps, at the end of this article you will know how to clean pistons without removing them.

1. Gather the required cleaning and safety materials

How To Clean Pistons Without Removing Them [CHEAP]

Before you start cleaning your pistons without removing them, you will need some cleaning and safety materials. I usually use the Gumout carbon cleaner that I order from I have used it 4 times so far and I am very satisfied with both the price and the results.

Not sure about you, but I always use gloves when working on my car. I usually get these vinyl gloves from The carbon cleaner can cause damage to the skin, so please make sure to wear gloves.

2. Remove the plastic cover

How To Clean Pistons Without Removing Them [CHEAP]

In order to gain access to the PCV vacuum hose, you will need to remove the plastic cover. The plastic cover can be either secured with clamps or screws. Remove the plastic cover and safely store it. Be careful not to lose any bolts that might fall inside the engine bay.

3. Locate the PCV vacuum hose

How To Clean Pistons Without Removing Them [CHEAP]

There are usually two PCV vacuum hoses located in the engine bay. One of those PCV vacuum hoses goes to the mass airflow sensor and the throttle body. The carbon cleaner can damage those components and we need to be careful not to flush any carbon cleaner into that hose. You need to locate the one that goes directly to the intake manifold and then the combustion chamber as shown in the picture above.

4. Insert the carb cleaner straw into the vacuum hose

The PCV vacuum hose might be secured with a clamp. Remove the clamp and insert the carb cleaner straw and reinstall the PCV vacuum hose as shown in the photo above. If the vacuum hose is loose on its own, you can secure it with a clamp.

The idea behind this is to spray the carb cleaner into the PCV vacuum hose that leads directly to the combustion chamber where the pistons are located and remove any carbon buildup.

5. Start the engine

Start the engine and keep the revs at 2000 RPMs. At this point, you should be careful when working because the engine will get how. Also, make sure that you are performing this task in a well-ventilated garage, or outdoors.

The engine has to be running because we need the carb cleaner to travel from the PCV vacuum hose into the intake manifold and from there into the combustion chamber. Once the carbon cleaner reached the combustion chamber, it will come into contact with the pistons and will clean them without the need of removing them.

6. Spray the carbon cleaner

With the engine running at 2000 RPMs, spray the carbon cleaner into the PCV vacuum hose that leads to the combustion chamber. With short sprays, make sure to use at least half the can for good results.

Personally, I always use the full can. This is because I really have no idea how much carbon buildup I have on my pistons. Also, the carbon cleaner is cheap, and using the full can will save you a lot of money on repairs.

7. Reattach the PCV vacuum hose and go for a test drive

After you finish spraying the carbon cleaner, remove the cleaner straw from the vacuum hose and reinstall it. Then, reinstall any covers that you might have removed in the process.

Take your car for a test run to make sure that no carbon cleaner is left in the engine. If you have followed all of the steps, at this point, you should have cleaned your pistons without removing them.

How Do Pistons Work?

When combustion occurs in the engine, the fuel changes its state of matter from liquid to gas. This causes the gas to expand or explode extremely fast. The energy created from these explosions is what allows your car to run.

Pistons are the components of the engine that harness the power from combustion. So, how do pistons work? A piston is a plunger-like component of a car engine that moves up and down in a cylinder. A typical piston has a four-stroke internal combustion cycle.

The first step in the combustion cycle is the intake stroke. This is where the piston is pulled down and creates a vacuum in the valve and is pulling air and fuel down into the cylinder.

The next step in the combustion cycle is the compression stroke. In this part of the combustion cycle, the piston is forced back up the valve. The piston is now compressing the air and fuel very rapidly. This sudden increase in pressure heats up the air & fuel mixture making it more volatile. The spark plugs light the gas on fire creating an explosion in the cylinder leading into the power stroke.

The power stroke is the next step in the combustion cycle. It converts the explosive energy to mechanical energy by forcing the piston back down, it turns the crankshaft and propels the car forward.

The last step in the combustion cycle is the exhaust stroke. The piston is being forced back upward by the exhaust stroke. In this part of the combustion cycle, the piston expels the leftover gas through the exhaust valve. Then the whole combustion cycle repeats.

Piston rings ensure that there is a seal between the piston and the cylinder. If the contact is not solid, fuel may not be being used efficiently. Some signs your Pistons may be in need of service are white or gray exhaust smoke, excessive oil usage, loss of acceleration power, and overall poor driving performance.

Igor Iwanowski

I am a certified Automotive Service Excellence (ASE) mechanic since 2018. I specialize in Brake systems, dashboard warning lights, EGRs, general engine problems, EVAP and Emissions issues.

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