How to Clean Carbon Deposits From Your Engine Yourself

The best approach is to pour a special chemical decarbonizer into the cylinders through the spark plug holes to loosen and soften carbon and soot deposits. Specialists recommend doing this on a warm engine.

The second option is less work, but it is also less effective. You can add the chemical cleaner to the engine oil and/or the gasoline. In either case, read the instructions carefully: how and where to add the product, and in what amount.

Let's go through the decarbonizing procedure for your engine step by step.

First, remove the spark plugs.

Next, set the pistons to a mid-stroke position. To do this, raise one drive wheel slightly with a jack, put the car in top gear, and turn the wheel by hand. You will be able to see where the pistons are.

Now, using an ordinary syringe, carefully inject the chemical product into the engine cylinders through the spark plug holes. Use about 25 ml (about 0.85 fl oz) per cylinder. To help the product reach the piston rings sooner and start working on the carbon deposits, rock the raised wheel back and forth a few times.

After rocking the wheel, wait one or two minutes. Loosening the deposits in the cylinders takes anywhere from ten minutes to an hour, depending on the product you choose. During this time the carbon gradually turns semi-liquid. When you start the engine, it should burn off and leave the combustion chamber.

Then shift out of gear and crank the engine with the starter for about ten seconds to clear any liquid left in the cylinders. Warning: if you skip this step, the engine can be damaged by hydrolock (hydraulic shock). Keep this in mind!

To prevent ignition arcing, before cranking the engine, disconnect the high-voltage center wire from the distributor cap and secure it with a gap of about one to two centimeters (about 1/2 to 3/4 in).

Reinstall the spark plugs, lay the wire on the distributor cap, and start the car. If the engine is hard to start, don't worry. This is common after decarbonizing. You may also see smoke from the exhaust during the first few kilometers (miles) of driving.

When you are done, let the engine run for a while, and then you can drive off.