How to Remove Engine Deposits

Sure it's clean on the outside, but could engine deposits be robbing this car of some of its power?
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Internal combustion engines are workhorses. They allow us to drive across the country, generate electricity for our homes when the power goes out, move large areas of dirt in a single day and lots more. So it's unfortunate that the same thing that makes them work so well -- combustion -- brings with it something that can eventually hurt the engine called engine deposits.

Deposits can be caused by several different reactions inside the engine. In both carbureted and fuel injected engines, small amounts of fuel evaporate as they're sent through the fuel ports and then cling to the tiny holes they're supposed to pass through. This is just one area where deposits can build up.


In fuel injected engines, fuel is sprayed onto the intake valves and the heat from the engine can cause the fuel to dry up and create deposits on top of them. The deposits on top of the intake valves can then absorb incoming fuel and rob the engine of it. Another direct cause of engine deposits occurs in the actual combustion chamber itself when carbon deposits form as a byproduct of the air and fuel combustion. Over time, all of these deposits build up and can cause the engine to lose efficiency, rob it of power and inhibit the engine from working properly [source: Paul].

Even though the deposits are caused by only a few processes inside the engine, deposits can travel to other areas of the engine and cause problems, too. Because engine deposits build up slowly, you can go a long time without noticing they're there, but eventually they'll rob your engine of its power and can cause serious hesitation and stalling if left unattended.

Keep reading to find out what tools and materials you'll need to clean out your engine.

The tools you'll need depend on which area of the engine you're looking to remove the engine deposits from.
The tools you'll need depend on which area of the engine you're looking to remove the engine deposits from.
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Removing engine deposits may involve nothing more than pouring an additive into your gas tank or it may involve manually cleaning some parts on your engine. The tools you'll need depend on which area of the engine you're looking to remove the engine deposits from.

Most of the time, an engine deposit additive can be used to clean out areas of the engine such as the fuel injector ports, intake valves and the combustion chamber. Fuel injector ports have an opening that's about the size of a human hair, so even a clog of only ten percent can induce stalling, engine hesitation or loss of power. Combustion chamber deposits can raise the octane requirement of the engine and even cause premature fuel detonation, both of which will cost you more money in gas. Intake valve deposits can cause hesitation and stalling. To take care of all of these internal deposits all you'll need is a bottle of engine deposit additive. Many of the additive formulas you'll find at an auto repair store will take care of several issues like cleaning the carburetor or fuel injector deposits and intake valve deposits all at the same time [Source: Paul].

Another area of the engine that you may want to clean the deposits from -- and you'll have to do it manually -- is the throttle body. For this cleaning you can get a simple throttle body spray or you can do a more thorough job with a tool like an Intake Snake or another similar product. You'll need tools to remove the intake air hose, emissions hoses and any other parts directly connected to the throttle body as well. You'll probably need screwdrivers and pliers to remove the hoses and clamps. And if you don't want to purchase a product like the Intake Snake, you can use a soft-bristled toothbrush and a mild cleaning solvent; however, even a tooth brush could cause some damage to sensors inside of the throttle body [source: Allen].

The reason a tool like the Intake Snake is better than a simple spray cleaner is that some aerosol cleaners may contain a formula that's a little too strong for the insides of your throttle body. But understand that cleaning with a toothbrush or other tools in your garage may be harmful to interior throttle body walls as well [source: Allen].

On the next page, find out how to properly clean the deposits from inside of the engine and from the throttle body without causing any damage.

Cleaning out the deepest areas of your car's engine with an additive is the quickest and easiest way to remove engine deposits.
Cleaning out the deepest areas of your car's engine with an additive is the quickest and easiest way to remove engine deposits.
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Like we mentioned on the last page, cleaning out the deepest areas of your car's engine with an additive is the quickest and easiest way to remove engine deposits. Using the product is as simple as going to the store, picking up the type of cleaner you want and then following the instructions on the label. Additives will vary based on the type of engine, what they're cleaning and how often they should be used. Just make sure you follow the instructions properly.

But if you're planning to clean out engine deposits from the throttle body, prepare to get your hands dirty. You'll need to remove the emissions hoses, intake air hose, sensor wires and anything else connected to your car's air intake. Once the throttle body is exposed it's best not to run the engine. Firing your engine at this point may set off trouble codes from the sensors and require your engine to go through all the necessary checks to correct the conditions when you run the engine the next time [source: Allen].

Use a flashlight to look inside of the throttle body and you'll likely see the engine deposits stuck on the internal walls. The problem with using an aerosol solvent to clean the throttle body is that many of these cleaners have strong chemicals to counter the fact that you won't be doing any actual scrubbing. Strong solvents can reduce the coating inside the throttle body that's there to reduce the buildup of deposits. And don't forget, it can damage sensors and seals as well [source: Allen]. Using other tools or even cleaning with a soft-bristled toothbrush may also damage some of these areas. That's why specialty tools like the Intake Snake (or others like it) are a better bet. These tools are specifically designed to clean out deposits without damaging sensitive areas.

If possible, find a pliable, plastic tool that will reach into the throttle body and allow you to clean the deposits without scratching or damaging anything. Some of these tools come with pre-soaked tips that attach to the tool. These tips have just the right amount of mild solvent and have a chemical composition that won't hurt the internal coating of the throttle body [source: Allen]. Swipe the tool around the entire inside of the throttle body until you've cleaned out all of the deposits you can reach. Once you're done, do a visual inspection to make sure you've gotten all the deposits that you can see and then replace all hoses, wires and clamps.

Looking for more information about removing engine deposits? Follow the links on the next page.

Related Articles


  • Allen, Mike. "Cleaning Throttle Bodies." May 1, 2001. (June 6, 2011)
  • Paul, Rik. "Car Care - Deposits Inside an Engine." March 1996. (June 6, 2011)