How to clean exhaust valves without removing head?
- Author: SPELAB Mechanical Engineer (focusing on car modification for 10 years)
The exhaust valves are a very critical component of an engine’s respiratory system, as they control the flow of gases. They open up to allow the exhaust gases to move out of cylinder, thus, making it possible for the fresh air and fuel mixture to accumulate in the cylinder. The valves are engineered with regard to the extreme conditions of the combustion chamber. But, with time, carbon buildup clogs these exhaust valves, thus disturbing the flow of the gases and eventually the performance of engine.
Significance of clean exhaust valves
To understand the importance of clean exhaust valves, focus on your own respiratory system. Block your nose and mouth and don’t let the inhaled air move out. You will notice a change in your capacity. Slowly start exhaling some of the air and observe the changes in your body. Same is the case with an engine. If it cannot breathe out properly, it would lack in performance as well as can be a bring up safety hazard. 
It therefore becomes very important to clean the valves because with bad valves your vehicle’s breathing is affected and it would show the following signs
- Poor engine performance
- Starting issues
- Misfiring
- Different noises
Types of cleaning
By now, you would have noticed the importance of cleaned valves for an engine. For cleaning the valves, we can use one of two different methods. The first method is mechanical cleaning, which requires disassembling the engine head, removing the valves, cleaning them with proper equipment and then assembling the engine. This mechanical cleaning requires a technical expert because assembling the engine is a daunting task and one can damage more if he is not an expert. The Second method is chemical cleaning, which is a simpler method and anyone can use that for their engines. In chemical cleaning you do not need to open the engine, instead with the help of chemical take the dirt away from the engine.
There are several types of chemicals available in the market which are used for cleaning the valves. Some chemicals contain detergents that help to break down and dissolve carbon deposits, while other contain solvents (chemicals) that can react with the carbon to break it down. There are also some solvents which can dissolve carbon deposits and help flush them out of engine. The chemical cleaning methods can be performed in two ways based on the application of the chemicals
- Spraying the chemical into the intake manifold
- Adding a chemical directly into the fuel tank
Spraying the chemical into the intake manifold
This process of cleaning the valves is very simple and can be performed by yourself at your home. You just need to spray the chemical into the intake manifold while your vehicle is running. Following are the steps you need to carryout to clean your exhaust valves.
- Turn on your engine and let the engine reach the optimal operating temperature which is around 200 degrees Fahrenheit for most of the vehicles. This can also be checked from your dashboard temperature gauge.
- Wear protective equipment, like gloves and glasses. As we are using chemicals, it can expose us to different health related hazards and therefore, to be on safe side a safety kit is recommended.
- Select a chemical cleaner among different brands available in the market.
- Remove the air filter cover and the air filter pipe connecting the air filter housing to the throttle body.
- Locate the Mass air flow sensor and spray the chemical cleaner past mass air flow sensor and empty the can. It is important to note that if mass air flow sensor sensed the chemical it will give an error code on the ECU, therefore one should spray it past the sensor as mentioned.
- Keep the engine running between 2000-4000 rpm throughout the process.
- At times you might feel the engine is stalling but keep pushing the pedal at that time.
- After you are over with spraying, reassemble your air intake system and your vehicle is good to go.
Adding a chemical directly into the fuel tank
This process is rather the easiest one. One just needs to empty a can of chemical into the fuel tank and sit back and relax while the magic happens by its self. When this chemical comes into combustion chamber along with fuel, the chemical properties of this additive helps in breaking and dissolving the carbon, thus making our engine clean. It is recommended to repeat this process more frequently to keep your engine clean as well as to improve the life of your engine and keep it away from building the amount of dirt for which mechanical cleaning is inevitable.
Conclusion
It's essential to recognize that these chemicals do not serve as a replacement for consistent care and cleaning of the exhaust valves. They are not a substitute for regular care and maintenance, but they can help your engine run better and last longer. It's always better to speak with a mechanic or other expert service to assess any performance concerns or poor engine performance and prescribe the best course of action.