Where Does the Exhaust Gas in the Engine Valve Chamber Come From?
2 Answers
Exhaust gas in the engine valve chamber is caused by a small amount of blow-by from the piston rings. Introduction to the Exhaust Valve: The exhaust valve, also known as the oil separator or pressure control valve, is installed between the compressor outlet and the condenser inlet. Through separation, it improves the heat transfer efficiency in the condenser and evaporator. Working Principle of the Exhaust Valve: High-pressure gas from the compressor enters the exhaust valve and then flows into the guide vanes of the exhaust valve, moving in a spiral pattern along the vanes. The centrifugal force and gravity separate the lubricating oil from the working gas, which then flows down along the inner wall of the cylinder. The working gas passes through a perforated baffle and is discharged from the central pipe of the exhaust valve. The separated lubricating oil accumulates at the bottom of the oil separator and can be periodically drained or automatically returned to the compressor's crankcase using a float valve.
In my years of experience helping friends repair cars, the exhaust gases in the engine valve chamber mainly come from gases leaking out of the combustion chamber. When the piston moves up and down in the cylinder, if the exhaust gases produced by combustion are not completely expelled, they can seep through small gaps in the piston rings into the crankcase, and then the oil vapor carries them up to the valve chamber. This is why older cars are more prone to this phenomenon, especially after prolonged high-load operation, as the piston rings wear out and become more likely to leak. I've seen many cases where, if the owner neglects maintenance, accumulated exhaust gases can turn the engine oil black and thick, even forming sludge that clogs the ventilation pipes. Regularly checking the PCV valve is crucial—it helps redirect the exhaust gases back into the intake system to be burned off. If you notice oil stains on the valve cover or smell gasoline, it's important to clean or replace the parts promptly to avoid increased fuel consumption or engine overheating, as these consequences can be quite troublesome.
