What are the faults caused by a damaged crankshaft check valve?
1 Answers
The cause of failure in a damaged crankshaft check valve is the blockage of the check valve spring. The function of the check valve and the types of ventilation systems are as follows: Function of the check valve: The check valve is a component of the crankcase ventilation system, installed inside the engine, and its role is particularly crucial. Any malfunction can affect the normal operation of the engine. During normal engine operation, a portion of the combustible mixture and exhaust gases leaks into the crankcase through the gaps between the piston, piston rings, and cylinder wall. These high-temperature gases carry fuel molecules and other impurities, causing the engine oil to gradually oxidize, degrade, and dilute under high temperatures. The influx of these gases increases the pressure inside the crankcase, leading to oil leaks from seals and gaskets. Therefore, it is essential to promptly vent these gases from the crankcase. Types of crankcase ventilation systems: Natural ventilation: Natural ventilation involves installing a downward-facing exhaust pipe on the crankcase. The outlet of the exhaust pipe is designed with a slant opposite to the direction of the vehicle's movement. The airflow generated by the vehicle's motion and the cooling fan creates a certain vacuum at the exhaust pipe outlet, drawing out the gases from the crankcase. Fresh air enters the crankcase through the intake pipe. Both the intake and exhaust pipes are equipped with filters to prevent external dust from entering the crankcase and to block the escape of oil mist from the crankcase. Forced ventilation: One end of the check valve is connected to the valve cover, as the valve cover interior is connected to the crankcase, and the crankcase pressure is directly reflected in the valve cover. The other end of the check valve is connected to the intake manifold. During engine operation, the pressure in the intake manifold is lower than that in the valve cover, creating suction that draws excess gases from the valve cover into the intake manifold, which are then sent to the combustion chamber. At the top of the crankcase, there is a pipe connected to the air cleaner, serving as the crankcase intake pipe, forming a closed loop for the forced ventilation system.
