How to distinguish between engine intake and exhaust valves

After finding the intake pipe, the vertical position of the intake pipe is the intake valve. The vertical position of the exhaust pipe is the exhaust valve. If the camshaft cover is opened. Large valve clearance means small exhaust valve clearance means intake valve clearance. "If a cylinder has four or two valves, it is for intake and for small exhaust.". If a cylinder has 5 valves, 3 small intake ports, and 2 large exhaust ports. For example, Jetta 5V.

The function of the valve is to suck air into the engine and mix it with fuel for combustion; The function of the exhaust valve is to exhaust the exhaust gas and heat after combustion.

Excessive valve clearance: After the exhaust valve is opened late, the intake and exhaust time decreases, the valve opening height decreases, and the normal valve timing changes. Due to insufficient intake air and dirty exhaust, the engine power is reduced. In addition, it also increases the collision of valve train components, accelerating damage.

Too small clearance: After the engine is operating, parts expand due to heat, and the valve is pushed open and not tightly closed, resulting in air leakage and reduced power, serious accumulation or combustion on the valve sealing surface, and even a collision between the valve and the piston. The valve train of the hydraulic support column does not need to leave valve clearance.