How to repair the malfunction of the engine intake and exhaust valves

Fault 1: The valve stem is bent.

During our repair process, we occasionally encounter bent engine valve stems. This failure is mainly due to gear jumping or breakage of the transmission belt of the valve train, resulting in unsynchronized operation of the piston and the valve, resulting in collisions between the upper and lower valves of the piston, and bending and deformation of the valve rod. When encountering this fault, it is generally necessary to replace the valve and check whether the valve guide and piston connecting rod mechanism are abnormal.

Fault 2: Poor valve oil sealing performance burns engine oil.

Due to the poor sealing performance of valve oil seals, engine combustion oil failures are more common during our maintenance process. Due to excessive engine temperature in some vehicles, the main body of the valve oil seal is made of rubber, resulting in poor high-temperature performance of the rubber, resulting in reduced sealing performance and oil leakage; Some vehicles have valve oil seals that leak due to incorrect installation of valve oil seals during replacement, resulting in damage to the valve oil seals; Some vehicle faults are due to unqualified valve oil seals.

Problem 3 Excessive valve noise.

Excessive valve noise is also a frequent fault that we encounter, mainly on vehicles that require manual adjustment of valve clearance. As the engine usage time increases, we need to regularly check the valve clearance. If the valve clearance is too large, it will lead to excessive clearance between the engine valve rocker arm and the valve rod, resulting in abnormal noise.

After finding the intake and exhaust pipes, the vertical position of the intake and exhaust pipes is the vertical position of the intake and exhaust pipes. If the camshaft cover is opened. The larger the valve clearance, the smaller the exhaust valve clearance, the intake valve. If a cylinder has four or two valves, the larger one is the intake port and the smaller one is the exhaust port. If a cylinder has five valves, three small intake ports, and two large exhaust ports.

The function of the valve is to draw air into the engine and mix it with fuel for combustion; The function of the exhaust valve is to exhaust the exhaust gas after combustion and dissipate heat. Excessive valve clearance: After the intake and exhaust valves are opened late, the intake and exhaust times are shortened, the valve opening height is lowered, the normal valve timing is changed, and the power generated by the engine due to insufficient intake and dirty exhaust is reduced.

In addition, it also increases the impact force of valve train components, accelerating wear. Too small clearance: After the engine operates, parts are heated and expanded, and the valve is pushed open, resulting in lax valve closure, resulting in air leakage and power reduction, serious carbon deposition or burning of the valve sealing surface, and even valve impact on the piston. The hydraulic column valve train does not need to leave valve clearance.