What is the phenomenon of engine valve tappet ringing? What is the reason? How to judge

1. Phenomenon This kind of noise is rhythmic and intermittent, and the sounding part is on the camshaft side. For engines with side valves, it is more obvious to disassemble the valve cover. Tapping is a kind of crisp "click, click" sound, just like the sound of a small steel ball falling on a slate. When the engine is idling, the noise is obvious, above the medium speed, and generally weakens or disappears.

2. The deviation of cylindricity and roundness of tappets or guide holes is large, or the cooperation is lax; Because the spherical surface or cam at the big end of the tappet is worn and deformed (the cam loses its original axial inclination), the tappet does not rotate or does not rotate flexibly in the guide hole; Poor splash lubrication.

3. When checking and judging that the engine is idling, you can refer to the engine speed mid-speed test when you hear a firmer and clearer sound than the valve foot sound on the camshaft side and the "flameout" test has not disappeared. If the sound weakens or disappears, it may be the abnormal sound of the tappet.

In order to confirm the noise and determine which tappet made the noise, you can remove the valve cover and make a hook, and test the hook one by one at the adjusting bolt on the tappet. When the tappet is hooked, the sound weakens or disappears, so it can be concluded that the tappet is ringing.