(A) abnormal sound characteristics. The most common cause of percussion piston is a piston and cylinder wall wear too much, the piston moves up and down swings occur, impact the cylinder wall and rattling. Percussion piston at low or idling more obvious, is "when, when" sound. When the temperature rises, the noise be reduced or eliminated, the biggest feature of piston slap sound.
(B) to determine the method. The engine speed is fixed percussion loudest position, contradict the cylinder wall with a screwdriver, you can hear the vibration of percussion. To determine the correct sound in which cylinder-by-cylinder spark plug with a screwdriver short to ground, the sound diminished or disappeared, then this-cylinder sound.
Engine speed, the greater the noise. After the engine temperature increases, the sound is not only not diminished, but sometimes more obvious. After the loss, the piston ring grooves or piston rings killed Songkuang issue in the cylinder "pop, pop" sound in the percussion. Cylinder wear, Songkuang rod bearings, piston rings and cylinder walls leading to the shoulder collide will issue abnormal sound. The higher the engine speed, percussion piston rings caused higher.
Analyzing the cylinder of carbon deposition caused by excessive noise of percussion
Knock Signature. Too much coke-cylinder engine deflagration, issued early burning "chatter, chatter" sound. When the engine is hot, turn off the ignition switch, and sometimes still is not easy to turn off.
Analysis of results from the phenomenon:
(L) tools can rise to the highest point from the lowest point, indicating that the gear pump is working properly, the boost pressure distributor valve, safety valve to meet the requirements.
(2) tools in the raised position can be maintained no longer sink legend pump dispenser internal leak.
(3) tools mentioned in a position to stop, then continue to improve, the emergence of tools to drop, after lifting phenomenon, the analysis considered dispenser slow return valve closed due. After further analysis of possible causes malfunction.
(3) The return valve seal ring with axial plug the hole. For these reasons, our analysis of ideas is this: the return valve in the normal state, pulled the dispenser handle, the slide valve down, when the first endless belt spool valve of the oil return passage closed, oil return quickly down under the action of the valve spring force and their own gravity, close return line, then the gear pump oil back through the distributor cylinder lower chamber, the cylinder piston move, make tools to upgrade. However, if the return valve seal ring with holes to plug, it will go back up and down the chamber isolation valve, when the valve back down this time, because the chamber volume increases, creating a vacuum, so that the oil return valve slow decline ( Severe not decline) At this point, though want lever handle, make tools to upgrade, but the return valve closed too slowly, the lower chamber of the hydraulic oil cylinder valve escape through the back, so the fuel tank under the chamber can not form a sufficient pressure, not lifting tools, only when the return valve closed tools to stop down, continue to rise. Based on the above analysis of these circumstances, we believe that the oil return valve seal ring clogged and cause a malfunction. After opening the top cover to check the situation Queshiruci to successfully exclude the oil return valve in debris removal, failure.
