QSK19 series engine noise diagnosis

QSK19 series engine noise diagnosis
Note: When troubleshooting for engine noise, the first to exclude the noise caused by the auxiliary device, such as by the air compressor and power take-generated, do not mistake these noise is the engine noise. Remove the auxiliary drive belt to eliminate the noise caused by these devices. Noise will be spread to those who have no problem with metal parts. Therefore, using the stethoscope will help determine the cause of the engine noise of the position.
If you hear the noise with the crankshaft speed, engine speed changes, the noise may be related to the crankshaft, connecting rod, piston, the piston pin. If you hear the noise with the camshaft speed, engine speed changes in the half, the noise may be related to the valve gear components. Hand-held digital tachometer can help determine whether the noise to the crankshaft or camshaft speed of operation of the relevant parts.
Through the single-cylinder engine noise sometimes found to lack the fire test. Reference “QSK19 series engine fault diagnosis and repair manual” in the steps 006-005. If the noise volume decrease or disappear, then the noise and the test on a single cylinder.
Determine the source of noise is no fixed rule or test method.
Driven by the engine components and auxiliary equipment, such as gear-driven fan clutch, hydraulic pump, belt-driven charger, air conditioning compressors and turbochargers are likely to cause engine noise. The following information can be used to guide diagnosis engine noise:
Main bearing noise
Move the spindle Poisson noise can be generated by percussion with a load on the engine was heard, the sound of its large and dull. If all of the main bearings are all loose, you will hear a loud and short percussion sound. This is a pattern of percussion sound and with the speed change. When the engine load or drag heavy traffic, this is most loud noise. This rod knocking sound noise generated than dull. Low oil pressure will also produce with this situation.
If the bearing is not loose enough to produce their own separate percussion sounds, if the oil is too thin or no bearing on the oil, bush will produce percussion noise.
An irregular noise may indicate worn crankshaft thrust bearing.
Intermittent sharp knocking sound that the crankshaft axial clearance is too large. Repeat clutch clutch action may cause changes in the noise.
Connecting rod bearing noise
Excessive clearance in connecting rod can cause a variety of engine speed conditions, that is idle and load conditions of the percussion noise. When the bush began to loose, the noise may be related to piston slap or loose piston pin noise mixing. The volume of noise increases with engine speed. Oil pressure is too low will produce this situation.
Piston noise
Difficult to distinguish between piston pin, connecting rod and piston noise caused by the difference between. Caused by loose piston pin double-click percussion sound, usually you can hear the engine idling. When the noise of the cylinder of the injector to stop fuel injection, this percussion sounds obvious change will occur. However, in some engines, when the vehicle is at a steady speed when driving on the road, the percussion sound becomes more apparent.