What are the reasons for the abnormal noise of the car timing gear

Update:02-04-2021
Summary:

The car engine makes strange noises, which is very disg […]

The car engine makes strange noises, which is very disgusting. These abnormal noises indicate that the engine is malfunctioning.
Symptoms of abnormal timing gear sound:
Timing gear abnormal noise is caused by the "coughing, coughing" rolling sound caused by poor gear fit or tooth surface peeling or unevenness. The timing gear meshing gap is too large, and when the engine is idling, the engine will make a slight "cough" sound.
The sound is more pronounced at medium speeds, and more chaotic at high speeds. If the meshing gap of the timing gear is too small, a whistling sound of metal friction will be emitted, which will increase as the engine speed increases.
The above phenomenon can also occur when the timing gear is severely worn. If you touch the valve chamber cover with your hand, you can clearly feel the tremor of your body and your hands will feel numb.


Reasons for abnormal noise of timing gear:
(1) The lubricating oil channel is blocked, resulting in poor lubrication of the timing gear, dry friction and abnormal noise; improper assembly or too thin gaskets and too small gaps.
(2) The cam timing gear assembly is skewed during maintenance and repair, and the unevenness will cause friction between the boss and the flange, and sharp metal noise will appear.
(3) The meshing gap of the gear is too large, and when subjected to impact load, the tooth surfaces collide with each other and produce abnormal noise.
(4) The machining accuracy of timing gears is low, burrs or tooth surfaces are peeled off during use, and gear pairs are in poor contact; timing gears and flange fixing bolts are loose, gears move in the axial direction, shafts and hole centers move, and gear meshes are uneven. Swing, etc. produce irregular abnormal noise during operation.
(5) The bending deformation and loosening of the camshaft in use will destroy the parallelism of the timing gear pair, resulting in premature wear and abnormal noise.


Timing gear abnormal noise troubleshooting:
If the axial clearance of the camshaft is too large, it should be repaired and adjusted according to the specified value; if the lubrication nozzle (ie nozzle) is blocked, it can be removed with a pin, but do not pierce it to avoid reducing the oil pressure.
When replacing the timing gear, it is best to replace the gear pairs in pairs and check the contact surface with red lead oil. If there is no unilateral tightness, the tooth gap meshes evenly; the distribution of contact marks is not less than 1/3 of the tooth. The length is not less than 1/4 of the tooth height, and the distance between the tooth surface contact marks and the edge is not less than 2.5mm, otherwise adjustment or repair should be made.
When removing the timing gear, be sure to crank the crankshaft by hand to align the ignition timing marks on the timing gear pair to avoid incorrect installation of the engine ignition device.

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