The existence of the most common abnormal noises in engines depends on the engine speed condition.
Abnormal noise only exists at idle or low speeds. The reasons for the noise include: too much clearance between the piston and the cylinder wall; too tight mounting of the piston pin or too tight mounting of the connecting rod bearing too much clearance between the pusher and its valve guide hole; cam profile; sometimes the starter latch is loose and the pulley is damaged (squealing visible when changing speeds).
The sound is chaotic when maintaining a certain speed, and short-term sounds occur one after another during rapid deceleration. The reasons for the noise are: the camshaft timing gear is cracked or its fixing nut is loose; the crankshaft is broken; the piston pin bushing is loose; the axial play of the camshaft is too greatd or its ring is loose.
How to judge the abnormal noise of the motor belt:
First of all, check the motor belt. If there are multiple belts in the car and you cannot determine which belt is the problem, you can start the car first and then pour water on the belt. If the abnormal noise disappears, there is a problem with this belt. and you can check. Maybe it's loose or the quality is bad.
The motor belt makes an abnormal noise. Dousing it with water will increase its viscosity, which effectively improves the viscosity of the belt. But after the water dries, the belt will return to its original state. This is the principle of belt watering.
The answers above all pose problems. On the surface this seems to “increase friction”, but in essence it is something else.
With appropriate waxing, these waxes do not insulate the belt andthe pulley but play a lubricating role. Naturally, there is no argument for improving lubrication. The friction coefficient of wax is very low. If you apply more wax, it will definitely be more slippery than without wax! The function of proper shoe polish is to improve the contact between the belt and pulley. Think of it this way: the wax helps “glue” the belt to the pulley, allowing it to transmit more power.
When you find that the belt is loose and there is no wax on hand, you can sprinkle some water on the belt to relieve the problem for a while. It's just that water dries quickly. It's not like saying: water can also increase friction, right?