Engine-related common sense inspection method for piston knocking

The knowledge of automotive engines is not fully understood overnight, and many owners will accumulate experience in slow driving. However, for some failures of engine pistons, it is necessary to understand the causes of possible problems and shorten the inspection time. service. For example, what kind of manifestation of the engine piston knocking sound and why the reasons for maintenance are all common objective knowledge to understand.

Fault phenomenon:
1. When the engine is idling, it can hear, reach, reach, and reach continuous metal knocks.
2. When the temperature of the engine is low, the sound is loud, and when the temperature rises, the sound decreases or disappears.

cause of issue:
1, piston and cylinder wall wear gap is too large.
2, connecting rod bending.
3. The piston is deformed due to tight pin assembly.
4, connecting rod bearing assembly too tight.

Method of exclusion:
1. When the engine is running at a low speed, it gradually breaks the fire test. After the fire breaks, the sound is weakened or disappeared, which is the sound of the cylinder.

2. When idling, the sound of knocking on the cylinder is obvious and clear; as the engine temperature increases or the rotational speed is above the medium speed, the sound is weakened or disappears.

3, remove the spark plug, from the spark plug hole in the cylinder to add a small amount of concentrated lubricating oil, lubricating oil injection, with the starter to drive the crankshaft to rotate a few times, so that the piston and the cylinder wall gap full of lubricating film, and then start the engine, if the start After the moment, the sound is noticeably weakened or disappeared. However, with the loss or ablation of the oil film, the sound can quickly appear, and it can be proved that the cylinder knocks.