Features

Longitudinal scratch marks on the fire side and around the rim; in most cases, the rim is adhered.

Reasons

1. Long-term operation under overload conditions.
2. Insufficient coolant leads to poor heat transfer.
3. Poor lubrication, such as when the oil level is below the standard mark in the oil pan.
4. Incorrect fuel supply, injector failure, and similar issues.
5. Using low-quality lubricants and fuels leads to excessive carbon buildup, causing the rings to seize up.
Causing the piston to overheat.
6. The air entering the cylinder is not clean and contains a high level of impurities.
7. The piston cooling nozzle has malfunctioned.

Features

The skirt shows longitudinal tear marks on one or both sides.

Reasons

1. The engine block deforms, causing the connecting rods to bend and resulting in cylinder misalignment.
2. A malfunction in the cooling system leads to temperatures that are either too high or too low.
3. Improper assembly.
4. Running in improperly, yet immediately subjecting it to heavy loads.
5. Improper lubricant selection or lubrication system malfunction.
6. When the "three filters" fail, coarse abrasive particles are drawn into the cylinder, causing scratches.
7. Operating under overload or over-speed conditions.
8. Abnormal combustion caused by a fuel system malfunction led to engine overheating.

Features

Irregular scratches appear near both sides of the piston pin bore.

Reasons

1. Cooling system malfunction (e.g., failure to install a thermostat, leading to excessively low temperatures).
2. Frequent cold starts.
3. Low-temperature, over-speed, and overload exercise.
4. Run-in at low temperature and low speed for an extended period.

Features

Radial cracks along the edge of the combustion chamber.

Reasons

1. Overloading operations.
2. Incorrect fuel supply and injector failure lead to localized overheating.
3. Continuous alternating load.
4. Sulfur, vanadium, and other elements in low-quality fuel cause high-temperature corrosion, leading to…
Formation of rapid thermal cracks.
5. Boost pressure is too high.

Features

The shoreline shows abnormal damage, appearing as molten erosion.

Reasons

1. High-temperature, high-pressure gas will shear the casing, causing the annular shoulder at the break point to melt.
Damage to the seal; the ring moves up and down within the groove, causing damage to the ring land.
In severe cases, the broken ring can climb up to the top surface, leading to cylinder scoring and even damage to the cylinder head.
2. The piston is skewed to one side, causing excessive stress on the ring land on the opposite side and leading to fracture.

Features

A punctured cavity appears inside the combustion chamber.

Reasons

1. Operating under overload conditions. 2. Excessive fuel supply.
3. Foreign objects falling in.
4. Poor combustion performance. For example, if the cetane number of the fuel is too low,
Injector failure, premature fuel injection, and so on.

Features

The piston fractured and broke off below the oil ring groove.

Reasons

1. An abnormal impact caused it to fracture at the weak oil ring groove.
2. Poor lubrication leads to engine seizure and bearing burnout.
The connecting rod snapped it off.
3. After the piston head seizes in the cylinder, the piston pin snaps it apart.
4. The clearance between the relevant components is excessive, leading to impacts from reciprocating inertial forces,
Causing fatigue fracture.
5. Overloading operation.
6. Improper assembly.

Features

Broken into multiple segments with irregular fracture surfaces.

Reasons

1. Incorrect fuel supply and a malfunctioning injector lead to high temperature and high pressure.
2. Related components lose balance or become damaged, resulting in high-frequency vibrations.
3. Overloading operations.
4. Improper assembly.
5. Excessive wear on the cylinder liner or ring groove edges leads to repeated impacts.

Reasons

1. Air filter failure—filter element is substandard.
2. Poor lubrication and substandard lubricant quality.
3. Incorrect oil supply—scrubbing the tank.
4. Long-term operation at low temperatures.
5. Improper assembly.
6. Failure to perform proper break-in procedures, as well as operating at speeds or loads beyond the specified limits.
7. Using low-quality fuel.

Features

Abnormal damage or crushing of engine-related components.

Features

The fire-facing surface and top appear honeycombed or resembling pear skin.

Reasons

1. Improper adjustment of the fuel injection timing
2. The fuel injector has failed, resulting in secondary injection, oil dripping, and severe afterburning.
3. Operating beyond the load capacity.
4. Insufficient air intake.
5. Turbocharger failure.
6. Intercooler is Dirty

Features

The ends of the piston pin bore show signs of melting damage,
Deep and shallow pits have appeared on the inner wall of the cylinder liner.

Reasons

1. Improper assembly.
2. Retaining ring deformation (exceeding fatigue strength).
3. The retaining ring fails to meet quality standards.
4. Connecting rod bent.

Features

The piston has cracks or fractures along the thrust surface.

Reasons

1. Excessive clearance between the cylinder and piston leads to severe knocking.
2. The connecting rod is severely bent.
3. Rough handling at work.
4. Poor lubrication (e.g., insufficient oil level in the oil reservoir).

Features

The top surface shows marks from valve-to-valve contact.

Reasons

1. Incorrect valve timing.
2. Valve clearance is adjusted too tightly.
3. The cylinder head gasket is too thin.
4. The connecting rod bearing and journal, as well as the camshaft journal and bearing clearance, are excessively large.
5. Valve spring broken.

Features

The inner cavity appears dark red or reddish, often accompanied by symptoms such as sticky rings, melted cylinder heads, scuffed cylinders, and oil burning.

Reasons

1. Incorrect fuel supply, injector failure.
2. The piston cooling nozzle has malfunctioned.
3. Overloading operation.

Features

With, localized circumferential fractures along the Second Ring shoreline.

Reasons

1. Abnormal combustion and rough operation lead to fatigue failure.
2. Overloading operation causes excessively high gas pressure to rupture the ring land.
3. Cylinder distortion, localized ring sticking.
4. Abrasive wear increases the clearance between the ring and the ring groove, causing the cylinder liner to protrude and ultimately leading to the fracture of the ring land due to reciprocating inertial forces.

Features

Piston wear is often asymmetrical, frequently accompanied by symptoms such as oil burning, cylinder scoring, and excessive exhaust emissions.

Reasons

1. Body deformation.
2. Connecting rod bent or twisted.
3. Improper assembly.

Features

The combustion chamber and its top surface are grayish white, accompanied by oil-burning symptoms.

Reasons

Fuel is substandard.