The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft. 1. Fault phenomena and judgment reasons

The main causes of abnormal engine noise during normal operation are as follows:

First, when the engine is working, especially when the speed changes, there is clearance fit between the crank-connecting rod mechanism and the valve train; On the other hand, improper adjustment or failure of the engine supply system will lead to abnormal engine operation. The diagnosis method starts from the above two aspects.

2. Diagnostic items and elimination methods

1) The clearance between the piston and the cylinder liner is too large, and there is a "thump, thump" knocking sound in the cylinder, especially when the speed changes suddenly or the load is low, and the noise becomes weak when the temperature rises. Remove the cylinder block and piston connecting rod group, check their wear degree, and replace the piston, piston ring or cylinder liner.

2) The gap between the piston pin and the connecting rod bushing is too large, which makes the upper part of the cylinder make a crisp crash, especially when it suddenly changes from low speed to high speed. Replace the piston pin or bushing according to the fit clearance specified in the assembly technical requirements.

3) The clearance between the crankshaft journal and the bearing bush is too large, and a dull crash can be heard at the main bearing. With the increase of load, noise and vibration increase. Remove the cylinder block, overhaul the main bearing bushing and crankshaft, and replace the main bearing bushing if necessary.

4) The clearance between crankshaft connecting rod journal and bearing bush is too large. Determine the cylinder with noise, check the fastening of the connecting rod cover, or replace the connecting rod bearing bush. If necessary, grind the crankshaft.