Diesel generator repair training diesel engine -p16-p18 cylinder head failure

Diesel generator repair training diesel engine -p16-p18 cylinder head failure

2. Cylinder head is easy to produce faults and five

Faults that occur in the use of diesel generator cylinder heads are caused by cracks, increased carbon deposition in the cylinder head, and deformation.

If the diesel engine cylinder head cracks, it will lead to diesel engine leakage, oil in the oil pan inside the water or oil leakage; if the bottom of the cylinder cover in the combustion chamber too much carbon, diesel engine will cause overheating, power drop and fuel consumption rise After the cylinder head is deformed, the cylinder gasket is easily damaged. The area shown by the circle in Figure 2-10 is where the cylinder head is prone to failure.

3. The main reason of cylinder head damage

Causes of cracks in the cylinder head of a diesel generator set are as follows: First, uneven thickness or excessive residual casting stress occurs during casting: First, the operator is used and improperly maintained. For example: Forgetting to drain the cooling water from a diesel engine in a cold area; excessive accumulation of scale, causing localized poor heat dissipation of the engine, resulting in excessive thermal stress inside the engine; sudden addition of cold water to the tank at high engine temperatures: It was hit by a large external force.

The causes of carbon deposition in diesel engine cylinder heads are as follows: First, the diesel engine idles for a long time; second, the fuel advance angle is not adjusted according to the data specified in the technical specification; 3) the cylinder pressure is low; and 4) the injector spray The diesel fuel has poor atomization, low fuel injection pressure, no fuel injection or dripping; Fifth, the diesel engine is overloaded for a long time and overloaded with diesel.

The main reasons for the deformation of the diesel engine cylinder head are: First, there are defects in the casting: Second, the deformation is caused by high temperature during welding cracks; Third, the torque used by the maintenance personnel when tightening the cylinder head exceeds the torque specified in the technical specification. , resulting in deformation around the screw hole; Fourth, maintenance personnel in the assembly of the cylinder head, the nuts are not uniform or not in accordance with the order of tightening the fastening: Fifth, the maintenance personnel did not disassemble the cylinder head nut in accordance with the provisions of the order.

4. Cylinder head failure inspection method

The following inspection methods can be used when the diesel engine cylinder head cracks:

1 observation method. This method is suitable for checking initial cracks.

2 Conduct hydraulic test. After the cylinder head is removed from the machine body, a certain pressure must be ensured during the hydrostatic test, and it should be carried out with the scale removed. When there is no special sealing cover, you can use your fingers to block the water hole. Common tools include hydraulic presses, automotive air pumps and high pressure air cylinders. The test method is shown in Figure 2-11.

The increase in carbon deposition at the bottom of the cylinder head of a diesel generator is generally checked by observation.

After the cylinder head of the diesel generator is deformed, the following method can be used to check; place the bottom of the cylinder head up and make it in a horizontal position, and then use a ruler and feeler gauge to measure the unevenness, as shown in Figure 2-12.

5. Repair method after cylinder head is damaged

Cracks in cylinder heads of diesel generators can be bonded and welded.

The specific operation method is the same as the repair method of the body crack.

The following method can be taken when clearing the bottom of the cylinder head

The heat welding method and the filler plate bonding method are processed.

1 Use a wooden spatula for cleaning. Remove the cylinder head and put it into kerosene for cleaning. Then remove it with a wooden spatula.

2 Use organic solvents to soften and remove.

After the cylinder head of the diesel generator set is deformed, the following methods can be used for repair:

1 Use the auxiliary research method to repair.

2 Trim using grinding or milling.

6. Correct disassembly and assembly of diesel generator steam red caps

When the serviceman disassembles and assembles the cylinder head, especially when disassembling and assembling the combined cylinder head, the operator may operate in a certain order. Otherwise, the cylinder head may be deformed, resulting in undue loss.