Repair Procedures for 700kW Diesel Generators 2

This article continues to introduce the repair procedure for 700kw diesel generator components.

Crankshaft and Flywheel Assembly

The main damages to the crankshaft include: journal wear, cracks and fractures of the crankshaft, and ablation caused by bearing burnout. If the out - of - roundness of the crankshaft journal exceeds 0.05mm, the crankshaft journal needs to be ground. For a crankshaft with severe bearing burnout, since its metallographic structure has changed, it is generally not recommended to use it again. A crankshaft with cracks must be scrapped; otherwise, it may break.

Warning: The installation of the crankshaft and flywheel assembly must be carried out personally by the engineering director, following the correct torque and correct steps. The main bearing cap screws must be re - checked.

Cylinder Head and Valve Train

1.Cylinder Head

Cracks are likely to occur at the joint plane between the cylinder head and the cylinder block, the valve guide holes, the valve seat circular holes, the injector holes, and the cooling water jacket walls. Visual inspection and hydraulic pressure tests can be used for inspection. When the joint plane between the cylinder head and the cylinder block is uneven, it is recommended to repair it on a grinder, with a processing amount of about 0.10mm each time and a processing limit of 1.00mm. If the injector copper sleeve leaks or is damaged, it will cause water leakage, and the injector copper sleeve should be replaced. A cylinder head with cracks is recommended to be scrapped; otherwise, it will cause water leakage.

2.Valve Train

1.Valve Seats and Valve Guides

The valve seats and valve guides of some units need to be ground. The grinding amount must be correct; otherwise, it will cause problems such as valve - piston collision, valve and valve guide seizure, and a sharp increase in oil consumption. This work must be carried out personally by the engineering director.

2.Valve Springs

Check the length and elasticity of the valve springs. A too - soft spring will cause valve bounce, which will intensify the wear of the valve and the valve seat, and also disrupt the valve timing, leading to valve - piston collision. Unqualified springs must be scrapped.

3.Grinding of Valves and Valve Seats

Use grinding paste to grind the valves to make the valves and valve seats have linear contact. After all the valves are ground, the grinding paste must be cleaned thoroughly (especially pay attention to cleaning the grinding paste inside the valve guides).

4.Valve Upper and Lower Covers

Check for cracks. Unqualified ones must be scrapped.

5.Camshaft

Check for cracks, pits, corrosion, and scratches at the cam profile and journal of the camshaft. Check for cracks, tooth breakage, or tooth surface pits on the gear. Unqualified ones must be scrapped; otherwise, it will cause problems such as black smoke emission, power loss, and the risk of punching through the cylinder block.

6.Cam Followers

Check if the outer diameter of the follower shaft exceeds the standard. Unqualified ones must be scrapped. Check for pockmarks on the roller surface, whether it rotates flexibly, and if it is excessively worn. Unqualified ones must be scrapped. Check if the roller pin and the pin hole are excessively worn. If they exceed the standard, they must be scrapped. Check for cracks on the follower arm. If there are cracks, it must be scrapped.

Warning: The cam followers are the most critical and prone - to - problem parts and need special inspection; otherwise, it will cause problems such as black smoke emission, power loss, and the risk of punching through the cylinder block and breaking the crankshaft.

7.Valve and Injector Pushrods

Check if the ball - end is excessively worn, if the pushrod is out - of - round, and if it is bent. Unqualified ones must be scrapped.

8.Rocker Arms

Check for cracks, wear, or damage on the contact convex surface with the T - shaped pressure plate, and if the inner diameter of the rocker arm bushing exceeds the standard. Check the wear of the rocker arm shaft. If it exceeds the standard, it must be scrapped.

T - shaped Pressure Plate

Check if the diameter of the T - shaped pressure plate hole exceeds the standard, and if the threads of the T - shaped pressure plate are worn or damaged. Unqualified ones must be scrapped.

Dingbo Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to [email protected] we will pay highly attention on your question.