How to Judge Technical Status of Wearing Parts of Diesel Generator Set

Careful users may find that in the purchase contract of diesel generator sets, there is usually a remark in the after-sales service section: Diesel generator set wearing parts, daily use accessories, damage caused by human error, negligent maintenance, etc., all are not covered by this warranty. So what parts do the wearing parts of diesel generator sets usually refer to? How should users judge their technical state? After years of practice and exploration, Dingbo Power has summed up a set of methods for judging the technical status of the wearing parts of diesel engines. Through this method, it can basically judge whether the technical status of the wearing parts of the engine is normal and whether it needs to be replaced or repaired, so as to provide help for the maintenance of the engine.

1. Judgment of parts such as valves, cylinder liners, pistons and piston rings

The quality of the compression system directly affects the power of the engine. We use the flameout swing method to check. First remove the V-belt, start the engine, and after accelerating to the rated speed, quickly close the accelerator to the flameout position, and see the number of swings of the flywheel when it stops (counting from the first reverse swing, and one swing every time the direction is changed). If the number of swings is less than or equal to two times, it means that the compression system is poor. When the single-cylinder diesel engine is not started, the crankshaft is not decompressed and cranked. If the cranking is very labor-saving, and the compression resistance during normal cranking is not felt, it means that there are problems with the valves, cylinder liners, pistons, piston rings and other components. Remove the injector assembly, inject about 20ml of clean oil from the injector seat hole, and shake the crankshaft without decompression. If you feel that the rotational resistance increases significantly and the cylinder has a certain compression force, it means that the piston ring is sealed Sexual loss is seriously worn and should be replaced.

2. Judgment of the tightness of the injector parts

Remove the joint nut at one end of the fuel injection pump of the high-pressure oil pipe, insert the high-pressure oil pipe into the transparent glass filled with diesel oil, and press the start button to make the diesel engine idle. Observe whether there are air bubbles discharged from the high-pressure oil pipe inserted in the oil. If air bubbles are discharged, it indicates that the cylinder injector coupler is not tightly sealed and the cone surface is worn out, resulting in leakage. This method can also be used to check whether the injector is dripping oil and whether the injector needle valve coupler is stuck in the open position.

3. Judgment of whether the cylinder head gasket works

Check whether the cylinder head gasket installed on the diesel engine works by the following methods: fill the water tank with cooling water, and do not cover the cover of the water tank mouth. Start the machine at a speed of about 700 ~ 800r/min, and observe the water flow in the water tank at this time. If bubbles keep coming up, the cylinder head gasket is failing. The more bubbles, the more serious the leak. However, when the damage to the cylinder head gasket is not too serious, this phenomenon is not obvious. To this end, apply some oil around the junction of the cylinder block and the cylinder head, and then observe whether there are air bubbles emerging from the junction. Under normal circumstances, the cylinder head gasket is often considered to be unable to be used normally due to air leakage and needs to be replaced. In fact, many cylinder head gaskets are not damaged. In this case, the cylinder head gasket can be evenly baked on the flame. After heating, asbestos The paper expands and recovers, and it no longer leaks when it is put back on the machine. This repair method can be repeated many times, thereby extending the life of the cylinder head gasket.

4. Judgment of whether the cylinder liner waterproof ring works

After installing the waterproof rubber ring on the cylinder liner and installing it in the cylinder block, the water can flow into the cylinder body along the cooling water channel of the cylinder block and fill it up, stop for a while and observe whether there is water in the matching part of the cylinder liner and the cylinder block, and then assemble. A good fit should not leak at this point. Another test method is to turn off the machine after running for a certain period of time. After 0.5h, accurately measure whether the oil level of the oil pan is the same as before operation, or release a small amount of oil from the oil pan and put it in a clean oil cup. Observe whether the oil contains moisture. Generally speaking, if there is water leakage caused by the poor sealing of the waterproof rubber ring, the water seepage speed is very fast. When replacing the waterproof rubber ring on the cylinder liner, the cylinder liner should be taken out from the cylinder body first. After installing the new waterproof rubber ring, a layer of soapy water should be applied on its surface (no oil) before installation. Lubricate it so that it is well pressed against the cylinder block.

5. Judgment of valve cam wear and valve spring elasticity

Judging by the valve clearance inspection method of valve timing. First, check whether the tappet is worn and whether the push rod is bent and deformed. After these faults are eliminated, use this method to check. When checking the intake cam, first turn the flywheel to 17 degree before the top dead center of the exhaust stroke, loosen the nut, screw in the adjusting screw to eliminate the valve clearance, and lock the nut when there is slight resistance when turning the push rod with your fingers. Then check the closing time of the intake valve. The intake valve push rod can be used to determine the closing time of the valve from difficult movement to slight resistance. The degree of closing of the intake valve after the bottom dead center can be found, and the opening continuation angle of the intake valve can be calculated. If the continuation angle of the intake valve is less than 220 degree and the valve clearance at the top dead center of the compression stroke is less than 0.20mm, it can be judged that the intake cam is severely worn and needs to be replaced.

When checking the valve phase with the push rod twist method, if the critical point (slight resistance of the push rod rotation) of valve opening (the push rod is difficult to rotate) and closing (the push rod is easy to rotate) is not obvious, the valve spring can be qualitatively judged. The elasticity is too weak and needs to be replaced.

During the long-term working process of diesel generator sets, the wear, deformation and aging of parts are inevitable. How to find parts that have lost their ability to work or have abnormal technical conditions in time is of great significance to improve maintenance efficiency and reduce the incidence of failures.

We hope the above introduction will be helpful to you. If necessary, please contact Dingbo Power. Our company is a diesel generator manufacturer integrating design, supply, commissioning and maintenance of diesel generator sets. The company is committed to the long-term development of generator sets, to meet the needs of the market, with many years of sales and maintenance experience.