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How to Remove Air from Diesel Generator Oil Circuit

Jan. 06, 2020

What is the impact of air entering diesel generator set?

If there is air in the diesel generator fuel system, the diesel generator will be difficult to start or flame out easily. The air has great compressibility and elasticity. When there is a leakage point in the fuel pipe from the fuel tank to the diesel engine's fuel pump, air will leak into the pipeline, thus reducing the vacuum in this section of the pipeline, weakening the suction of the fuel in the tank, and even breaking the flow, resulting in the engine unable to start. In the case of less mixed air, the oil flow can still be maintained and delivered to the fuel injection pump by the oil pump, but the engine may be difficult to start, or it will stop automatically shortly after starting.

When the amount of air mixed in the oil circuit is a little more, it will cause the number of cylinders oil to be cut off or the fuel injection amount will be significantly reduced, making the diesel engine unable to start at all.

The fuel supply system of the diesel generator set is divided into a low-pressure oil circuit and a high-pressure oil circuit. The low-pressure oil circuit refers to a section of oil line from the fuel tank to the low-pressure oil chamber of the injection pump, and the high-pressure oil line refers to a section of oil line from the plunger cavity in the high-pressure pump to the injection nozzle. In the supply system of the plunger pump, there will be no air infiltration in the high-pressure oil circuit, and there will be leakage points, which will only cause the leakage of fuel. Find a way to plug the leakage points.

In daily operation, the problem of air entering the oil circuit often occurs. So how to remove air in oil circuit of the diesel generator to make the genset return to normal operation in such a situation?

diesel generator set

Methods to remove air from diesel generator oil circuit under different circumstances

1. Use a screwdriver or wrench to unscrew any of the exhaust screws on both sides of the fuel injection pump, and press the manual oil pump with your hand until the diesel discharged is continuous, unobstructed and free of bubbles, and the diesel generator makes a "squeak" sound. Then screw the bleeder screw and press the manual oil pump back to its original position.


2. If you don’t have a suitable screwdriver or wrench on hand to open the bleeder screw on the fuel injection pump during operation, you can first unscrew the hand fuel pump, and then loosen any pipe joints from the diesel filter to the fuel injection pump, and then press the hand oil pump repeatedly until the smooth, bubble-free oil flow is discharged from the joint, then press the hand oil pump to tighten the joint, and then press the hand oil pump back to its original position.


3. If you do not have a wrench to loosen the joint in the pipeline, you can press the manual fuel pump repeatedly by hand. When the pressure in the low-pressure oil circuit is high enough from the diesel generator to the oil pump to the fuel injection pump, the diesel generator flows into the fuel return line from the overflow valve, and the gas in the generator set will be discharged from the overflow valve.

4. If you need to remove air from the oil circuit, you can first loosen the bleed screw on the fuel injection pump or loosen any joint between the diesel filter and the fuel injection pump, and then drive the mechanical fuel pump by starting. This leakage point will spray smooth and bubble-free fuel, and then tighten the above leakage point you loosened.

The air in the fuel system of the diesel generator set must be exhausted to ensure the normal operation of the unit. During the daily inspection, it is necessary to pay more attention to the sealing condition of the seals of the diesel genset and the wear of related components. Be careful to prevent air from entering the unit's fuel system.

How to prevent air from entering diesel generator set?

1. Check the fuel reserve of the fuel tank. If the fuel tank is empty or the fuel volume is less than 1/6 of the fuel tank capacity, the fuel in the tank will shake back and forth as the unit fluctuates. Once the fuel outlet is exposed, the air will be sucked into the oil circuit. Therefore, fuel must be replenished in a timely manner.

2. Check whether the gasket on the joint is uneven or damaged. If in doubt, replace the gasket with a new one.

3. Check whether the fuel hose is aging or damaged; whether the connection between the fuel pipe and the joint is loose. If there is a problem, replace it with a new one immediately.

4. Check whether the tappet of the oil pump is worn, whether the piston seal ring and rubber pad of the hand oil pump are damaged or not. If these parts are badly worn or damaged, the oil system simply sucks air. Therefore, if there are problems with these components, should correct or replace with new ones in time.

The above is the method of removing the air from the diesel generator oil circuit shared by Dingbo Power. If you have any questions, please send us an email: sales@dieselgeneratortech.com.

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