The way to remove air in oil circuit of diesel generator set

by Generator D. Diesel Generator

These days some users ask me about air in oil circuit of diesel generator set, they do not know how to solve it. Now Starlight Power shares the way to remove air in oil circuit. Hope it is helpful to you.


If diesel generator set is difficult to start, or shut down soon after starting, it can be judged that hat the air is mixed in the oil circuit, and the air in the oil circuit will bring a lot of obstacles to the operation, which will make the generator set difficult to start or shut down.


The main reason of air mixed in oil circuit is that at least one of the injector needle valve pairs of diesel generator is worn and the seal is not tight, which makes the combustion gas channeling through the injector into the oil return system, resulting in a large amount of gas in the oil return system.

Shangchai generator set


After occur this, if return oil of injector is directly return to fuel tank, the direct impact on the operation of diesel generator set is relatively small. But if the return oil of the injector is connected to the fuel filter, it will have a serious impact on the operation of the diesel generator. Therefore, after occur this problem, should first check all injectors, and repair or replace needle valve couple.


How to find the leakage point in the pipeline and stop it?

The fuel supply system of diesel generator can be divided into low pressure oil circuit and high pressure oil circuit. The low-pressure oil circuit refers to the oil circuit from the fuel tank to the low-pressure oil cavity of the fuel injection pump, and the high-pressure oil circuit refers to the oil circuit from the plunger cavity of the high-pressure pump to the fuel injection nozzle. Here we talk about leakage point in low pressure oil circuit.


The following is the method to determine the leakage point of low pressure oil circuit.

Method 1: Exhaust the air in the oil circuit and find out the leakage of diesel oil after starting the engine.

Method 2: Loosen the bleed screw of the engine fuel injection pump and pump oil with the manual oil pump. If it is found that the bleed screw begins to discharge a large amount of bubble oil flow, and the bubble still does not disappear after repeated hand pumping, it can be determined that there is a leakage point in the negative pressure oil circuit from the oil tank to the oil delivery pump. The pipeline should be taken down, then the pressure gas should be introduced and placed in the water to find out where the bubble is.


In addition to the problems of the pipeline, the various gaskets at the pipeline joints will also leak due to improper installation, deformation, aging and damage, and become leakage points. Before the detailed inspection of the pipeline, these nodes should be inspected first.


How to remove air in oil circuit of diesel generators?

1.Routine Method

Use a screw driver or spanner to loosen any air release screw on both sides of the fuel injection pump for several turns, continuously press the manual oil pump by hand until the diesel oil is discharged, and there are no bubbles and squeaking sound.Then tighten the bleed screw and press the manual oil pump back to its original position, as shown in Figure 1-1. The exhaust method of unit pump oil system is shown in Figure 1-2.

Remove air in oil circuit


2.Non-routine method (emergency case)

1)If you don't have a suitable screw driver or wrench to open the bleed screw on the fuel injection pump, you can turn on the manual oil pump first, then loosen any connection from the diesel filter to the fuel injection pump, then repeatedly press the manual oil pump to the joint to discharge the unobstructed and bubble free oil flow, then press the manual oil pump while tightening the joint, and finally press the manual oil pump back to its original position.

2)When there is no wrench to loosen the pipe joint, the manual oil pump can be pressed repeatedly, unit the oil pressure of the low-pressure oil circuit between the oil transfer pump and the injection pump is high enough, the fuel flows into the fuel return pipeline from the relief valve, the gas in the oil circuit will be discharged from the overflow.

3)If you need to exhaust the air in the oil circuit, you can first loosen the bleed screw on the injection pump or loosen any connector between the diesel filter and the injection pump. Then start the driving mechanical oil pump, the leakage point will spray out the fuel without bubbles.   At this time, tighten the loosen the above leakage point to exhaust the air.


If air is mixed in the oil circuit of the diesel generator set, the air will affect the operation of the diesel generator set, so regular inspection and maintenance is very necessary, and the air in the oil circuit should be found and remove in time.


Starlight Power is as one of leading manufacturer for diesel generator set in China, having focused on high quality product for more than 45 years. Mainly product covers Cummins generator, Volvo, Perkins, Yuchai, Shangchai, Deutz, Ricardo, Weichai, Doosan, MTU, Wuxi etc. Power range is from 20kw to 3000kw. All product has approved CE, ISO certification. If you have purchasing plan this year, welcome to contact us by email or call us +8613481024441. We will be with you at any time. 

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About Generator D. Senior   Diesel Generator

111 connections, 2 recommendations, 677 honor points.
Joined APSense since, September 11th, 2017, From Jiangsu, China.

Created on Mar 4th 2021 18:41. Viewed 255 times.


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