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Why Is Engine Oil Fast to Deteriorate in Diesel Generator?

Apr. 09, 2020

Generally, we should change engine oil of diesel generator once time after 500 hours' operation, but sometimes the oil becomes thinner and impurities increase before the replacement period, so it can not be used continuously. Starlight Power shares some reasons with you.

Why Is Engine Oil Fast to Deteriorate in Diesel Generator?

1.The part number of engine oil is incorrect, the quality fails to meet the standard requirements. We should select the engine oil which meet CC grade or above for the diesel generator with supercharging and rated speed greater than 2000 R/min;

2.Technical condition of diesel engine generator is not good, and the blowby gas, oil, fitting clearance are too large or the oil temperature is too high;

3.Diesel generator set often operates at low temperature, low load and low speed. The piston deformation is not enough and the combustion is not complete. Diesel oil enters the oil pan along the cylinder wall to dilute the engine oil;

4.Waste gas enters the oil sump and condenses into water and acid substance, which makes the oil deteriorate;

5.Oil filter element is dirty, and unfiltered dirty oil enters into the lubricating part, which accelerates the wear of parts;

6.Sealing ring of the filter element breaks and internal leakage occurs. Part of the engine oil passes through the filter directly without passing through the filter element, which causes the engine oil to deteriorate.


Therefore, we need to prevent engine oil deteriorate.


Diesel generator

How to prevent engine oil from deteriorate? We can use 8 methods as follows:

1.Check engine oil level often

We should carry out this inspection before diesel generator starts or stops for 10min, and should check the oil level again after 10min. When replenishing the engine oil, pay strict attention to cleaning and check whether there is leakage.

2.Check engine oil quality often.

When checking the oil level, pay attention to check the pollution degree of the oil. The oil on the dipstick should not change color (except for oil blackening). When engine oil reaches the interval mileage or the oil change index, the engine oil shall be changed in time. Multi grade oil is easy to turn black when it is used, which is a normal phenomenon. The common methods to check the quality of engine oil are: oil trace comparison, viscosity comparison test and assay etc.


3.Change engine oil regularly

Although the engine oil has a prescribed oil change cycle, due to the different degree of wear and tear of diesel engine, the quality of the engine oil is different, and the different regions, climate and working conditions will affect the oil change cycle. Early replacement will cause waste, and late replacement will cause other accidents of diesel engine due to aging of engine oil.


When replacing engine oil, we should start up diesel engine until its working temperature reach normal value (above 80℃); then stop diesel engine, drain the old oil from the oil sump and the filter in the hot state. If possible, when changing the oil, it is better to use the vacuum oil change equipment, which can suck the old oil clean.

If discharged oil is dirty, we should clean the old oil in the lubricating oil passage. During operation, add 60%-80% cleaning oil (thin oil or oil mixed with 20% diesel oil) of standard capacity to the diesel engine, start the diesel engine, run it at idle speed for 3-5min (never at high speed), drain the cleaning oil and add clean new oil.


4.Select suitable engine oil

Choosing the right engine oil is an important factor to ensure the normal operation of the diesel engine, and also the fundamental guarantee to extend the service life of the engine oil. In practice, we should select engine oil according to the requirements.


5.Avoid oxidation and deterioration due to high oil temperature

Ensure that cooling system of water-cooled diesel engine works well and avoid overheating. When the cooling system is abnormal, check and eliminate it in time; ensure the crankcase ventilation device is in good condition, clean the ventilation pipe and valve regularly; keep the oil temperature at 70-80 ℃; turn on the oil radiator switch in time; keep the normal oil level.


6.Do well cleaning work

Prevent dirt and impurities from entering the lubricating system; change the oil filter regularly; clean the lubricating system thoroughly and change the oil regularly; check whether water is mixed in the oil; prevent rain, snow or other oil from entering when changing or adding the oil; repair in time when the cylinder head and the engine block are cracked, the water blocking ring of the cylinder liner is aging and invalid or the cylinder gasket is damaged; drain the water first when disassembling the cylinder head Clean to prevent water from entering the sump.

Silent generator

7.Prevent diesel oil from entering engine oil 

When the fuel supply quantity of the fuel injection pump of the diesel generator set is too large, the fuel supply pressure is too low, or the fuel injector drips and atomizes poorly, the diesel injected into the cylinder will not be fully burned, and part of it will flow into the oil pan along the cylinder wall, resulting in the thinning of the oil, the decrease of viscosity and the premature loss of lubrication. Therefore, it is necessary to regularly check or adjust the fuel injection pump and fuel injector, and timely replace the worn out plunger, oil outlet valve and fuel injector coupling.


8.Avoid oil erosion by exhaust gas in cylinder

When the fit clearance between the piston and the cylinder liner, between the valve and the valve guide is too large, the high temperature and high pressure exhaust gas in the combustion chamber will rush into the crankcase, accelerate the aging and deterioration of the engine oil, and form colloid, carbon deposit and acid harmful substances. Therefore, it is necessary to replace the above-mentioned fitting parts with excessive wear in time, restore their normal fit clearance and maintain a good sealing effect.


Starlight Power is an important manufacturer of generator and diesel generator in China, we can provide open type, silent type, mobile trailer type, container type, canopy type generator set, power range is from 20kw to 3000kw. Welcome to contact us for price and specifications.

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