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Replace the three filter elements of the diesel genset

Learn how to replace the three filter elements of the diesel generator set with easy to follow steps. Let’s get started!

Table of Contents

The “three filters” of the diesel genset refer to the air, oil, and diesel filters. The “three filters” are vital in the regular operation of diesel generator sets. In this article, we’ll look at how to replace the three filter elements of the diesel generator set.

What are the three filters of diesel generator sets and their functions?

1) Diesel filter

diesel filter

The diesel filter is a unique pre-filter device for internal combustion engine diesel generators. It can filter out more than 90% of mechanical impurities, colloids, asphaltene, etc., in diesel, ensuring the diesel’s cleanliness and prolonging the engine’s service life. Using a diesel filter can significantly improve the filtration accuracy and efficiency of the engine using the felt diesel filter. It can prolong the service life of the diesel filter, and the fuel-saving effect is noticeable.

2) Oil filter

oil filter

Due to the high viscosity of the oil itself and the high content of impurities in the oil, to improve the filtration efficiency, the oil filter is generally divided into three stages, namely the oil collector, crude oil filter and essential oil filter. The filter collector is installed in the front oil pan of the oil pump and generally adopts a metal filter mesh type.

The coarse filter is installed behind the oil pump and connected in series to the central oil passage. There are mainly metal scraper types, sawdust filter types and microporous filter paper types. Microporous filter paper type is primarily used now. The delicate oil filter is installed behind the oil pump and connected in parallel with the central oil passage. There are mainly two kinds of microporous filter paper type and rotor type. Rotor-type oil filter adopts centrifugal filtration without a filter element, which solves the contradiction between oil pass ability and filtration efficiency.

3) Air filter

The function of the air filter in the diesel generator set is to filter out the dust entering the cylinder air to ensure that the engine has enough clean air to mix with fuel to generate combustion. For every 1 kg/of diesel burned, the engine needs 14 kg/air. If it is not filtered, the dust falling into the atmosphere will significantly increase the wear of the cylinder, piston and piston ring. Therefore, when the diesel generator set is working, it is not allowed to use a missing or damaged air filter. The requirements for air filters are strong filtering capacity, small wind resistance, simple structure, and convenient use and maintenance.

The above functions of the three filters of the diesel generator set hope to be helpful to you. It is worth noting that the three filters of diesel generator sets must be maintained regularly. Otherwise, its function will be significantly reduced or even damaged, affecting the regular operation of the unit.

Why are these parts important for diesel generators?

Air, fuel, and oil filters are important components that play an essential role in the operation of any diesel generator.

Your diesel generator should be running at maximum generator efficiency. It is crucial to have the correct support components adequately installed and maintained within the generator.

It would help to have the proper air, fuel, and oil filters for the right generator – make sure you only use genuine parts for your diesel generator.

When properly maintained, the life expectancy of a diesel generator can be extended by more than 20 years. In the long run, this can save you a lot of trouble and thousands of dollars.

How often should the three filter elements of the diesel generator set be replaced?

Let’s see how often the three filter elements of the diesel generator set, i.e. diesel filter, oil filter, and air filter, need to be replaced.

  1. The diesel filter must be replaced after the diesel generator set has been running for 400 hours. The replacement cycle also depends on the quality of the diesel. If the quality of diesel is poor, the replacement cycle needs to be shortened.
  2. The oil filter must be replaced once the diesel generator has been working for 200 hours.
  3. Replace the air filter according to the instructions. If the air quality in the area where the diesel generator set is used is poor, the air filter replacement cycle should also be shortened.

The above is the general situation of replacing the three filter elements of the diesel generator set. Still, the replacement cycle is also different according to the usage time of the region.

how to replace the generator set fuel filter

How to replace the generator set fuel filter?

Replacing the generator set’s filter element is an inevitable maintenance work. Some users want to replace it themselves but don’t know how. Here’s how to replace the generator set fuel filter:

The procedure for replacing the generator set filter is as follows:

  1. Unscrew the generator set’s combination casing and filter element, and discard the filter element.
  2. Fill the generator set filter with clean fuel.
  3. For the filter of the equipment generator set, tighten it by hand until the gasket stops when it touches the filter head, and then tighten it half a turn and 3/4 turn.

During this process, be sure to pay attention to the tightening of the tool. Otherwise, the filter head of the generator will be broken. Next is the process of replacing the filter element of the generator set:

  1. Turn on the generator’s oil drain switch to drain the fuel’s turbidity and sediment inside.
  2. Loosen the nut on the top of the fuel generator filter of the generator set, drain the dirt, then clean the generator filter housing and install a new filter element.
  3. Install the new gasket of the generator set on the generator filter, and install the filter element of the filter housing. Tighten it with a wrench, and then fill the generator filter cover with clean fuel to accelerate the fuel supply when the generator set engine starts.
  4. Check for leaks at the connections on the genset filter head.

How to clean and replace the diesel generator air filter?

The function of the air filter is to filter out the dust and impurities in the air and suck the clean air into the cylinder to reduce the wear of the piston connecting rod group, the valve train and the cylinder.

Let’s see how to clean and replace the diesel generator air filter.

After the air filter of a diesel generator set is used for some time, the filter element will become dirty, and the intake resistance of the filter will also increase. When the air intake resistance of the air filter increases above 625 kpa, the diesel engine will not get enough air supply, resulting in black smoke from the exhaust in advance and insufficient power.

Users can judge whether the air filter is clogged by observing the air resistance indicator installed on the intake pipe behind the air filter. That is, if the indicator window of the air resistance indicator changes from green to red under normal conditions, it indicates that the intake resistance of the filter exceeds the limit value and needs to be cleaned or replaced. When the air filter is clogged, stop the engine immediately to clean or replace the air filter core, and then reset it according to the rubber plug at the end of the wind resistance indicator. The filter element can be cleaned as follows.

  1. Tap the air filter end cap lightly to shake the accumulated dust on the filter.
  2. Open the dust collection tray’s dust outlet to let off the accumulated dust.
  3. Open the filter end cover and pull out the filter element.
  4. Block both ends of the filter element with a clean cloth or rubber plug, and then use dry compressed air with a pressure not more significant than 0.2~0.3Mpa to blow the surface of the filter element along the direction of the filter element or outward from the filter element.

Note: It is not allowed to wash the air filter element with oil or water; the vortex tube is fixed to the sleeve and cannot be disassembled. When cleaning, it can be cleaned with hot alkaline water and then blown off with compressed air; the internal filter element of the heavy-duty air filter cannot be cleaned.

The air filter (external) element must be replaced when the following problems occur.

  1. The air filter (outer) element is damaged.
  2. After the cleaned filter element is installed, the intake resistance indicator will display red again.
  3. The cleaning frequency of the filter element reaches five times.

Replace filter

  1. Loosen the wing nuts securing the bottom cover to the filter housing, and remove the filter cover.
  2. Pull the filter element off the center bolt.
  3. Remove the gasket on the outlet end of the filter.

When installing the filter, make sure the filter is seated on the gasket on the outlet end of the air cleaner.

how to replace the oil filter in a diesel generator set

How to replace the oil filter in a diesel generator set

A diesel generator set is a specialized project that requires specialized care and maintenance. One way to ensure it’s always running to peak standards is to change your oil filter regularly.

The frequency of changing the oil filter depends on the size of the generator.

You should shut down the engine and allow time for the lubricating oil to return to the sump before changing the filter.

  • Remove the cover nut and lift off the filter body cover.
  • Inspect the “O” ring for damage and replace it if necessary.
  • Remove the rotor assembly from the spindle and wait for the oil to drain from the nozzles before removing it from the filter body. Hold the rotor body firmly and remove the rotor knurled nut. Separate the rotor cover from the rotor body. Remove the center riser.
  • Use a wooden utensil to clean the sludge from the inside of the rotor cover. Make sure to wipe it down.
  • Clean and rinse the center riser with an approved solvent – make sure the filter holes are not clogged.
  • Clean the nozzle with a brass wire to ensure the oil passes smoothly and freely. Check the top and bottom bearings in the rotor body – they should be free from damage and excessive wear and tear.
  • Completely reassemble the rotor. Tighten the cap nuts to 9.5 Nm – 10.8 Nm (7-8 lb-ft.).
  • Check the spindle journals carefully – they should not damage or wear excessively. Then remove only the shutoff valve plug from the filter and shutoff valve assembly. Ensure the spring and shuttle are intact and there is no obstruction to movement. Check the gasket and replace it if damaged or worn. Reassemble the shutoff valve assembly.
  • Completely reassemble the filter. It is essential to ensure that the rotor assembly can spin freely. Now, replace the filter cap and tighten the cap nut.
  • Turn on the engine and check all connections and fittings for leaks with the engine running.

General Precautions

When changing filters, keep the following in mind:

  • Always make sure the engine is off.
  • Please check that the diesel generator is off via the control panel, emergency button and battery isolator.
  • Diesel engines generate so much suction that almost anything nearby, like nuts and bolts, can fly into the engine.


So this is how to replace the three filter elements of the diesel generator set. If you still need clarification, you can call a local professional to do this for you. Also, keep in mind to read the user manual of your diesel generator set and follow any special instructions to replace the three filter elements of a diesel generator set successfully.


BISON is a reputable and leading gensets manufacturer specializing in designing, manufacturing and supplying diesel and other generator sets. If you are looking for quality diesel generators, contact us today.

Replacement of Diesel Genset Filter Element FAQ

While running your generator without an air filter connected may be tempting, never try to do so. Doing so can cause permanent damage to the engine.

Oil is vital to your generator set as it not only circulates lubrication through the engine’s moving parts but also improves fuel efficiency and prevents deposits and sludge. Oil filters are also used to keep the engine clean like fuel filters.

Most diesel engines have two fuel filters: the first filter is located on the fuel line between the tank and the engine, while the second filter is usually found near the engine.

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