Don't let the diesel filter lose its filtering function

At present, some engine operators have a wrong perception. They always think that the diesel added to the diesel engines they use has undergone a long period of sedimentation and has passed through three filters, so it is very clean. Therefore, the fuel filter on the diesel engine is dispensable. They do not seriously familiarize themselves with the structure of the filter. During maintenance, they do not carefully disassemble, inspect and maintain it. As a result, the diesel filter on the vehicle becomes ineffective. The diesel passes through the short circuit and does not pass through the filter element at all, causing the three precision pairs of the diesel engine, especially the fuel system, to wear out sharply and resulting in unnecessary losses.

It should be pointed out that even if diesel has undergone sedimentation and filtration before being added to the diesel engine fuel tank and is clean, during the refueling process, due to factors such as refueling tools, refueling environment, and unclean fuel tank openings, diesel can still be contaminated. Moreover, during the operation of the diesel engine, impurities deposited in the fuel system and suspended sediment in the air can also cause diesel contamination. Therefore, the diesel filter on the vehicle is indispensable. Besides, diesel is not necessarily truly clean before being added to the fuel tank.

The following is a brief introduction to the structure of common diesel filters and the problems that are often overlooked during disassembly, assembly, inspection and maintenance.

I. Typical Structure of Diesel Filters

At present, domestic diesel engines mostly use paper diesel filters that are simple in structure, small in size, light in weight, have good filtration effect and low cost. The paper filter is mainly composed of a stainless steel filter, a shell made by stamping steel plates and a paper filter element. The oil inlet of the filter cover is connected to the fuel transfer pump, the oil outlet is connected to the fuel injection pump, and the return oil pipe joint is connected to the fuel injection pipe. There is also an air release plug on the cover. Inside the paper filter element assembly is a round barrel with many small holes punched, and the outside is surrounded by folded special filter paper. Both ends are sealed and glued together with cover plates. After entering the filter, diesel passes through the filter paper and accumulates in the filter element barrel. Then, it flows from the fuel outlet to the fuel injection pump. The impurities and moisture accumulated at the bottom of the casing are discharged by the oil drain plug at the lower part of the casing.

Ii. Several Issues that are easily overlooked during Maintenance

Some users, when maintaining diesel filters, lose the upper and lower sealing rubber gaskets and the oil cover of the filter element. As a result, diesel does not pass through the filter element for filtration but flows into the inner cavity of the filter element without resistance through the gap between the filter element and the filter cover, causing the diesel filter to lose its filtering and purification function.

Some users reverse the position of the tray and spring of the diesel filter or even throw them away, leaving the oil inlet and outlet holes on the diesel filter cover open. As a result, the diesel cannot be filtered and directly enters the fuel injection pump.

When someone was maintaining a diesel filter, after disassembling the filter, they found that the inside and the filter element were particularly clean without any impurities or moisture, and thus believed that the diesel used was very clean. Little do they know that this is an illusion, caused by the loose material and overly large micropores of the filter paper in the filter element. At this point, the filter paper has never played a filtering role at all. If during use, it is found that the three precision pairs of the diesel engine's fuel system, especially the plunger pair, are severely worn, it may be caused by inferior filter elements. When encountering such a situation and it is temporarily impossible to purchase a new qualified filter element, the following temporary remedial measures can be taken. Use 3 to 6 high-quality napkins, fold them into paper blocks that are 0.5 to 1.0mm wider than the height of the filter element. Then, roll the folded napkins into a round bucket, ensuring that they can be inserted through the inner hole opening of the filter element cover plate. After inserting the round poke, slowly rotate both ends of the paper roll. The rotation direction should be opposite to the tightening direction of the paper roll to loosen the paper roll and make the napkin tightly adhere to the inside of the filter element. Finally, seal the cover plates at both ends. The next time you maintain it, replace it with a qualified filter element.