Fuel filter: types, location and replacement rules
Content
The fuel equipment of any car works with very thin sections of some of its elements, designed to pass only liquids, but not solid particles or viscous gel-like substances. And she treats ordinary water extremely negatively. Everything can end with a failure and a long repair of the internal combustion engine power supply system.
Why do you need a fuel filter in a car
Filtration is used on all machines to separate pure gasoline or diesel fuel and foreign particles in suspension.
To do this, fuel filters cut into the supply line from the tank. These nodes are consumables, that is, they are replaced with new ones prophylactically during scheduled maintenance (TO).
All dirt remains on the filter element or in the housing and is disposed of with it.
Types
Enlarged fuel filters are divided into coarse and fine. But since coarse filters are usually just a plastic or metal mesh on the fuel pump intake pipe in the tank, it makes sense to consider only fine fuel filters.
The combined use of coarse and fine cleaning on the same car at first glance does not make sense. After all, large particles and so will not pass through the element of fine cleaning. The situation is very similar to the anecdotal installation of an additional small-sized door in the room for the entry of undersized people.
But the logic is still there. There is no need to clog the thin porous element of the main filter with large dirt, reducing its service life and reducing throughput, it is better to exclude them at the first stage of cleaning.
The main fuel filters can have several varieties:
- collapsible reusable, where the cleaning element itself allows repeated washing and removal of collected debris;
- disposable, in a non-separable case there is a paper or fabric filter element (curtain), assembled into an accordion to provide maximum working area with minimum external dimensions;
- with a sump in which water and large particles that have not passed the curtain can accumulate;
- high, medium and low efficiency, normalized by the percentage of the passed particles of a minimum size of 3-10 microns;
- double filtration, the return line to the fuel tank also passes through them;
- with the function of heating diesel fuel through a heat exchanger with an engine cooling system.
The most complex filters are used in diesel engines, the fuel equipment of which imposes special requirements on water, paraffins, filtration degree and air ingress.
Location of the filter device
Schematically, the filter is simply located anywhere in the supply line. On real machines, designers arrange it depending on the layout and ease of maintenance, if it is supposed to be carried out often enough.
Machines with a carburetor power system
On cars with a carburetor engine, gasoline is also subjected to coarse and fine filtration before it enters the carburetor. Usually a metal mesh is used on the intake pipe in the tank and a compact plastic filter with paper corrugation inside under the hood, at the inlet to the fuel pump.
Discussions about where it is better to put it, before the pump or between it and the carburetor, led to the fact that perfectionists began to put two at once, framing the fuel pump with them.
There was another mesh in the carburetor inlet pipe.
Cars with injection engine
The fuel injection system implies the presence of a stable pressure of already filtered gasoline at the inlet to the injector rail.
In the early versions, a fairly massive metal case was attached under the car. Later, everyone believed in the quality of gasoline, and the filter element is now located in the fuel pump housing, immersed with it in the gas tank.
The replacement time has increased, it is often not necessary to open the tank. Usually these filters are replaced together with the pump motor.
Diesel fuel system
Diesel filters need frequent maintenance and replacement, so they are trying to be placed under the hood in convenient accessibility. This is how it is done on diesel engines. They also have a return line with a valve.
Filter element replacement frequency
The frequency of intervention is set out in the accompanying documentation for the car. When using high-quality fuel, these figures can be trusted, unlike the oil and air regulations.
The exception will be cases of refueling with counterfeit fuel, as well as the operation of old cars, where there is internal corrosion of the fuel tank, as well as delamination of the rubber of flexible hoses.
On diesel engines, replacement must be done quite often, namely, every 15 thousand kilometers or annually.
How to replace the fuel filter on an Audi A6 C5
These machines are easy to use and easy to replace. You do not need to print the fuel pump flange in the tank.
Gas engine
The filter is located under the bottom of the car in the area of the rear seats and is covered with a plastic protection. The inlet and outlet hoses are fixed with ordinary metal clamps, clips were not used at that time.
The replacement procedure is the simplest, except for the need to be under the car:
- relieve pressure in the system by starting the engine with the fuel pump fuse removed, but often do without it, using a large amount of rags under the filter;
- unscrew the screws under the machine and remove the filter protection;
- loosen the hose clamps, remove them from the filter fittings and drain the remaining gasoline into the prepared container;
- unscrew the filter fasteners, remove the old one and install the new one in reverse order;
- The direction of gasoline flow is indicated on the filter housing.
You will have to work with a flammable liquid, so you need to have a fire extinguisher on hand. Do not extinguish gasoline with water.
Watch this video on YouTube
Diesel internal combustion engine
The filter is located in the engine compartment, for engines 1,9 on the left in the direction of travel below the air hoses, for engines 2,5 on the right on the engine shield at the top.
The sequence is a little more complicated:
- loosen two clamps fixing the hose fittings located closer to the motor shield;
- remove the pin and carefully shake the return valve, without disconnecting the hoses, take it to the side;
- remove the remaining two hoses, loosen the housing clamp with the screw at the bottom and pull the filter out of the large clamp;
- insert a new filter, put on and tighten the hose from the high pressure fuel pump (TNVD) on the engine;
- install the valve in place and fix the check;
- unscrew the bleed valve, put a hose with a funnel on the remaining fitting, fill it with diesel fuel and wait until air stops escaping from the bleed valve, then tighten the valve;
- put on the remaining standard hose and start the engine, gasping it to remove the remaining air, if it doesn’t work out, then don’t be zealous in trying, but remove the air by pumping.
On the 1,9 engine, for convenience, you will have to remove the interfering air hoses.
Watch this video on YouTube
TOP 5 best fuel filter manufacturers
Never skimp on filter manufacturers. It is worth using only the best and proven ones.
- German firm Man according to many estimates produces the best products. So much so that it makes no sense to take original parts.
- Bosch also does not need advertising, proven German quality, regardless of the location of the plant.
- filters It will cost less, but without a significant loss in quality.
- Delphi - conscientious execution, if you do not buy a fake product.
- Sakura , an Asian manufacturer of good filters, at the same time inexpensive, a large assortment, but, unfortunately, there are also a lot of fakes.
The list of good products is not limited to this list, the main thing is not to buy the cheapest market offers. Not only can you quickly destroy the resource of the motor, but it’s also easy to start a fire due to the low strength and durability of the hulls.
In particular, if possible, you should prefer a fuel filter in a metal case, rather than in a plastic one. So it is more reliable, including the accumulation of static electricity.