The oil cleaning filter (Fig. 1) is centrifugal, with a jet drive, included in the lubrication system in series

The oil supplied by the engine pump from the channel through the annular and radial channels enters under the insert 7.

From here, part of the oil through the mesh filter 6, which protects the jets from clogging, is fed to two jets 1, and the other part of the oil, passing through the holes in the insert, is cleaned of dirt in a centrifuge.

The body 3 of the centrifuge rotates due to the reactive force generated by the jet of oil flowing out of the body through two jets 1.

At an oil pressure of 3–4 kg/cm2, the housing, together with the oil contained in it, rotates at a speed of 5000–6000 rpm.

Under the action of the emerging centrifugal forces, the mechanical particles in the oil are thrown to the side walls of the cover 5 of the housing, where they are deposited, forming a dense sediment.

This sediment is removed from the housing cover when cleaning the centrifuge.

Oil filter (full flow centrifuge) ZIL-131

The purified oil, having rounded the insert 7 from above, through the radial holes in the upper part of the centrifuge body 3, the annular channel and the radial holes in the upper part of the axis 9 and the tube 18 enters the oil filter housing 21 and then into the distribution chamber of the engine block.

A bypass valve 23 is built into the filter housing 21, adjusted to a pressure drop of 0.8-1 kg/cm2.

The bypass valve is designed to pass part of the oil into the distribution chamber, bypassing the centrifuge, in case of significant wear of the engine bearings due to an increase in oil consumption.

A part of the oil may also pass through the bypass valve when starting the engine due to the high viscosity of cold oil.

The rotation of the centrifuge is checked by ear. When the engine is stopped, a serviceable centrifuge continues to rotate for another 2-3 minutes; while a peculiar sound is heard.

Cleaning of the centrifuge should be done simultaneously with changing the oil in the engine crankcase.

Previously, a coarse lamellar-slit filter was installed, included in the system in series, and a centrifugal fine filter with a jet drive (centrifuge), included in the system in parallel.

To clean the centrifuge, stop the engine and let the oil drain from the centrifuge, this takes 20 to 30 minutes.

Removing the cover of the 5th housing before the centrifuge is completely empty will cause oil to leak onto the engine.

To clean the centrifuge you need:

  • 1) unscrew the nut 15 of the casing and remove the casing 8;
  • 2) unscrew the plug 22 and insert a large beard into the hole to keep the body from rotating;
  • 3) unscrew the cover nut 14 with a spark plug wrench, remove the body cover 5. together with the nut 14;
  • 4) clean the cover from dirt deposits;
  • 5) after cleaning, rinse the cap in gasoline or kerosene
  • 6) remove the centrifuge insert 7, wash it in gasoline or kerosene;
  • 7) remove the mesh filter 6, wash it in gasoline or kerosene and blow it out; if the filter mesh is very resinous, if it cannot be cleaned, and if it breaks, change the mesh filter;
  • 8) clean the gasket 2 of the casing from dirt;
  • 9) rinse casing 8; damage to the end of the casing adjacent to the gasket 2 is unacceptable, as it leads to oil leakage;
  • 10) wash the nut 15 of the casing fastening.

Assemble in reverse order. Install strainer 6 as shown in fig. 1, ensuring its centering on the flange of the centrifuge body 3.

Before installing the casing, check that the centrifuge can be easily rotated by hand. Tighten the cover nut 15 only by hand.

It is forbidden to unscrew the nut 16 on the centrifuge shaft and remove the centrifuge body from the shaft to clean the centrifuge from dirt deposits in order to avoid damage to the centrifuge body plain bearings.

Only in case of unsatisfactory rotation of body 3 on axis 9, after removing cover 5 of the body from the centrifuge, unscrew nut 16 on the axis, remove the washers and body 3 from the axis and check the condition of the axle-sleeve assembly.

When removing the housing from the axle, measures must be taken to prevent the thrust ring of the ball bearing 19 from falling into the filter housing 21; if the bushings are clogged, wash them in gasoline or kerosene.

At the same time, it is necessary to check the condition of the holes of the jets 1. If they are clogged, cleaning must be carried out in such a way as not to damage the calibrated hole of the jet.

Install body 3 without cover on axle 9 in reverse order.

After cleaning, and final assembly, check the rotation of the centrifuge on a warm engine by ear.

In addition to cleaning the oil in the filter, the engine provides for centrifugal cleaning of oil in traps (dirt collectors) made in the connecting rod journals started shaft.

Cleaning oil in dirt collectors is especially effective during the period of running-in of rubbing surfaces. Dirt collectors should be cleaned when repairing the engine.