The engines have a mixed (pressure and splash) lubrication system

Under pressure, oil is supplied to the main and connecting rod bearings of the crankshaft, to the camshaft bearings

Oil is supplied to the rocker arm bushings with pulsating pressure through the hollow axles of the rocker arms, into which it enters through channels coming from the second and fourth camshaft bearings.

Oil is supplied to the rest of the engine parts by gravity and splashing.

To cool the oil, the engines are equipped with an oil cooler mounted in front of the radiator of the cooling system.

Oil system diagram GAZ-53, GAZ-66

The pressure drop in the lubrication system is mainly due to wear of the oil pump parts or the bearings of the crankshaft and camshaft.

If worn, the oil pump becomes noisy. To identify pump malfunctions, it must be removed from the engine and disassembled.

But disassembling the pump should only be started after checking the condition of the pressure reducing valve, as it can cause abnormal pressure in the oil system (weakened spring, jammed plunger, etc.).

To make sure that the pressure reducing valve is working properly, you need to unscrew its plug, remove the spring and make sure that the plunger moves freely in its seat, without jamming, and the spring is in good condition.

The free length of the spring must be 50 mm. The force of the valve spring when compressed by 10 mm should be equal to 4.6 kg.

When the force is weakened, the spring is replaced with a new one, since placing washers under it or stretching to increase the force is strictly prohibited.

Oil pump disassembly

  • 1. Remove the pump together with the gasket from the cylinder block.
  • 2. Remove the lower section housing with driven gear and gasket.
  • 3. Remove the oil pump lower section drive gear and gear key from the pump shaft.
  • 4. Remove the oil pump baffle with gasket.
  • 5. Remove the driven gear of the upper section of the pump from the housing.
  • 6. Remove the shaft with the drive gear of the upper section from the pump housing.
  • 7. After disassembling the pump, thoroughly rinse, dry and inspect all its parts.
  • 8. If on the partition of the oil pump a wear from the gear is found, then grind it until the traces of the wear are destroyed. If the section housings are worn out, replace the pump with a new one.

Be aware of the following when repairing.

The distance from the end of the hex shaft to the top end of the drive gear of the upper section of the pump should be 40 ± 0.15 mm.

A hole with a diameter of 4 mm for the gear mounting pin on the pump shaft is drilled to a depth of 23 ± 0.5 mm at a distance of 15 mm from the end of the gear. Elevation of the pin above the plane of the cavity of the tooth is not allowed.

When the axles of the driven gears are pressed out of the housings of the pump sections, the latter are heated to 100-120°C, and when pressed in, up to 160-170°C, and the axles are cooled in dry ice.

When pressing the axle of the driven gear into the housing of the upper section of the pump, it is necessary to maintain a size of 3 ± 0.25 mm, and into the housing of the lower section 0.5 ± 0.25 mm from the end of the housing to the end of the axle.

Assemble the pump in reverse order. When assembling the pump, you should change the paronite or cardboard gaskets of the housings (their thickness is 0.3-0.4 mm).

The use of shellac or other sealants, as well as increasing the thickness of the gaskets, is unacceptable, as this reduces the performance of the oil pump.

Before installing on the engine, the pump is filled with oil, since a dry pump at the very beginning of engine operation will not supply oil to rubbing surfaces, which will lead to scuffing and failure.

Oil pump drive disassembly (Fig. 2). Press out pin 6 of the drive gear using a 3 mm diameter punch. 1. Pull out the hexagon shaft 7 of the oil pump drive.

Chopper Actuator Assembly

  • 2. Press gear 5 of the drive with a mandrel, for which purpose install the drive housing with the upper end on the plate with a hole for the free exit of the roller assembly with the stop sleeve.
  • 3. Remove thrust washers 3 and 4 and remove roller 2 from the distributor-breaker drive housing.
  • 4. Press out the pin 10 of the thrust sleeve 11 of the drive shaft and press the sleeve.

After disassembly, wash all parts of the drive and subject it to a thorough inspection.

Assembly of the drive-breaker-distributor. Press the thrust sleeve 11 onto the shaft of the drive-breaker-distributor, maintaining a dimension of 19 ± 0.1 mm from the end of the shaft to the lower end of the sleeve.

In to the thrust bush, drill a hole with a diameter of 4+0.03 mm at a distance of 13 ± 0.15 mm from the end.

The axis of the hole in the bushing must coincide with the axis of the hole in the drive shaft of the breaker-distributor.

Chamfer 0.8 mm deep at 90˚ in a 4 mm hole on both sides.

Press pin 10 into the hole and rivet it on both sides.

Lubricate the roller assembly with clean engine oil, insert it into the breaker-distributor drive housing and try to easily rotate it by hand.

On the roller, install thrust washers, first steel 3, and then bronze 4.

Press gear 5 onto shaft 2, maintaining a gap of 0.15—0.55 mm between the ends of the gear and the bronze thrust washer.

The axis 9 of the groove on the shaft must be parallel to the axis passing through the middle of the cavity 8 on the lower end of the gear, the tolerance is ± 2˚.

Drill a hole with a diameter of 4+0.03mm, keeping a distance of 9 ± 0.15 mm from the axis of the hole to the end of the gear hub.

When drilling a hole, the roller assembly must be pressed by the end of the thrust sleeve 11 against the housing 1 of the breaker-distributor drive.

The axis of the hole must pass through the axis and the middle of the edge of the roller 7. the permissible deviation is not more than 0.1 mm.

Insert the hexagonal shaft 7 of the oil pump drive into the hexagonal hole in the end of the shaft 2 of the drive and press a pin with a diameter of 4 mm into the hole.

Rivet the pin on both sides.

Check the ease of rotation of the roller, the gap between the thrust washer and the end of the drive gear and the displacement of the middle of the cavity of the teeth of the breaker-distributor drive gear relative to the axis of the groove of the roller.

Disassembling the centrifugal oil filter. Remove the casing. Carefully remove the rotor cup by the nut, keeping the rotor from rotating.

While shaking the rotor on the axle, determine the radial clearance in the rotor bushings. A noticeable movement of the rotor indicates wear on the bushings, and the rotor must be replaced.

Remove the rotor together with the washer.

When removing the rotor, make sure that the upper thrust bearing race is not lifted with the rotor, as it may fall into the filter housing, and from there into the timing gear cover and into the engine crankcase.

After disassembling the filter, thoroughly wash all its parts in kerosene and blow it with compressed air.

Inspect jets and if clogged remove them for cleaning

Installing each jet in its own seat, as they are processed as an assembly with the rotor, therefore it is not recommended to unscrew both jets from the rotor at once.

To clean the jet, a drill with a diameter of 5 mm is inserted into its hole and, turning it by hand, removes all deposits. After that, the jet is washed again in kerosene and blown with compressed air through the nozzle hole.

When installing the jet in place, you should pay attention to the coincidence of one of the faces of the jet head with the mark printed on the rotor boss, since a violation of the location of the nozzle holes causes oil to be thrown into the rotor rotation zone, and this greatly slows down its rotation.</p >

To replace the sealing gasket of the rotor cup nut, remove the snap ring from the nut and remove the nut from the rotor cup.

Assemble the filter in reverse order.

When assembling, make sure that the seals are not squeezed out of their seats, and the filter rotor rotates freely on the axis.