Removal, repair and installation of the GAZ-2705 oil pump
Drain crankcase oil
Remove oil sump
On the engine mod. 402 unscrew the two nuts 1 and remove the pump 2 with the receiver as an assembly.
On the engine mod. 406 unscrew the three bolts and remove the pump with the receiver assembly.
Oil pump disassembly
Oil pumps for engines mod. 402 and 406 are similar in design.
Remove the hexagonal shaft of the oil pump drive.
Remove the mesh from the receiver by folding the edges of the mesh.
Remove four bolts 3 and remove receiver 2 and baffle 1.
Remove drive gear 1 with roller and driven gear 2.
If you need to remove the drive gear from the roller, knock out the pin.
Remove cotter pin 1, washer 2, pressure reducing valve spring and plunger installed under washer 2.
Wash the pump parts with gasoline and blow with compressed air.
Inspection and repair of oil pump parts
If there is wear on the partition (cover for mod. 402), it must be sanded so that no traces of wear remain.
Inspect the hull. If it is badly worn, you need to replace the pump.
The gears in the pump housing must turn completely freely.
The pressure relief valve plunger must move completely freely in the body.
Inspect the relief valve spring. If cracks are visible on it or the coils are broken, replace the spring.
The length and stiffness of the spring are selected at the factory in such a way that the operation of the pressure reducing valve is optimal, therefore, the length and stiffness of the spring must not be changed in any way.
The length of the spring in the free state should be 50 mm, the force to compress the spring by 10 mm should be 46 N (4.6 kgf) for the motor mod. 406.
For engine mod. 402, in order to compress the spring to a length of 40 mm, it is necessary to apply a force of 43.5–48.5 N (4.35–4.85 kgf).
If the spring does not meet at least one of these requirements, it must be replaced.
Oil pump assembly
The pump is assembled in the reverse order.
When assembling the motor pump mod. 402 under the pump cover, you need to put a cardboard gasket 0.3 mm thick.
Do not install a gasket of a different thickness or use sealant, paint, etc. when installing the gasket, as this will reduce pump performance.
Install the pump in the reverse order of removal.