We replace the oil seal with a new one if oil leaks from under the drive gear shank are detected. This is visually determined by the presence of oil drops on the outer surface of the gearbox. It should be borne in mind that if the gearbox housing is covered with only a thin film of oil without dripping (so-called oil sweating), then this is not a reason to replace the oil seal.
Attention! Unskilled actions when replacing the oil seal may lead to the need to disassemble and repair the rear axle gearbox, which is feasible only in a specialized workshop.
Removing
1. We install the car on a viewing hole or overpass (see "Vehicle preparation for maintenance and repair").
2. Drain the oil from the rear axle (see "Rear axle - checking the level and changing the oil").
3. Disconnect the cardan shaft from the drive gear flange (see "Cardan transmission - removal and installation").
4. Turn on the parking brake.
5. Using a 24 mm socket wrench, unscrew the nut of the shank flange.
6. It is possible to keep the flange from turning without using the parking brake. To do this, we insert bolts into two holes of the drive gear flange and, holding the flange from turning with a suitable tool (mounting blade), unscrew the flange fastening nut.
7. Using a two-jaw puller, we press the shank flange from the splines of the drive gear. Sometimes the flange can be removed by hand without the help of a puller.
8. Remove the washer and flange with a dirt deflector from the shank.
9. We hook the oil seal with a screwdriver and remove it from the gearbox housing.
Installation
Attention! Before installing the gland, check the condition of the cylindrical surface of the flange in contact with the gland. Often there are traces of corrosion and wear on it, which should be removed by polishing. If there is a deep groove on the surface, we press in the stuffing box so that it is offset, that is, it protrudes slightly relative to the end face of the gearbox neck.
1. We apply grease to the seating surface and the working edge of the new oil seal.
2. Light hammer blows (avoiding distortion) on the steel cage of the stuffing box or through a bushing of a suitable diameter, we press in the stuffing box.
3. We install the parts previously removed from the shank. It is recommended to replace the self-locking nut of the shank flange with a new one.
4. We hang out the back of the car (see "Vehicle preparation for maintenance and repair").
5. Disengage the axle shafts from the gears of the differential (see below, "Axle shaft - removal and installation, replacement of the stuffing box").
6. Holding the shank flange by the bolts screwed into the flange holes, tighten the shank nut with a torque wrench to 120 N.m, after which we rotate the flange by hand. The resistance to rotation must be light and uniform, the flange must rotate without jamming and clicking, otherwise the gearbox must be repaired in a specialized workshop. At the same time, we check the absence of even the slightest axial play in the shank bearings. If there is play, we increase the tightening torque of the nut by 20-30 N.m and again check the smoothness of rotation and the absence of play. It is not necessary to increase the tightening torque over 225 N.m, you can "crush" spacer bushing. If the backlash cannot be eliminated, the gearbox must also be repaired.
If tightening the nut does not increase the tightening torque and remains below the recommended minimum value (120 N.m), this means that the spacer "sank" and it must be replaced with the disassembly of the gearbox in the workshop.