Congealing of the crankcase neck and even the formation of individual drops in quantities not exceeding the specified norm are not a sign of leakage.
Determining the condition of the seal
1. Place the car on a lift or inspection pit.
2. Clean the breather from dirt and check its condition.
3. After unscrewing the inspection plug, check the oil level in the bridge housing; if necessary, top up the oil level to normal.
4. Clean the gearbox housing neck from traces of oil and wipe dry.
5. Raise the rear axle and place it on stands.
6. Start the engine, engage direct gear and at a speed of 90–100 km/h warm up the oil to a temperature of 80–900°C (approximately 15 minutes).
7. With direct gear engaged, at a speed of 100 km/h, determine the amount of oil flowing out in 15 minutes.
Replacing the oil seal
Oil leakage exceeding 5 drops in 15 minutes is a sign of a faulty oil seal.
A damaged seal can be replaced without removing the gearbox from the vehicle, if no other gearbox parts need to be replaced.
1. Drain the oil from the rear axle housing.
2. Loosen the rear wheel mounting bolts; place chocks under the front wheels and lift the rear axle; release the parking brake and place the gear shift lever in neutral.
3. Remove the wheels and brake drums.
4. Loosen the nuts securing the brake shield to the axle beam and use a pusher to remove the axle shafts from the differential box.
5. Disconnect the propeller shaft from the pinion flange and move the shaft to the side.
6. Check the torque of resistance to turning of the drive gear with a dynamometer and remember its value.
7. Holding the flange with a special key, unscrew the drive gear flange mounting nut and remove the flange with the washer.
8. Remove the pinion seal.
9. Lubricate the working surface of the new seal with LITOL-24 grease and press it with a mandrel into the gearbox housing to a depth of 2–0.3 mm between the end of the gearbox housing and the outer surface of the seal.
10. Install the flange with the washer on the drive gear and, holding it with a special key, tighten the flange mounting nut, periodically checking the torque of resistance to turning the drive gear.
11. If the initial torque of resistance to turning was 58.8 N cm (6 kgf cm) or higher, the new torque of resistance to turning should be 9.8–19.6 N cm (1–2 kgf cm) greater than the initial torque. If the initial torque of resistance to turning was less than 58.8 N cm (6 kgf cm), tighten the flange fastening nut until the torque of resistance is 58.8–88.2 N cm (6–9 kgf cm).
12. If the torque resistance to rotation is exceeded when tightening the nut, disassemble the gearbox, replace the spacer sleeve with a new one, then assemble the gearbox and adjust as indicated in subsection 5.4.7.6.
13. Assemble the rear axle in the reverse order of disassembly.