If the crankcase neck is fogged up and dripping occurs, determine the condition of the oil seal, for which:
- put the car on a lift;
- clean the breather from dirt, check its condition;
- unscrew the inspection plug and check the oil level in the bridge housing; if necessary, bring the oil level up to normal;
- clean the gearbox housing neck from traces of oil and wipe dry;
- unlock the center differential and place chocks under the front wheels;
- lift the rear axle and place it on stands;
- start the engine, engage direct gear and at a speed of 90-100 km/h warm up the oil to a temperature of 80-90°C (approximately 15 minutes);
- with direct transmission engaged, at a speed of 100 km/h, determine the amount of oil flowing out in 15 minutes.
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.
The procedure for replacing the oil seal is as follows:
- drain the oil from the rear axle housing;
- loosen the rear wheel nuts, place chocks under the front wheels and lift the rear axle; release the parking brake and place the gear shift lever in neutral;
- remove the wheels and brake drums;
- unscrew the nuts securing the brake shield to the axle beam and use a pusher to remove the axle shafts from the differential box;
- disconnect the cardan shaft from the drive gear flange and move the shaft to the side;
- check the torque of resistance to turning of the drive gear with a dynamometer and remember its value;
- holding the flange with a special key, unscrew the drive gear flange mounting nut and remove the flange with the washer;
- remove the pinion seal;
- 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;
- 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 of the drive gear with a dynamometer.
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).
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 the chapter "Assembly and adjustment".
Assemble the rear axle in the reverse order of disassembly.