Symptoms
Gear oil weeping onto the brake backing plates, oil on the inside of the tires, or a hub that drains low. Rocky Mountain Moggers calls leaking seals 'the common ailment'.
The fix, step by step
- Support the axle on stands, pull the wheel and drain the hub and the diff.
- On the front, disconnect the brake hose, engage the front diff lock, then unbolt the hub from the steering knuckle (note the one shorter bolt) and pull the hub, cardan joint and shaft out together.
- The axle output seal sits behind a staked retainer; the hub input seal can be reached from the cardan side without splitting the hub.
- Expedition Imports warns that the 140 mm hub output seal has to sit 5 mm inside the housing face, not flush, or its second lip misses the wear ring.
- Refill everything with 90W gear oil.
Tools & part numbers
- Metric sockets to 24 mm
- dead-blow hammer
- seal puller and driver
- 12-ton press if you go further
- hub-reduction tool set for a full teardown. Seal sizes listed by Rocky Mountain Moggers: hub output TCM 90x120x13TC, hub input TCM 60x75x8TC, axle tube TCM 48x68x10TC.
Where to buy the parts
Seal, hub reduction output (404 337 02 60)Expedition Imports ↗Amazon ↗
Seal, hub reduction input (404 337 03 60)Expedition Imports ↗Amazon ↗
Input gasket, hub reductionExpedition Imports ↗Amazon ↗
Hub reduction tool set, 404Expedition Imports ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Mercedes-Benz Unimog 404 parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.