Symptoms
Metal on the drain-plug magnet, a growl that changes with road speed, a hub that runs hot, or a hub that has been run low on oil. One Expedition Portal owner says U1300L portals weren't designed for constant 100 km/h running or larger tires.
The fix, step by step
- Strip the portal box following the 435 repair manual, then clean and inspect the gears and casing.
- Replace the bearings, seals and wear rings as a set.
- Some owners fit the stronger bearings from U1550L/SEE portals, with roller bearings in place of the ball bearings, but that needs matching gears and wear rings.
- Reassemble, refill with GL-5 gear oil and monitor the temperature against the other hubs for the first few drives.
- In an emergency, one owner reports filling a failed portal with grease to limp home.
Tools & part numbers
- Full metric socket set
- bearing puller and press
- seal drivers
- torque wrench
- 435 repair manual
Where to buy the parts
Portal bearing, SBUExpedition Imports ↗Amazon ↗
Hub reduction wear ring 4353370851Expedition Imports ↗Amazon ↗
Unimog 1300/435 repair manual (OM352 / OM352A)Expedition Imports ↗Amazon ↗
Hunting a used or discontinued part? Search eBay Motors for Mercedes-Benz Unimog U1300L (435) 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.