Symptoms
Water spitting from tank drains, slow pressure build, sluggish locker or front-drive engagement, or a dryer that purges constantly.
The fix, step by step
- Drain the air system completely.
- Unscrew the desiccant cartridge from the dryer, oil the new seal lightly and spin the new canister on hand-tight.
- Open each tank drain until only dry air comes out, and replace any drain valve that leaks or sticks.
- Run the engine, check how quickly pressure builds, and confirm the governor cuts out and the lockers engage.
Tools & part numbers
- Strap wrench
- soapy water for leak checks
Where to buy the parts
Desiccant air dryer canister (U1300L and others)Expedition Imports ↗Amazon ↗
Air tank drain valveExpedition 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.