Specs, fluids & service · 1955–1980
Mercedes-Benz Unimog 404 specs, fluids and service intervals
The numbers you need in the garage, on one page: spec sheet, capacities and service intervals, wheels and tires, and the parts to order. Sourced from owners, specialists and the factory; tags marked confirm in manual haven't been checked against a factory source yet.
Spec sheet
| TYPE | Unimog 404 "Unimog S" (404.1 U82, 404.0 U110) |
|---|---|
| PRODUCTION | May 1955 – 1980, Gaggenau |
| BUILT | 64,242 (1,791 of them 404.0) |
| ENGINE | M 180 2,195 cc I6 petrol · M 130 2,778 cc (404.0) |
| OUTPUT | 80–82 PS at 4,850 rpm (M 180) · 110 PS (M 130) |
| GEARBOX | 6 forward, 2 reverse, synchronized |
| WHEELBASE | 2,900 mm (2,670 mm on 404.111) |
| LENGTH / WIDTH | 4,925 × 2,140 mm (404.1 long) |
| WEIGHT | ≈ 2,970 kg; payload 1,500 kg |
| GROUND CLEARANCE | 400 mm (15.7 in) |
| FUEL | 2 × 60 L |
| TIRES | 10.5-20 (275/80R20) on 9.00-20 |
| TOP SPEED | 95 km/h (59 mph) |
By year
| YEARS | PLATFORM | ENGINE | OUTPUT | NOTES |
|---|---|---|---|---|
| 1955–1956 | 404.111 (U82, initial series) | M 180 2.2 L I6 | 63 kW (some 59–60 kW) | 2,670 mm wheelbase, folding top. 1,210 built, 578 of them the initial series; the first 1,100 went to the French army. |
| 1956–1980 | 404.112 / .113 / .114 / .115 (U82) | M 180 2.2 L I6 | 60 kW (some 68 kW) | 2,900 mm wheelbase main series. The 404.114 alone accounts for 50,321 trucks: folding top, chassis-cab and double cab. |
| 1969–1970 | 404.117 | OM 615 2.2 L diesel I4 | 44 kW | 81 trucks for the Portuguese market. |
| 1971–1980 | 404.011 / .013 (U110) | M 130 2.8 L I6 | 81 kW (110 PS) | Closed all-steel cab from the Unimog 406, one-piece windshield. 1,151 + 520 built. |
| 1972–1980 | 404.010 / .012 (U110) | M 130 2.8 L I6 (some M 180) | 81 kW | Folding-top cab from the Unimog 416. 113 + 7 built. |
Fluids, capacities & service intervals
Assume a surplus 404 has sat for a while, and baseline everything. It has far more oil-filled places than a car: engine, gearbox, two diffs and four hub reductions, plus a steering box, an oil-bath air cleaner and a fan hub, idler and water pump that run in gear oil. The figures below are owners' charts and a translated factory schedule; confirm them in the 404 operator's manual.
| ITEM | SPEC / CAPACITY | INTERVAL | NOTES & PARTS |
|---|---|---|---|
| Engine oil & filter | 30–40W · 6.5 L (Rocky Mountain Moggers) | Every 2,500 mi, filter every second change (factory schedule); change annually on lightly used trucks | Prime oil pressure with the ignition off before starting after an oil change or three weeks' standing. Filter 000 180 00 09 (Fram CH962PL, Wix 51310 per RMM).Oil filter with gaskets (000 180 00 09) · Expedition Imports ↗ |
| Oil-bath air cleaner | 1.0 L engine oil; RMM uses 5–10W | Clean and refill every 2,500 mi, or weekly in very dusty conditions | A lighter oil reduces the intake vacuum, according to RMM.Air filter element 000 094 31 04 · Expedition Imports ↗ |
| Gearbox oil | 90W (EP80/90) gear oil · 6.0 L | Check every 2,500 mi; change every 8,000 km (RMM) to 10,000 mi (factory schedule) | There are two drain plugs. Check it often: a leaking output seal empties the gearbox into the front diff without leaving a visible drip. |
| Front & rear differentials | 90W gear oil · 3.0 L each | Change with the gearbox | Too much oil in the front diff points to the transmission output seal.Screw plug, differentials and hub reductions · Expedition Imports ↗ |
| Hub reductions (portals) | 90W gear oil · 0.3 L each, four hubs | Check every 2,500 mi; change with the axles | Look for metal, tar-like oil or water. Oil on the tires means a seal is going.Hub reduction vent screw · Expedition Imports ↗ |
| Fan hub, idler pulley & water pump | 90W (EP90) gear oil, as required | Check and top up every 5,000 mi | Water in this oil means the water-pump housing seal needs replacing.Unimog 404 water pump · Expedition Imports ↗ |
| Steering box | 90W gear oil · 0.6 L | Check every 5,000 mi | Check the drop-arm tightness at the same time. |
| Grease points | Chassis grease | Every 1,000 km (RMM) to 2,500 mi (factory schedule) | Kingpins (4), front-axle drive-shaft joints (4), steering ball joints (6), transmission output ball housings (2), clutch release shaft, handbrake and lever shafts, and any PTO joints.Steering knuckle rebuild kit (if the pins are worn) · Expedition Imports ↗ |
| Spark plugs, points & timing | Plug gap 0.50 mm · points 0.40 mm, dwell 36–38 · 10–14° BTDC with EI's kit | Inspect plugs every 2,500 mi and replace every 10,000; distributor every 5,000 | Check whether you have an old-style (short-reach) or new-style (long-reach) head before buying plugs.NGK spark plug BPR5ES · Expedition Imports ↗Bosch ignition point kit · Expedition Imports ↗Bosch rotor · Expedition Imports ↗ |
| Valve clearance | Cold: inlet 0.10 mm, exhaust 0.20 mm · warm: 0.15 / 0.25 mm | Every 5,000 mi | Park facing downhill before lifting the cover, or the oil trapped on the head ends up all over the engine bay.Unimog 404 valve cover gasket · Expedition Imports ↗ |
| Coolant, thermostat & hoses | Antifreeze or corrosion inhibitor all year · capacity confirm in manual | Flush and refill at purchase; check level regularly | Hot-climate trucks benefit from the tropical radiator and water-pump pulley.Thermostat, Unimog 404 · Expedition Imports ↗404 coolant hose kit · Expedition Imports ↗ |
| Brakes: fluid, drums & hoses | Fluid type confirm in manual · pedal free play 10 mm | Check every 2,500 mi; pull and clean the drums every 5,000 mi | Pull the drums with two M10 bolts, and don't use solvent. Replace linings by the rivets.Front wheel cylinder repair kit · Expedition Imports ↗Brake hose set, 404 · Expedition Imports ↗ |
| Fuel filters, pump & tanks | Clean the fuel filter every 2,500 mi and the pump mesh every 5,000 | At purchase, then per the schedule | Drain both tanks and check for orange flakes from a peeling lining. Don't add lead substitute, which Expedition Imports says makes the flaking worse.Inline fuel filter element · Expedition Imports ↗Fuel pump diaphragm, ethanol compliant · Expedition Imports ↗ |
| V-belts | Fan 9.5 × 875 mm (Gates 11A0875) · generator 9.5 × 925 mm (Gates 11A0925) per RMM | Check tension every 2,500 mi | Hot-climate trucks with the heavy-duty cooling pulleys take different lengths.V-belts · Expedition Imports ↗ |
Capability
| Payload | 1,500 kg (3,307 lb) Design payload |
|---|---|
| Curb weight | ≈ 2,900–2,970 kg (6,390–6,550 lb) Wikipedia; the Unimog 404 Guide gives 6,393 lb empty and 9,700 lb gross |
| Fuel tank | 2 × 60 L (2 × 15.9 US gal) 404.1 |
| Ground clearance | 400 mm (15.7 in) Portal axles |
| Approach / departure | 45° / 46° Unimog 404 Guide; 42° side slope |
| Gradeability | 70% in first gear Operator's handbook figures quoted by Wikipedia |
| Wading depth | 80 cm (31.5 in) without equipment Unimog 404 Guide |
| Top speed | 95 km/h (59 mph) · 100 km/h for the 404.0 Sixth gear |
| Fuel economy | 10–14 mpg (US) Unimog 404 Guide; owners report 7–14 mpg depending on altitude and load |
| Turning circle | 42.6 ft Listed as the turning radius in the Unimog 404 Guide |
| Towing | About 1,500 kg unbraked A Steel Soldiers member's figure, not a factory rating |
Wheels & tires
| Factory tire | 10.5-20 / 275/80R20 on 9.00-20 rims (404.0 and most 404.1s) · 10-20 listed for 404.1 (Wikipedia); the Danish army spec gives 10.00 or 10.50-20 |
|---|---|
| Biggest tire · Stock | 12.5R20 (335/80R20) on 11.00-20 rims |
| Biggest tire · Modified | Up to 39.5 in bias-ply (one-off) |
Common Unimog 404 repairs
- Portal hub and axle-tube sealsDIFFICULTY 4 / 5
- Transmission output sealDIFFICULTY 4 / 5
- Wheel cylinders, shoes and brake hosesDIFFICULTY 3 / 5
- Zenith 32 NDIX carburetor and fuel systemDIFFICULTY 2 / 5
- Points, or electronic ignition in the military distributorDIFFICULTY 2 / 5
- Throw-out bearing and clutchDIFFICULTY 3 / 5 (greasing) · 4 / 5 (replacement)
- M 180 valve adjustmentDIFFICULTY 2 / 5
- Steering knuckle (kingpin) and axle bronze bushingsDIFFICULTY 4 / 5
Always confirm torque figures, fluids and capacities against the factory service manual for your VIN. See the disclaimer; some parts links are affiliate links.