Unimog 404 Guide


Unimog: from the German name UNIversal-MOtor-Gerät, universal motor equipment. This is a guide to the Unimog 404, a four-wheel drive truck made by Mercedes-Benz from 1955-1980. Other Unimog models are convered, but the 404 is the focus. Topics are listed in the Table of Contents.

Contributions and Feedback

Contributions, suggestions, or corrections? Please send them to me with "unimog-faq" in the Subject field.

A note on incompleteness

Since each Unimog 404 was hand-built and could be assembled with many different options, this guide will always be incomplete. There's more standardization within the 404 series than other Unimog models since many 404s were made for different armies. Armies like all trucks of a particular model to be identical to simplify maintenance, so there were large runs of certain option combinations for particular customers. For example, the 404.117, built for the Angolan military, had an unusual 2.4l diesel engine.

Even with standardization within runs, there are many variants of the Unimog 404 with different combinations of engine, cab, cargo, and optional equipment.

A (Very) Brief History of the Unimog

This is a condensed version of the history given in G.W. Schramm's Unimog -- A German Legend.

The Unimog was built in West Germany following WWII as a hybrid farm tractor and truck suitable for gathering the harvest and bringing it to market. It was designed with some thought to military uses that would follow the eventual lifting of post-war restrictions.

The Unimog was designed to use four wheels of the same size, as opposed to the standard tractor design which uses smaller front wheels.

The first model, the U 25, was built in 1947 and had a 25hp diesel engine (Hans Feil reports that the Unimog was introduced in the town of Schwäbisch Gmünd on 10 Oct 1946). In 1950, French occupation forces made the first military order for the U 25.

In 1953, the designation changed to U 401 or U 402, depending on whether the Unimog had a short or long wheelbase.

The U 411 followed the 402 around 1956, and had at most a 34hp engine.

The Unimog 404 is an enlarged version of the 411. The 404 was produced from 1955 through 1980, with development models possibly as early as 1953. Engine variants ranged from 80-110hp from the factory, with higher horsepower possible with engine modifications.

Many Unimog 404s were sold to military groups, mainly in Europe and Africa. Known armies that have used the Unimog 404 include (then) West Germany, France, and Angola.

The Unimog 404 had the largest production run of any Unimog model. See Unimog 404: Number Built for details.

There have been several models since the 404. A partial list: U900 (406), U1250, U1350, UX100. See Unimog Models for more information.

The Many Flavors of Unimog 404

Unimog 404s come with varying engines, cabs, cargo types, factory installed options, and engine-driven implements. Common variants are listed here.

Cab options

Single cab (two doors, seats 2) or double cab (four doors, seats 6). Soft or hard top. Some hard tops have a passenger-side roof hatch.

Cargo options

Pritsche (plank bed, a drop-side cargo body with canvas top) and koffer (box). For the latter, US readers should try to picture an army's idea of a mid-size Ryder rental truck.

Box configurations included radio van (generator and inverter), ambulance, and fire engine (smaller box than radio van, water pump and storage areas for hoses and equipment). Double cab was probably only offered with a short plank bed cargo area -- 84in long, 82in wide -- with an 8 person side facing troop seat.

Engine-driven implements

There is a small list of engine-driven implements (ex: compressors, generators, and winches) that can be connected to a PTO (power take-off). This list is not complete.

Optional Equipment

There is a long list of factory-fitted options for the 404, including things like raised air intakes, tropic and arctic configurations, and soundproofing.

Here's a list of recommended Safari/tropical expedition options for the Unimog-S 404 with the M180 engine.

The most common 404 is a cargo carrier (pritsche) with a 2.2 liter gasoline engine. This was a NATO/West German Army (Bundeswehr) standard vehicle.

Since manufacture, many 404s have been customized by their owners. Diesel and camper conversions are especially popular.


This series typically comes with either a Mercedes 2.2 or 2.8l gasoline engine, with a 2.4 liter diesel being a rare variant.

The 404 came with engines capable of up to 110hp. Higher horsepower is possible by modifying the engine or swapping it with a more powerful one from a Mercedes automobile. See the Unimog 404 Engine Guide for more information.

For information on the maximum speeds of 404s, see Unimog 404 Maximum Speed.

General Specs

Most of the information in this section is from George Schramm's UNIMOG--A German Legend and Greg Trent's The Mercedes Benz Unimog .

width:           84in
length:         194in
height:          86in (cab height: 63in)
cargo bed:	118in x 78in (84in x 82in with double-cab)
wheelbase:     2900mm (114in)
turning radius: 42.6ft
empty weight:   6393lb
gross weight:   9700lb
tires:          10.5 x 20 (DOT)
fuel:           2 x 15.9 gal
ground clearance: 15.7in
  (w/o equipment): 80cm (31.5in) 
traverse angle 
  (side slope):	42 deg
approach angle:	45 deg
departure:	46 deg
climb:          70%
descent:	90%
avg mpg (gas):	10-14 (US gallons)
trans. gearing
   forward:	14.93/8.23/4.47/2.46/1.52/1.0
   reverse:	20.12/11.09

Special Features

Coil springs, 6-speed gearbox with integral transfer box and 2 reverse gears. Fully locking differentials. Four wheel drive and axle differential locks can be engaged and disengaged at any time without declutching. Dirk Rautenberg says "it's the drivetrain that makes this thing so UNIque." The Unimog gets its high (16") ground clearance through 6" portal axles, which raise the main axles well above the tires' centers.

Despite its high ground clearance, the Unimog is very difficult to roll. It can handle a 42 degree side slope. One enthusiast managed to roll a Mog, but only by driving it over a car. Name omitted to protect the guilty, but it wasn't me. Really.

Maintenance and Operation

Max speed: 59mph (under 100kph) with the 2.2l 80hp engine.

For more information on the maximum speeds of 404s, see Unimog-S 404 Maximum Speed.

Following are sections on maintaining a 404 and running it in extreme conditions.

Regular Maintenance

Here's a version Unimog 404.1 Maintenance Schedule. This was translated from the German manual, so there may be errors. Please report any inaccuracies to me.

Also, I have put together a list of miscellaneous parts with part numbers and specifications.

Brake Maintenance

See the Brake System Obervations guide for tips on brake maintenance.


See the Unimog 404 Tires guide for information on replacement wheels.

Radio and Ambulance Box Maintenance

See the section on Camper Modifications for suggestions. Also, check out the guide to Unimog box lifting for help on removing the radio or ambulance box.

Breakdowns, Towing

In the event that you need to tow a Unimog 404 that has a dead engine, the manual recommends this procedure in order to avoid damaging the transmission:
  1. Engage 2nd gear
  2. Select neutral on forward/reverse lever
  3. Do not exceed 25 mph (40 km/h)
  4. Check gearbox for overheating on long-distance tows

Hot Climate Operation

For hot climate operation, an extra fuel pump and a tropical radiator were offered as factory-fitted options. Additionally, the following fan pulley diameters maximize fan speed and water circulation flow (part numbers for all 404 models with the M180 engine, according to Microfiche SA 35464):
Description		      size	part number

Water pump front pulley       134 mm	180 200 32 05
Water pump rear pulley        115 mm	180 200 23 05
Idler pulley                  118 mm	180 200 31 05
Also, two 9.5 x 900mm V belts are used in this configuration.

Modifying a Unimog 404

Instructions for customizing a Unimog 404.

Aside from engine swaps, one of the most common conversions is to turn a radio box (kauffer) into a camper. Step-by-step overview.

Here's guide to lifting a radio or ambulance box off of the frame of a Unimog 404

Buying a Unimog 404

Unimogs are easy to find in Europe, and fairly easy to find in the US. Many S 404s have been imported to the US by individuals and independent importer/dealers who specialize in these vehicles.

US issues

This section contains information on importing older vehicles into the United States. Where possible, I have including references to applicable law.
emissions tests
Many Unimog 404 trucks were built so long ago, that they are either exempt from current emissions requirements, or subject to very relaxed requirements (the requirements in effect at the vehicle's date of manufacture).

Mark Peterson reports that in California pre-1965 vehicles do not have any smog requirements imposed on them - 1965 - 1967 vehicles are "PCV valve only".

import and DOT NHTSA laws
DOT:Department of Transportation
NHTSA:National Highway Traffic Safety Administration
Summary: vehicles manufactured 25 or more ago appear to be exempt from the many DOT NHTSA requirements. Vehicles manufactured less than 25 years ago are subject to more stringent requirements, mainly regarding bumpers and passive restraint systems. With very few exceptions, people who wish to import the more recent vehicles will have to bring these vehicles into compliance, and these modifications may cost several thousand dollars. That's assuming a DOT designated garage is willing to do the work.

The key is bringing the vehicle in compliance with the Federal Motor Vehicle Safety Standards (49 CFR 571, not for the faint-hearted).

According to the US Department of Transportation, National Highway Transportation Safety Association's web site VEHICLE IMPORTATION GUIDELINES:

As a general rule, all motor vehicles less than 25 years old, must comply with all applicable FMVSS [Federal motor vehicle safety standards] and be certified by the original manufacturer to that effect in order to be imported into the United States on a permanent basis. Federal law prohibits importation of a motor vehicle not certified as conforming to the standards, except under the conditions prescribed below. The regulations defining the requirements for importing a vehicle can be found at Title 49, Code of Federal Regulations, Part 591 (49 CFR 591), "Importation of Vehicles and Equipment Subject to Federal Safety, Bumper, and Theft Prevention Standards."

If a vehicle that is not certified to meet U.S. standards is less than 25 years old and entering on a permanent basis, it must be imported by a Registered Importer (RI) or the importer must have a contract with an RI. A vehicle imported in this manner must enter under a DOT bond. The bond will be released after the vehicle is brought into conformance with all applicable safety standards.

The document goes on to say that bringing a vehicle up to safety standards may be very expensive, and that you should consult with a Registered Importer before you try to import a vehicle. Finally, the document lists Registered Importers who specialize in European vehicles. There aren't many, and they are concentrated in California, New York/New Jersey, and Florida (none in New England, one in New Mexico). The agency also lists all Registered Importers that they know about (not just Euro specialists).

The NHTSA document doesn't contain the text of the law (49 CFR 591). For that, you can do a search from the US House of Representatives Code of Federal Regulations. Alternately, you can view the full text of 49 CFR 591 in all of its mind-numbing glory.

If you want to do the work yourself to bring the vehicle up to US specs, you must become a Registered Importer. Read 49 CFR 592 for details.

The Land Rover FAQ has a section on importing vehicles that summarizes the importing issues.

Toy Unimogs

I found some neat Unimog toy trucks by Bruder at Amazon. My favorite is the desert rescue vehicle. The others I found are: fire truck, snowplow, truck with crane and log trailer, street sweeper. One fellow says these are fairly large, sturdy plastic toys (about the size of the Tonka Dump Truck).

Further Reading and Viewing


See my collection of Unimog links.


In the US, Hemmings Motor News is the best source for Unimog advertisements. By best, I mean that it is easy to find at US newsstands and also has around four Unimog ads each issue.

Another source of the occasional Unimog advertisement is Land-Rover Owner International, a UK-based magazine. This is available from large newsstands in the US for about $8 an issue. See this section of the Land Rover FAQ for subscription information.

The German magazine OFF-ROAD has an average of 6 ads per month in the classifieds.

If you have suggestions for other newsstand publications, let me know.

There are also specialty magazines and newsletters that are harder (well, impossible) to find at newsstands. I will add these shortly.


Unimogs have appeared many films, including Congo and Wings of Desire (Himmel Über Berlin). Details.


If you own a Unimog, you will want the following: Operators Manual (Betriebsanleitung), Shop Manual (Werkstatthandbuch), and Parts Manual. These are available in English and German (and almost certainly other languages) from Buch und Bild in Germany. Many US Unimog dealers also carry the manuals.

Other books of interest are: Das Grosse UnimogBuch (lots of pictures and text), 40 Jahre Unimog (over 600 pictures, little text), and Unimog Firetrucks (Der Unimog in der Feuerwehr, two volumes, lots of pictures and modifications).

Book und Bild also carries other Unimog literature including: information on camper and diesel conversions, and the history of the Unimog.

Buch und Bild
Helma Wessel
Finkenweg 13
D-76571 Gaggenau

Fax: (within Germany) 0 72 25/47 79


Thanks to the readers of the UNi mailing list and rec.autos.4x4. Special thanks to Dirk Rautenberg, Gregory Trent, Michael Carradine, Ulf Stahrenberg, Mark Peterson, Manfred Princz, Kent Drummond, Ron Miller, Luke Miller, and Christian Falzon for their contributions.
[Unimog Links].
Patrick Tufts