DEUTZ AIR-COOLED DIESELS

305-cubic-inch (5.0L) four and a 457-cubic-inch (7.5L) six, both with 4.33 x 5.11-inch bores and strokes. Both were adaptations of existing water-cooled Deutz engines used in German military trucks— namely the four-cylinder, 80 hp F4M513 used in the Klöckner-deutz-magirus (KDM) A/S 3000 three-ton truck and the six-cylinder, 125 hp F6M513 in the KDM A/S 4500 4.5-ton truck.

Development soon centered on the four, and the prototype engine had 70 hp, which was about 10 hp less than the water-cooled unit of the same displacement. To compensate, the stroke was increased by 10 mm (.39-in.), which increased displacement to 323 cubic inches and boosted it to 75 hp. About 1,000 engines of this type were produced despite pernicious Allied bombing and severe damage to the Deutz factory. Some of those engines were used in the RSO/03 light-tracked military cargo vehicle built by Magirus for a short while in 1944 and a small-but-unknown number were used in KDM A/S 3000 trucks.

The war ended for KHD when they were largely knocked out by bombing and the Allies advance through their area. Though many of KHD’S factory buildings were destroyed, they managed to save a fair bit of tooling and were able to resume general manufacturing late in 1945 under the direction of the Allied occupation government. They returned to building their prewar F1M414, 11-hp tractor in 1946 and gradually ramped up engine and tractor production. The air-cooled diesels went back into production around 1949 and were used in a variety of ways, including a new line of tractors that debuted for 1950.

Deutz Air-cooled Diesels

We were unable to find a model-by-model, year-by-year history of Deutz engines, so what follows are the highlights. The first post-war Deutz air-cooled engine was the 514 series. It had a 4.38-inch bore and a 5.52-inch stroke, displacing 81.2 cubic inches per cylinder. It was modular and offered in one- to fourcylinder inline arrangements from 14 to 90 hp at 2300 rpm. They continued to produce these well into the 1960s. For 1953, the smaller 612 engines were introduced with one or two cylin

This dandy little rig carried the first Deutz engines into battle. The Raupenschepper Ost 03 (Tracked-tractor East, RSO/03) was a 1.5-ton cargo vehicle designed for the Eastern Front, where challenging terrain often called for tracked vehicles. This was the third iteration of it, and each was extremely popular and useful. The air-cooled Deutz engine was well liked because of the simplicity of operating it in a frigid climate. Pappenheim

 One of the earliest postwar Deutz diesel variations was the 612 series. This is a F1L612 most likely from a ‘50s era Deutz tractor, and it made 11 hp at 2100 rpm from a 3.54 x 4.72-inch bore and stroke. This series engine differed from the norm by having a fan integral with the flywheel rather than belt driven on top. You can see the ducting on the side of the cylinder that comes up from the bellhousing. This engine is dated 1957, and from what we can tell from the sparse available literature, this engine series was made from 1953 through 1958.

W Here is a five-cylinder Deutz F5L912 from the late 1970s. The old Audi TV ad from the ‘80s said, “Four is too small and six is too bulky.” That’s when the American public was introduced to five-cylinder engines, though Mercedes had been offering five-cylinder car diesels since ‘74. A five is inherently smoother than a four, almost as smooth as a six, and the extra cylinder adds about 25 percent more power without much weight or space gain. These engines were commonly seen in Iveco trucks and certain Grumman step vans.

W The 912 series, introduced in the late ‘60s and still in production today with a lot of updates, seems to be the sweet spot in the aircooled market. While it had many updates from the first 514 series, it was still based on that original design. Shown is a F4L912 four-cylinder, but 912s have many inline cylinder arrangements. The block is deep skirted with five main bearings and the crankshaft has plenty of support.