W108 Models

This page is dedicated to information specific to w108 models. In particular, the 250S, the 250SE, the 280S, the 280SE, and the 3.5 and 4.5 liter variants of the 280SE.

The 250S & 250SE

The 250S and 250SE were the first 108-chassis vehicles produced by Mercedes-Benz in Stuttgart. The car replaced the older “Fintail” W111 Mercedes. The front had very similar styling to the earlier 111 chassis – in fact, the headlights are identical between the two – but the engine displacement was increased, the instrument cluster redesigned with traditional round gauges, and the rear given a sleek rounded-off-fin makeover.

Without seeing the trunk badge, the 250S and 250SE are usually identifiable (a lot can change in the 40+ years since it left the factory) by their clean look; beehive or bullet turn indicators next to the grille for US models, no DOT side marker lights, only one side mirror, and inside, lack of front seat headrests, a simpler dash, usually no A/C, and manual windows. If they are still wearing their original 14″ steel wheels, they should have inner caps and outer chrome beauty rings, as opposed to the later one-piece hubcaps as seen on the newer models.

M180.920, showing York A/C compressor

Introduced in the mid-60s as Mercedes Benz’s entry-level car, the 250 came in two major versions – the 250S which was carbureted, and the 250SE, which used Bosch’s mechanical fuel injection system that was actually modified from the diesel engines. Both 250 models had a 2.5L cast-iron inline 6-cylinder engine.

The 250S
Chassis designation: 108.012
Engine type: M180.920
Built: 74,677
130 HP
0-100km/h in 13.0s
Dual carb 2.5L M180 with SOHC, front and rear disc brakes.

The 250SE

Otis Blank’s euro model 250. ©OtisBlank.com

Chassis designation: 108.014
Engine type: M129.980
Built: 55,181
150 HP
0-100km/h in 12.0s
Mechanically fuel-injected 2.5L M129 with SOHC, front and rear disc brakes.

The 280S & 280SE

Built from 1967 to 1972, the 280 came with a 2.8L (2778 ccm), Cast-Iron M130 Inline 6-Cylinder engine featuring a single overhead cam. The M130 came in both twin-carb (280S) and mechanically fuel-injected (280SE and long wheelbase 280SEL) versions.

The 280S
chassis 108.016
93,666 built
140 HP M130.920
0-100km/h in 12.0s
Dual carb 2.8L m130 with SOHC, vented front disc brakes starting on chassis 75176, and rear disc brakes.

The 280SE
chassis 108.018
91,051 built
160 HP M130.980
0-100km/h in 10.5s
Mechanically fuel-injected 2.8L m130 with SOHC, vented front disc brakes starting on chassis 81819, and rear disc brakes.

The 280SEL
chassis 108.019
8,250 built
160 HP M130.980
0-100km/h in 10.5s
Mechanically fuel-injected 2.8L m130 with SOHC, vented front disc brakes, and rear disc brakes. The SEL featured an extra 4″ of rear legroom (and a 4″ longer wheelbase).

The 280SE 3.5 & 280SE 4.5

The 3.5

The Mercedes-Benz W108 and W109 vehicles equipped with the 3.5L SOHC cast-iron block m116 V8 were produced, starting in late 1969, with the 300SEL 3.5. The 280SEL 3.5 was released in mid-1970, with the 280SE 3.5 following shortly thereafter. The 3.5 was a breakthrough in engine technology for Mercedes-Benz. With a 9.5:1 compression ratio and a redline of 6800 RPMs (unheard of in American V8s of the era), this 3.5L engine equipped with Bosch D-Jetronic EFI produced 200-230HP (estimates vary by source). Even on the conservative side, that equated to 57HP per liter of displacement, while giving nearly 17MPG on the highway. This was also unheard of by American V8 standards.

The 108 and 109 chassis Mercedes Benz vehicles with the 3.5 are some of the most in-demand vintage Benzes to this date. Their popularity is driven by the draw of the 3.5L m116 V8 that can rev up to 6800RPMs and sustain that RPM longer than any pushrod engine, in combination with the classic styling of the 108/109 chassis. Although the 4.5 had more power and torque, it did in fact have a lower redline. Combined with a taller rear-end gear ratio and a 3-speed automatic compared to the 4-speed auto found in the 3.5, the 3.5 seems faster than the 4.5 – although the 4.5 is, in fact, slightly quicker off-the-line and has a slightly higher top speed due to its gearing. The 3.5 owners say their cars are more responsive due mostly to its gearing and higher-revving engine.

The Mercedes-Benz W108 and W109 vehicles equipped with the 4.5L SOHC cast-iron block m117 V8 were produced, starting in early 1971, with the 280SE 4.5. The 4.5 engine was released by MB initially for the North American market, to get around the tougher emissions standards without killing the engine output and performance of the 3.5L engine. The m117 4.5 is very similar to the 3.5, with a 30mm taller stroke. The heads were also given larger combustion chambers, lowering compression to 8.8:1 or 8.0:1, depending on engine variation and production date. Power was 230HP or 200HP, depending on compression. The D-Jet EFI system was tuned further for the 4.5, with a specific ECU that gave a 10% full-throttle enrichment. This (along with a taller rear-end gear) allowed the 4.5 to have similar efficiency to the 3.5, yet more power on full throttle. The 3.5 and 4.5 are so similar that 2.5 heads can fit directly on a 4.5 with no modification for a roughly 11:1 compression ratio!

Note: I have a whole section dedicated to 4.5 m117 performance tuning (coming soon!)

The 4.5

The 108 and 109 Chassis Mercedes Benz vehicles with the 4.5L m117 V8 engine are still, to this date, sought after by many people who owned one of these in the early 70’s (or who had a family member or friend with one of these wehicles). Also, many people who live in Europe are buying rust-free examples from the USA and shipping them back to Europe. The 4.5 wasn’t actually offered in Europe at the time, and it has perhaps a stronger following than the 3.5 in Europe.