The development of the first prototype dates back to the year 1937, but the Second World War caused a delay of the market introduction until 1949. While some money was to be spent on the development of a comfortable chassis, against the bad French country roads at that time, it had to be saved with the engine. Thus the performance and acceleration of the engine was very moderate, but so was the fuel consumption. The driver, limited by the performance of the engine, could never really utilize the good chassis.
How it works
The longitudinally mounted, air-cooled, opposed two-cylinder engine did not indicate thriftiness at first glance. Yet, the amount of cylinders and the modest total cubic capacity of 375 cm³ did. Underneath the crankshaft, the cam shaft was arranged, propelling the valves via push rods and rocker arms. The cam shaft housing and the cylinder heads were from light alloy, the cylinders from cast iron. The first two pictures show the flanges for the common suction tube. On top of it, in the middle, the carburettor was arranged, in front of the comparably enormous oil filler. It was supplied with fuel by the diaphragm pump, well visible in fig. 2. The fan wheel in front sucked in the cooling air, which was led alongside the cylinders, without thermal static regulation. In front, somewhat above the crank case, an oil cooler (fig. 3) was arranged. The entire cooling air process was naturally determined by appropriate sheet metal panelling, which has been removed in figures 1 and 2. At the end, the air ducts led the air either into the interior as heating or into the open air. A so-called fresh air heating as with the Volkswagen Beetle was not included in the package.
The engine had a quite individual characteristic. Its combustion chambers were somewhat half-spherical due to the non parallel valves. The spark plugs rose up into the combustion chamber in proximity of the exhaust valves. Despite for its under head cam shaft, the engine was confident with high speeds with its small stroke, but had to be supported by a relatively large flywheel for ascents. This was capable of causing, e.g. when shifting up into the second course, a slight spinning of the drive wheels, because the flywheel tried to keep the higher numbers of revolutions at the end of the first course. Sometimes frugality has advantages. The two starter facilities of the 2 CV were a case in point. For many years the car did not have solenoids. The starter was brought (mechanically) by hand to being engaged. If you take a look at fig. 2, at the centre of the fan wheel, you will recognize the alternative to the electrical start. Here, the driver might have set on the crank, provided by Citroën, because while starting the engine, the crank was almost guaranteed to disengage. Thus, a French farmer was still able to reach the next auto repair shop, in spite of defects at the battery and/or starter - or to continue driving, until also the generator gave in. Taking about the repair shop, the enormous repair friendliness of this engine should be mentioned. This was mainly due to its exposed situation. Also, the side parts could be dismantled in very short time. Cylinders and cylinder head were dismountable, without removing the engine. Removing the engine was just necessary for exchanging the crankshaft. The needle-stored piston rods of the crankshaft could not be unscrewed. The new exchange crankshaft was supplied together with the two piston rods in one piece. Due to the danger of metal chips, the crankshaft was supplied only in combination with a new oil cooler. Very old 2 CVs, from before 1960, did not have any electric motor, except for the starter. The windshield wipers were propelled by the speedometer. And for wiping while not driving, a manual turn knob was present.
Should you spot any errors on this page, please click here ...
Citroën 2 CV (engine)