15.4. OIL FILLER UNIT

The oil filter pipe of the 2CV has two functions. The first is well known, namely filling the engine with oil. The second is the venting of the crankcase. This feature is very important. In the oil filter pipe there is a kind of pressure valve in the form of a rubber ring (membrane). In the crankcase certain pressure should always be present.
The vacuum is caused by the up and down movement of the pistons. If the pistons ‘go inwards’, the pressure in the engine will go up and then the relief valve will open. If the pistons ‘go outwards’, the engine will suck up air, this will not be possible because the ring closes.
If this ring is clogged or dried out, the crankcase will suffer over pressure. This will allow oil to leak in places where the seal is the weakest, such as the crank shaft seals and the rubber seal. When a gasket or seal leaks into the engine, it doesn’t necessary mean that the gasket is the cause, it could be that a broken oil filter pipe is the cause of the leak, a lot of oil, or there is a puddle of oil in the air filter, you may then assume that the valve is malfunctioning. The only solution is to put another valve because it is not possible to repair it.

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