Preventing fires

The standard wiring harness in the 2CV is dangerous. The wiring harness is attached to the air cleaner bracket with a steel clamp. This clamp has very sharp edges. After a while the clamp cuts trough the insulation. Now it is only a matter of time before the steel clamp finds a live wire. The wire will short circuit and the wiring harness catches on fire. This can be avoided by protecting the wiring harness against the clamp with a piece of rubber wrapped around the wiring harness i.e. some old inner tube.

Keep an eye on the live wire from the alternator. The nuts must be tight and the wire ends must be good. If the nut rattles loose the cable end will vibrate on the bolt. The alternator delivers a high current (30 A). If the wire isn't connected proper you will have sparks firing between the connecting bolt and the wire. This eats away the thread and the wire end. Even worse if this wire falls off and touches ground - you will short circuit the battery via the blue wire. This wire will start to glow and immediately vaporize the insulation. The wiring harness will be destroyed and you may start a fire.

Also the battery holder should be checked closely. The genuine battery has a holder for the regulator. If the battery has to be replaced there is no real reason to buy the genuine part. You can get much cheaper batteries that have a higher capacity. The holder for the regulator is missing but it is not a problem to mount the regulator in a different place. The battery may have different dimensions, so the holder doesn't fit perfect. The new battery can still be kept in place but the holder can slip up and may touch the + terminal. As the holder is connected to ground you will have a short-circuit that may start a fire. Again this can be avoided with a piece of an old inner tube that protects the terminal.

There are different reasons for the motor to catch on fire. Apparently the heating tubes cause the biggest problem, mainly the one on the passenger's side. After some years the ends of this tube fray out. So it doesn't stay in place any longer. It will slip down right onto the muffler. On a longer trip the muffler becomes very hot and will set the paper and foam tube on fire!
Once the tube is soft on each end it won't help to tape the ends or use clamps. It will fall off again. In that case better replace the tube. The universal tubes from after market sources are not good. The best choice is to use a genuine part. But be careful - you will find the genuine tube too long. Don't take the old tube as a sample - it was already too short. Make it long enough to fit proper. In addition the tube must be attached to the heater cable or the wiring harness to keep it from falling down. You can use a long cable tie for this job.

Inside the hood you will find an insulating mat. The reason for this is not only to supply nesting material for mice and marten - it also sucks in oil and fuel. After some years it will be soaked with these liquids. There is no danger as long as the surface isn't damaged. But once the surface is destroyed the mat starts to disintegrate. More or less big pieces will fall down on the transmission, the motor and the muffler. It is easy to imagine what will happen with these oil soaked pieces on the muffler. So it is better to remove the entire mat once it starts to disintegrate. The reason for this mat was to absorb noise from the motor. In my book it is more important to avoid fires than reduce the noise level just a little. And after all these mats are available as spares.

Carburetor fires are mostly caused by backfire. This will appear as a "plop" from the motor. The reason is mostly a bad adjusted timing and/or valve settings. The mixture already ignites before the inlet valve is totally closed. This will send a beam of fire back through the manifolds into the carburetor. Normally this doesn't matter. It won't set the carburetor on fire. But if this beam of fire reaches the air cleaner it might set the oil soaked foam on fire. If this happens while driving you won't realize it for a while. The motor works normal and the fire get lots of oxygen. Then the plastic air cleaner unit catches on fire, and the burning plastic is blown all over the motor. Since the reason for backfire is mostly bad tuning of the motor it can be solved very easy. Adjust the ignition and the valves regularly. This should solve the problem.

The fuel line can also cause problems. Very critical here is the connection between the fuel pump and the carburetor. As soon as the reservoir in the carburetor is full an inlet valve will close. But the fuel pump continues to pump. This will create a pressure in the fuel line. If the connection on the carburetor (less likely on the pump) doesn't sit tight, fuel will escape. You can see this at the carburetor. If it is mainly covered with dust and dirt except an area around the inlet then the tube may not be tight. The fuel line is rubber and after some years the material will harden. When the rubber is no longer flexible more cracks will start. If the fuel pump puts pressure into the line it may burst in this condition. When fuel escapes it may reach the muffler and ignite. If it doesn't ignite you still have the risk of a gas - air mixture. One spark may ignite this. If you realize there are cracks in the fuel line replace it immediately.