2CV windscreen heater duct refurbishment

The 2CV’s heater system is predictably simple:  air used for extracting heat from the engine is passed through cardboard tubes into the cabin.  As cardboard isn’t the most long lived of materials and the original ones were showing their age I purchased a set of replacements.  Thinking this would be a 15 minute job and a good one to cross off the list in order to give myself the illusion of being productive I set about replacing them.

The lower set from the heat exchangers to the diverter on the bulkhead was simple enough but when I removed the upper set from the diverter to the screen demister ducts that protrude through the bulkhead I found the end of the ducts were rusty.  This is when it became apparent that the 15 minute job was going to take somewhat longer than expected…

2CV windscreen header duct with surface rust

Going over the ducts with a wire wheel on the drill cleaned back the visible rust but as I progressed more and more of the paint came away which indicates that rust had got under it and it was only a matter of time before the tin worm had infested the whole thing.

2CV windscreen header ducts (back)

2CV windscreen header ducts (front)

After cleaning back as far as they needed to go the exposed metal was liberally treated with rust remedy prior to painting.

There now followed an extended period of cold and damp weather which meant that painting wasn’t going to be an option:  as I don’t have a walk in spray booth this would have to be done outside which meant dry weather with a temperature sufficient to allow the solvents in the paint to evaporate.

Once climatic conditions improved the ducts were painted with etch primer followed by several coats of generic car colour (satin back).

2CV windscreen header ducts etch primed

2CV windscreen header ducts painted satin black

At one point in the course of the 2CV’s history there would have been a flap mounted in these ducts and, as the tooling wasn’t changed, they still feature the holes for this.  Originally there would have been a white rubber bung in them but these had long since perished and disappeared so I acquired some 5.5mm black silicone bungs from a popular online auction site which fitted them perfectly.

2CV windscreen header ducts with 5.5mm sillicone bungs

Refitting is the reverse of removal, that’s to say the ducts fit through the bulkhead and are secured with the factory self tapping screws before the dashboard is replaced over the top of them.

2CV windscreen header duct (passenger's side)

It’s notable that, whilst the passenger’s side duct is fitted into a moulded section of the dash, the driver’s side simply has a cutout to allow it to pass through.  This is presumably because on the original left hand drive version of the car there is no duct on this side.

2CV windscreen header ducts (driver's side)

The ducts protrude through the bulkhead and have rubber grommets to seal them.2CV windscreen header ducts through bulkhead

Two months and change after starting this 15 minute job the new heater hoses were now fully fitted.

2CV header ducts under bonet