It is not always easy to find the head gasket for a car of which few have been made.
If there is no replacement to be found, there is nothing left but to make a new gasket.
In the early days of the car, there was no provision for separating the head from the cylinder block.
The reason for that was relatively simple. They were not yet able to make a perfect seal between two parts that were exposed to so many thermal and physical forces.
The engine blocks were therefore cast in one piece complete with a cylinder head, with the water and oil circuit plus the combustion chambers.
That was certainly practical, but not very key-friendly when the maintenance had to be accessible to everyone. Techies
quickly looked for a solution to make the head dismountable and to come up with a seal for the combustion chamber and for the water and oil circuit. They came with a simple wrapping made of paper coated with boiled linseed oil. The next step? A plate of asbestos soaked in boiling linseed oil and then dried for 24 hours. The cured oil formed a protective layer. Copper then replaced the linseed oil. Over the years, the quality of the gasket has been further improved by the addition of steel, copper lead (an alloy of copper and lead) or graphite.
Another improvement was the reinforcement of the bores of the cylinder through the fitting of rings consisting of steel or copper. The asbestos gasket has at some point given way to a multi-layer sandwich made of aluminum or copper plates or a mixture of these metals.
This was before the preference was given to metal and plastic gaskets (metalloplastics) with a core of fibers and compressed elastomers (graphite, PTFE, asbestos) and a protective film of copper, stainless steel, pure iron, nickel or copper nickel on the surface.
Since the ban on the use of asbestos, gaskets have generally been made from perforated galvanized sheet steel that is enclosed in two layers of aramid fibers or in other
inorganic materials (such as minerals, metals and derivatives thereof) or in high-quality elastomers. The elastomers are there for flexibility. They are usually reinforced at the boreholes, the hottest part of the engine.
In between, quite a few people will wonder when they have such a reinforced packing in front of them on which side it should be put in place.
The answer is simple: the part that is most reinforced is always directed towards the side of the cylinder block.
Many gaskets today are remade on a semi-industrial scale by Meillor or Glaser. But if you are looking for a replacement for a non-standard model or a gasket for a particular engine (a block of a Dauphine that has gone from 850 to 904 cm3) the story changes. Then they have to be recreated. That costs something if there really is no other option.
Suppose that the dimensions and data of your gasket cannot be found, you will need a computer to draw a mold with your data. If the gasket does appear in the registers, and you only want one, then there is no problem, whether it is digitized or available in mold form, there is no technical barrier.
If, on the other hand, you want a larger number (more than ten pieces), then it is better to forget the computer (that takes too long, after all all cutouts are made piece by piece with a cutter), use a mold that is much more practical to to make large series.
Handwork is needed in any case. That takes time, a lot of time.
This story came about with one of the few remaining, artisan European makers of head gaskets and such. It is a small, French company where old-fashioned craftsmanship and a lot of skill go hand in hand with a computer. 'Tous les moteurs' now has customers throughout Europe.
www.touslesmoteurs.fr
"Tous les moteurs"
26, rue de Verdun
94500 Champigny-sur-Marne
Tel. 0155092911