a workshop report by CQ: "Looking at the water outlet of an Amilcar engine, I realised that a part of the flange was corroded so much, water leakage was inescapable. I managed to
buy another one; "in original condition" as the french say, but no magnifying glass was needed to see clearly 3 pinholes in a very corroded area. Contemplating about a repair, I remembered my mother; the many evenings mending my socks under a twilight
lamp, even putting a layer of wool on an already thin area. In those years after WW2, spirit revived and bachelors cried: "if there is a hole in your sock, throw them away! "Having past the bachelor state a long time ago I had to do the repair on this Amilcar part......
For peace of mind, no 2K liquid metal etc. but an "honest" repair ! For sure this water outlet will not contain exotic metals as titanium, magnesium or chrome, so it can be soldered with a so called "SOFT" aluminium solder. Its instruction has to state: "can be used for compositions containing zinc".
Usually these alloys contain for the larger part: Zn, Sn, Al and have a melting point of ± 380 C. The melting point of the water outlet however will be between 450C and 650 C.The technique is straight forward. As this part is not contamined with oil, "degreasing" by heating it is not needed. The to be soldered area has to be as clean as possible. All oxidised alloy has to be removed by grinding, glass bead blasting or brushing using a clean stainless wire brush.
In this case I used a hard steel round "rose" but in combination with a mill in a Dremel type hand piece.
The whole part is gently heated from the outside with a torch. One can use a propane or acetylene-oxygen torch. Heat the to be soldered area till a soldering rod starts to soften when touching the base metal. The correct temperature is near and when the rod starts to melt when touching the base metal, while playing with the torch flame. When the surrounded base metal starts to "sweat", be careful, do no continue the pre heating.
If the torch is adjustable, try to get a somewhat more blueish flame (reducing flame), means less oxidation. The soldering material when melted will not cover the base natal by itself because of oxidation and surface tension.
With the wire brush or a clean(!) stainless "puddeling" tool, "tin" the area carefully by wetting the surface. If needed, it can be done a few times till all of the area is well tinned (different colour/aspect).
The tinned area can now to be covered with a layer of the soldering alloy which will close the holes. Use the puddeling tool to get a bond with the tinned surface. The solder can be shaped with this tool during a short period and surplus can be removed. Let it cool down slowly.If this is the first time to do this type of soldering try the technique on a scrapped piece of aluminium alloy till you got the feel and confidence to give it a try. Soft soldering is not suitable for stressed connections.
An alternative technique is after having tinned with the aluminium soft soldering rod, fill the area with a normal tin/lead soldering stick (60/40).
If I have to white metal in an all aluminium conrod, I use the old technique of tinning the aluminium with a tin mans tin by using the wire brush technique; a reliable bond between the babbit and the aluminium will be achieved.
You can prevent solder dripping through a hole by covering it from the outside with an exhaust sealing paste. Always use goggles as moist from the air could condensate on the part you are heating and can cause the melted alloy to spit severely.
As I was in the mood, also because of a satisfying result, I continued by restoring the missing rim part of the other water outlet.
Is there something nicer in this world than a good repair........ , on all levels ??"
text & photos by CQ
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