This query comes from Perth in Australia

I am involved in the restoration of a French motor vehicle from 1903 and have run into a major problem in understanding the alloy which is used for major components in the engine which require repair. I would be very grateful if one of your technical people with knowledge in this area could provide some advice.

The car involved is a 1902 French car made by Panhard Levassor and most of the original components are salvageable however the engine has sustained some damage many years ago which requires some welding repairs to the Aluminium alloy crankcase of the engine.

We have obtained by XRF the chemical composition of the alloy which is given below
Al    52.00 
Zn    18.78 
Cu    13.07 
Mg    12.03 
Si    1.56
S    0.55

In today’s world this is indeed a very unusual alloy and we would be very grateful if someone would be able to assist is classifying the alloy which doesn’t fit any of the current standard compositions and if possible to either provide some advice as to a welding procedure required to effect the repairs.

We'd be happy to be referred to anyone who may be able to assist.

Thank You

Jim Runciman

I doubt this is a weldable grade of aluminum. The zinc is going to be a problem because it oxidizes and fumes at a relatively low temperature. 7075 aluminum only contained around 8 to 10% zinc and is considered to be a very bad bet if attempting to weld it with any traditional arc welding process. If 8 to 10% zinc is a problem, higher percentages will probably make it worse.

If there is a chance of success, I would place my money on oxy-acetylene torch welding. The temperature of the base metal can be closely controlled and is considerably lower than that of a welding arc. The zinc would be less likely to fume at the lower temperature. I would try an alloy such as 4043 which has a melting close to that of 1100 aluminum. This is a long shot. Hopefully someone with experience with your particular alloy will jump in on the conversation.

Good luck - Al