Thank guys for all the advice. I will drill a 1mm hole at the top of the crack to stop this progressing and then clean and grind out the crack area and apply some sort of aluminium repair material to the crack. I am in South Africa so am not familiar with JB Weld. What should be inserted into the newly drilled hole. As this area is not under pressure could I insert a bit of aluminium epoxy putty.

 

yes, the idea of the hole is it will keep the crack from continueing to spread but you will want to fill the hole with whatever you use on the crack and file it smooth.

 

MLX665 GP,
JB Weld is similar to some of the Pratley products, eg you could use Pratley Steel.