Method of eliminating porosity defects within aluminum cylinder blocks having cast-in-place metallurgically bonded cylinder liners

A method of eliminating shrinkage defects within aluminum cylinder block castings having metallurgically bonded cast-in-cast place cylinder liners, said method comprising the steps of;

• forming a metal cylinder liner (12);
• metallurgically bonding a zinc-based metal coating material (14) to the liner (12) forming an alloyed layer of coating and liner metal adjacent the liner and an outer layer of essentially pure zinc coating material;
• depositing the coated liner (12) within a cavity (18) of a cylinder block casting mold (20);
• casting molten aluminum cylinder block metal (22) into the cavity (18) and around the coated liner (12) causing the coating (14) to melt and further alloy with the cylinder block metal (22) and allowing the cylinder block metal (22) to solidify and metallurgically bond with the liner (12);
• and removing a sufficient amount of the outer coating layer prior to casting which would otherwise melt during casting and infiltrate the cylinder block metal (22) forming undesirable shrinkage defects within the resultant block (22) upon solidification while maintaining a remaining portion of such outer layer material intact to provide corrosion protection to the liner prior to casting.