I am working on the top cowl panel of a ’69 Mustang Mach 1. Water got in under the sealant at the bottom of the windshield and ate right through both cowl panels. I cut out and replaced the rusted metal with a patch made of cold rolled 20-gauge sheet metal. I thoroughly cleaned the weld zone and secured the patch in place using Eastwood’s panel clamps for butt welding. Using a 110-volt Lincoln SP135 Plus I welded the patch into the cowl OK – good penetration, then ground the weld bead with a dremel tool to blend with the surface. Now I see very tiny hairline cracks here and there right in the middle of the weld bead. Some areas are OK – good solid weld, others have these little cracks. Tried re-welding and re-grinding, same problem. Stress cracks from cooling? Does someone have any recommendations to solve the problem.
Thanks and much appreciated.