What was found
OIL LEAK NOTED BELOW THE OIL COOLER ON A RECENTLY OVERHAULED ENGINE. OIL COOLER WAS PULLED AND GASKETS REPLACED. ENGINE STILL LEAKED OIL. OIL COOLER WAS PULLED AND 3 RECENTLY OVERHAULED COOLERS INSTALLED. ALL LEAKED. INSPECTION OF OIL COOLER MATING SURFACE SHOWED ALL 4 COOLERS TO BE MACHINED CONCAVE TO A DEPTH GREATER THAN THE THICKNESS OF THE GASKET. AN OIL COOLER WAS INSTALLED.