Off-Engine, Water-Air Bubble (Internal And External) Leak Test

Thorough leak testing of the cooler on the bench is performed in two steps, and in both steps, the EGR cooler coolant side is pressurized with compressed air. Step 1 is conducted on a workbench to detect internal leaks (passing of air from the coolant to the gas sections) that would not be visible externally. In Step 2, the cooler is submerged in water to locate external leaks. These leaks often have evidence of dried coolant stains around the leak point.