Connect a low-pressure air hose to a fixture on one of the flanges. Immerse the block into a tank of water heated to the engine s normal operating temperature. Allow the engine to soak for approximately 20 to 40 minutes, as specified by the manufacturer. This allows the block to warm to the temperature of the water. Apply approximately 40 psi of pressure to the block and watch for bubbles.
Bubbles indicate a crack or leak in the block.
Determine what repair is needed or can be made when you identify the source of the bubbles. If you cannot dip the block, you may still perform the air pressure test. Attach the hose to a fixture secured to an opening to the water jacket. Pressurize the water jacket. Carefully spray soapy water over the block and look for air bubbles caused by the pressurized air.