Before you perform the air pressure test, make sure you completely strip and clean the block. Then, follow these basic procedures:

1. Seal all of the blocks freshwater passages with gaskets and flanges.

2. Connect a low-pressure air hose to a fixture on one of the flanges.

3. Immerse the block into a tank of water heated to the engines 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.

4. 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.

Water Pressure Test

The water pressure test is similar to the air pressure test, except that defects are indicated by water leaks rather than by air leaks. Before you perform the water pressure test, strip and clean the block Then, follow these procedures:

1. Seal off all but one of the freshwater openings with flanges and gaskets. Make seals airtight.

2. Fill the water jacket with fresh water until all air is purged from the water jacket. Seal the fill opening with a flange that contains an air hose coupling.

3. Attach an air hose and pressurize the water jacket to approximately 40 psi (see the manufacturers manual). Maintain the pressure in the water jacket for at least 2 hours.

4. Inspect the cylinder bores, air box, oil passages, crankcase, and cylinder block exterior for the presence of water. The presence of water at any of these locations indicates that the water jacket has one or more defects.