When priming a pump, which step is essential?

• A. Open bleeder valve
• B. Make the pump as air tight as possible
• C. Decrease engine speed to 700 rpms
• D. Make sure auxiliary cooler is open

Answer: (B)

When priming a pump, the crucial goal is to create a strong vacuum inside the pump so water can be drawn in from the source. If the pump isn’t airtight, air leaks ruin the vacuum and water won’t be drawn up, so the prime can’t be established. Making the pump as air tight as possible ensures a reliable suction that pulls water into the pump. Bleeder valves can help vent any trapped air during the process, but the essential factor is an airtight seal. Changing engine speed to a specific value isn’t universally required for priming, and keeping the auxiliary cooler open doesn’t affect the priming action.