Which diagnostic technique is recommended to locate a coolant leak source?

• A. Replace entire cooling system
• B. Pressure test, dye or UV leak detection
• C. Ignore small drips
• D. Check only the temperature gauge

Answer: (B)

Locating a coolant leak source is best done by actively testing the system rather than waiting for symptoms to appear. Pressure testing the cooling system pressurizes it to its normal operating range, which makes leaks that only show up under pressure become visible. If a leak isn’t obvious by sight, adding a tracer dye to the coolant and using UV light lets you see exactly where the dye escapes, pinpointing the leak without disassembling components.

This approach is practical because coolant leaks can be small or hidden, and relying on a temperature gauge or waiting for drips can miss the problem or lead to overheating later. Replacing the whole cooling system or ignoring small drips isn’t appropriate; both waste time and risk further damage. The two-step method—pressurize to find leaks, then use dye/UV to locate the source—provides a precise, safe way to identify and address the leak.