The major methods include: Fluorescent Leak Detection Employs an ultraviolet or UV/blue light inspection lamp and fluorescent dyes to find even the smallest leaks quickly and easily. It locates multiple leaks and those not found by any other method. Its lack of disadvantages explains why it is the most popular leak detection technique. In addition to diagnostics, it is the only preventive/programmed maintenance method that detects all refrigerant and fluid leaks. Visual Inspection This labor-intensive procedure is very time-consuming except for the largest, most obvious leaks. Some people lay newspaper down to try to locate the general area of the leak. They will check the color of the fluid to try to identify what system it is coming from, i.e., red for transmission fluid, green for coolant, etc. However, it’s often difficult to pinpoint the exact source. Cannot be used for refrigerant leaks or for small leaks which evaporate right away. It’s difficult to detect clear liquids. Soapy Water and Bubble Solutions Although it’s inexpensive, this method has a number of serious drawbacks. In addition to being very time-consuming, it is not applicable to oil, hydraulics, transmissions and fuel. Only for refrigerant leaks. Talcum Powder Spraying foot powder on and around a suspect area may help you to find the leak if you’re lucky. But don’t run the engine, or you’ll make a real mess. This powder can also foul up carburetors. Only for oil leaks. Ion Detector (“Sniffer”) Detects only the general area of a refrigerant leak, not the exact location.This fragile device does not withstand hard use. In addition, it does not operate well in humid conditions. Only for refrigerant leaks. Compressed Air Used in water-cooling systems, it can damage hoses, radiators, and other components. It can actually cause additional leaks and enlarge existing ones. Only for coolant leaks.