Chasing an intermittent leak by eye wastes hours and usually ends with a guess. This Mastercool kit takes the guesswork out of it: add the fluorescent dye to the system, run it a few minutes, then sweep the UV light over the area and the leak glows exactly where the fluid is escaping. It works across the fluids you actually deal with on a transmission and engine job, including automatic transmission fluid, engine oil, power steering fluid, fuel, coolant and A/C refrigerant.
The light is the reason to buy this kit over the cheap battery flashlights. It is a 12V, 50-watt high-intensity inspection light that clips straight to the vehicle battery, so it never dims partway through a job and there are no batteries to kill. The long cord lets you reach under and around the engine and up over the bellhousing area where transmission and cooler-line leaks like to hide.
The kit is built to actually diagnose, not just light things up. It ships with a cartridge-type dye injector fitted with an R134a coupler and an R12 adapter, a 1 oz cartridge of universal oil/ATF/fuel fluorescent dye good for about 10 applications, a separate 1 oz engine coolant dye, a 4 oz bottle of dye remover for cleanup, UV-enhancing safety glasses, and 25 service labels so you can note what was dyed and when. Everything stores in a molded carry case for the truck or the bench.
A few notes from the field: always wear the glasses and gloves when injecting dye, purge air from the injector hose before first use, and clean the suspect area before dyeing so a fresh leak stands out from old residue. Ships from the USA.
