Pressure test and eyes quickly show the source of the leak. 50 year old coolant pressure tester was worthless, no radiator cap, so purchased a plastic cap, drilled an tapped a 1/4" NPT and expoxied in a quick coupler. Followed by a pressure gauge. a regulator with a shut off valve to my air compressor. Hit it with 25 psi, closed the valve, expect the gauge to remain steady.
Really don't have to add a dye to it, Dexcool already has a dye, but I keep my engines clean, if covered with oil and grease, could add a florescent die to it and use a black light. Drips under the right side of the dash show a heater core leak. Wouldn't even think about driving this thing until its repaired, that sweet smelling coolant is deadly causing severe kidney damage.
A long painful death. Learned GM has over 167 heater core vendors, also a high number of water pump vendors in China, some are great, others not so, pump has a 150K warranty, not aware of any for the heater core. Shop labor for the core is about an hour, takes me that long to remember where I left my car keys. Cooling system has to be drained first. My 2012 was already past the 5 year stage because it came out in September of 2011.
New Delco heater core from rockauto.com is 44 bucks, good to get the OE kit, need all that other stuff that comes with it, not just the core if you plan on doing this yourself.
