Re: 05 wk coolant leak after replace heater core.
Did they replace the heatercore and aluminum lines that come out of the core? sometimes those aluminum lines are known for having pin holes you cant see . I would take it back and have your mechanic look at it , if you trust him . When i did my heatercore i replaced the Core, aluminum lines that go into the heatercore , and o rings . From what you discribe Im guessing its either a faulty core or o-rings are shot.
2005 jeep grand cherokee limited 5.7 , AFE Intake, Dual Exhaust , SRT8 Front bumper.
1999 Turbo Mustang Cobra..Too much to list