The quick-connect fittings for the heater hoses tend to leak engine coolant. This problem commonly occurs because the metal housing has become brittle, which can break and cause leaks.Google+
Car Problem Reports
Chevrolet Tahoe Quick-Connect Fittings For Heater Hoses May Leak Engine Coolant
Chevrolet Tahoe Problem
Average Mileage: 146,558 mi (45,971 mi - 199,000 mi)
Visitor, 1996 Chevrolet Tahoe, 176,382 mi
leaking from quick connection on heater core inside under the glove box. Replacement heater core was $35.00 at local parts store. Was quoted $800.00 to install at dealership. Did repair myself in 5 hours for free. its a bad design and could be done in a half hour if they would put an access door in engine bay.
Visitor, 2005 Chevrolet Tahoe, 115,000 mi
Filled my coolant up week ago and now it's almost empty.
Visitor, 1999 Chevrolet Tahoe, 45,971 mi
this appears to be my identical issue.
leaky quick connects may leak fluid