I've a 2010 Cobalt LT, 98k miles. First off, is there a way to bypass the heater core so coolant stops leaking into cabin? If so, how please? Next, could the issue be leaky coolant hoses (leading to heater core) or coolant pump? I recently switched from parking in garage to parking on our steep driveway and I wonder if the coolant pooled/pressurized and created air pockets or something? Is it easy to check for leaky hoses or the pump yourself? (Do you have to take apart dash for that?) Finally, is heater core replacement doable yourself? Does the a/c freon need to be recharged or some such (requiring special tools)? Thank you! ---------- Post added at 11:44 AM ---------- Previous post was at 11:12 AM ---------- I'm also worried about electrolysis. My husband did a coolant flush in July. As well he replaced knock sensor and actuator camshaft sensors. Anyone had experience from heater core failure due to electrolysis? Is there something I should look for or can we test it easily ourselves?