i have replaced a heater core in my corsica about 9 months ago. the heater core has a plastic liner/tub hannging underneath it which collects moisture-leaks and does have a small elbow which passes thru the firewall to dump the water onto the ground. If you are leaking thru that elbow quite a lot chances are your core is bad. The oem core was a dim witted design it has two plastic tubes press fit onto the aluminum core in my case the core was fine but the plastic tube cracked in half causing a leak.

Answered by car tom
23 questions asked