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Coolant Leak

1.5K views 2 replies 2 participants last post by  Maddog1963  
#1 ·
So I have a 2003 envoy xl with a coolant leak inside on the passenger side floor, and it also seems to leak behind the rear tires after driving for a while. I pulled out the heater core and replaced it thinking that was the likely suspect, but the leak continues. I am stumped because there is no leak under the engine bay or anywhere outside the fire wall that I can see. Any thoughts would be appreciated.
 
#2 ·
Plugged evaporator drain?

I have a Monte Carlo that had a plugged evaporator drain. The heater box filled with condensation and perhaps rain; I could hear the fan hitting water especially on left turns, and then it'd throw fog or mist out of the dash vents. Had some water on the carpet that didn't stink like antifreeze.

Pulled the drain nipple off the firewall, and got about two quarts of water out of it. That was the end of noisy fan and fog from the dash...but the blower-motor resistor unit had corroded. I had to replace that before the system functioned properly.
 
#3 ·
Ended up being the rear heater core. I was confused because the carpet in the back was completely dry on top and only started soaking up on the front passenger carpet.
The only difficulty now is the connectors on the rear heater core and the hose are rusted together around the threaded screw. Bypassing it for now, hoping to find a fix later on.