coolant on floor with heater turned off

gb429

New Member
Oct 15, 2020
2
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1
Australia
Hi well i know its not mustang but its a 68 cougar (same same) driving home and temp goes up almost instantly. Heater was turned OFF and had coolant on floor under heater box.
Pulled over and cooled it down, topped it up , drove it home with heater ON. Ran perfect temp no leak.
dont think it can be the core as heater was off and it would have leaked more with the heater on??????
Also there is like a drain hose just hanging out of the firewall under heater hoses, any idea what this is for???

Any help or ideas appreciated. In Australia so not a great deal of info here.....
 
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The hose hanging out of the firewall is your A/C evaporator core drain hose. Water from condensation drips from it when the A/C runs.

Coolant in the floorboard is either coming from the heater core or a heater hose. It leaking more with the heater off could be due to it having a lower temperature (and thereby lower pressure) when the blower motor is pushing air through it.
 
The hose hanging out of the firewall is your A/C evaporator core drain hose. Water from condensation drips from it when the A/C runs.

Coolant in the floorboard is either coming from the heater core or a heater hose. It leaking more with the heater off could be due to it having a lower temperature (and thereby lower pressure) when the blower motor is pushing air through it.
cheers that what I thought the hose was.
The heater was off and had been off for a few weeks, it just dumped the coolant staright away as if it blew something. I just ran it again and there is no coolant coming from anywhere with or without the heater on. let it get up to 200 f as well to check but not a drop.....

Its a mystery???????????
 
running the heater doesn't stop coolant flow to the heater core, it only stops (or rather slows) the flow of air across the heater core. It sounds like the leak occurs when the cooling system reaches a high pressure, such as when the thermostat opens or you're climbing a steep hill.
 
Its either those hoses or the core leaking under pressure as others have said...happily, replacing a core is not a huge task in these cars like it is in new ones, should only take a couple of hours to drop the box and change it out.