[iexcelr8]

I have a '68 390 with A/C. On occasion, coolant will spew out of what I think is just the drain hose for the A/C (the one that comes out of the firewall just under the heater core outlets). Is this normal? Have I just overfilled the coolant system and this is where it is coming out? I suspect not, but I'm obviously confused. If it matters, the heater bypass valve is not functioning (I don't get any heat in winter unless I bypass the bypass). Is this part of the problem?

Any insight is appreciated.

 

[James67]

Just a guess, but it sounds like a bad heater core. Heater bypass may be working intermittenly, allowing the coolant to flow thru the heater core.

 

[Lemondrop]

Heater Core for sure . I dunno how they route on this , the hose connections most times are under the hood but if they for some reason are inside the airbox the clamps could be loose . I imagine the clamps are outside on the firewall ....
I'd say your heater core is leaking . You could pypass it by connecting your heater hoses together until you can remove the box to replace the core .