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1966 heater core failure

Started by Rob Leonard, September 08, 2008, 01:00:49 AM

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Rob Leonard

Where will the coolant leak when the heater core fails on a '66 equipped with climate control (under the car or into the passenger compartmemt)? If I shut off the climate control system will the heater control valve make the leaking stop?

I believe that I just lost mine heater core - There is coolant leaking under the car and it isn't coming from any of the usual suspects - hoses, radiator, water pump,...

Thanks, Rob

"Cadillac Kid" Greg Surfas 15364

Rob,
The most frequently reported symptoms of a heater core failure would be "fog" coming out of the AC vents.  Your heater core is located on the engine side of the firewall, so leaks are most likely to show up on the outside of the passenger compartment, but they could be carried over during fan operation.  No, just tuning off one side of the heater water circuit by the heater flow control valve will not stop a leak, because the other side of the hater water circuit still is connected to the car's cooling system. Disconnecting the hoses and pluging the ends will stop a leak in the heater core, and it will also allow you to test the heater core.  with one side of the copper heater core, where they extend through the heater case on the firewall plugged, you can pressurize the heater core with a cooling system pressure tester and adapters.  If the system holds 10 pounds of pressure it is okay.  If it leaks down, the next step is a heater core replacement.  I might add that a small leak, not like the one you describe, usually starts when the cooling system warms up.  That is when you would get the "fog" out of the AC system vents.
Check it out
Greg
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Jim Govoni CLC 20546

1953 Series 62 
1966 Fleetwood 
1969 deVille Convert.
1941 Series 63

Rob Leonard

Greg - Thanks for your insights. Rob