Still no luck. vice grips on the heater core hose with the flow control valve on it and still have coolant loss. i can usually smell it near the end of a trip when the engine is rather hot. im running out of ideas about where this leak may be. it would seem to be a leak which must be evaporating when it hits the engine.

 

In order to stop any fluid "pressure" from reaching the core, both hose's need to be pinched off.

 

All signs point to the heater core. This thread can be marked solved. Thanks everyone fir the inputs.

 

Because of the nature of the removal/replacement of the heater core is a ton of work, I would just disconnect the hoses and bypass the core by sleeving them together ...Use good clamps !! I would also drain the oil and measure the volume to verify that it doesn't contain antifreeze. Over 4 1/2 qts, you have a blown headgasket.