Good thing I haven’t finished installing my pressure gauge yet.  Might have another job for it.  My heater core might be leaking in wives 06 CRV.   I get a wiff of anti freeze when  temp gauge starts to move.  I’m thinking that T-stat is also opening about the same time.  I don’t see any wet floor or any wetness on hose clamps, but do smell it. 

Trying to confirm if I have leak or not.   I think a valid test would be to plug off heater core and put about 5 psi into heater core and if no leaks, pressure should not leak out. 

Do you think that is valid test?  Any other test I could do?

Thanks

You shouldn't have to isolate it if the rest of the system is for sure good. You can just pressurize everything and be good. If you want to be absolutely 100% positive the heater core is good, I think your method is best. 

I would pressure test the entire system cold. Then if you pump up to normal pressure and let it staand the coolant will leave a tell tale sign of where its leaking. If the heater core is leaking typically it will drip from the A/C drain if it's not plugged up.