Most of the time when this is asked it is because the core is leaking. The two negatives I can see is IF the car got hot in the summer you would not have the brief advantage of flowing the coolant through the core. I say brief because in theory it should be cooler than the hot coolant temperature, but shortly after mixing that advantage will be lost. I doubt the actual cooling capacity of the core itself contributes much to engine cooling and remember all that heat would be going into the drivers compartment!  The other negative is dealing with condensation on the interior glass. That would be dependent upon your climate.
 

i had a 55 chevy built for sale in the south that did not come with a heater .. your car will not know the difference ..

The consensus is that overheating shouldn't be an issue if you eliminate the heater core, provided all your cooling system components are up to snuff.  If they weren't you would have overheating issues with or without the heater core.  If you decide to go with an electric fan, you may find that your current alternator may not be up to the task and may need to upgrade to a higher amperage unit.  It may bring a quicker death to a marginal alternator.  It is a good upgrade that won't hurt anything if you get the right kit, install it properly, and have a stout enough alternator. 

My opinion:  install a new heater core.  While it isn't a "fun" job, it's a snap compared to modern vehicles, and you can get one from Rock Auto inexpensively.  Sometimes in the Spring or Fall when using the defroster, you will appreciate having a little warmer air to keep the windshield clear.  Not to mention, if you have a wife or GF, they tend to get cold even when we are sweating...

My $.02...

If you have a new one I wouldn't even bother testing the old one.  You should never have to mess with this again once the new one is installed.

Where are you in PA?  I used to line in Middleburg.  Near Selinsgrove, Sunbury, Lewisburg, Mifflinburg.

I'm in the southeastern part. Just south of Allentown.


I'm not sure as to what I may do here. I do have it all apart now, just wanting to get it all back together. Hunting season is starting soon and I won't have time after that. I may end up just bypassing for now until spring. Just need to have something to be able to run it though out the winter. As I said earlier, I don't drive it in the winter months. Driving season for me is over anyway, starting to get cool now.


I'll keep up to date as to what I do (sitting on the fence). I do appreciate all the feedback. Thanks!

update: I went the route of just putting in the new core. All back together and doing fine.