By passing heater core on a 1988 mustang GT
 

My heater core is leaking and the job is too big for me. Can you by pass the heater core and not cause other issues or damage the water pump? What the best method find an elbow connect or plugged the inlet and outlet heater pipes?

Welcome to the site dude. Guess you're not looking to drive the car in the cold weather or have to deal with a fogged up windshield? I'm no expert, but I guess you could bypass the core, it's just another load on the cooling system, you'd just have to splice in a T so that the coolant could still flow, just go around the heater core, or block it off would work too i guess. Might be more hassle dealing with no heater core than biting the bullet and fixing it though - up to you.

go to canadian tire and pick up a 5/8 hose coupling,, and just disconnect the two hoses at the heater core and loop it