Maybe a stupid question but looking at firewall in a 94 ranger. Which heater hose is the inlet and which is the outlet...looking at firewal from front of truck? I just replaced my heater core 3 months ago and all was fine, but yesterday blew again. I wonder if I hooked up hoses wrong or what? Help!

 

Welcome to the forum


Heater cores don't have an IN or OUT, and the hoses SHOULD BE reverse every few years to keep them clean of debris, larger bits can come in then can't get out of smaller passages, reversing the hoses pushes the larger stuff out the way it came in.

If new heater core is leaking then it was bad from the factory or it is one of the hoses that is leaking and spraying coolant inside hole in firewall.

Radiator cap is rated at 14-16psi, these can fail to open at 16psi which will cause higher pressure in the system, but it is 99% more likely that a hose would fail not radiator or heater core if pressure got to high.