Ok whats everyones take on this problem. Buddy of mine has an 03 Ford Ranger 4.0 4x4, has ice cold heat.
He replaced the T Stat and the heat does not work. So he takes it to someplace called docs automotive and dude tells him the heater core is plugged, quoted him around 1500 to do it. You have to pull the dash and heater box. I look at it and at first glance the one hose going into the box is kind of cold and the other is fairly warm/hot so I look at the heater control valve and it is open so I agree heater core it shit
I replace the heat core, vacuum fill the radiator and make sure the coolant is full. Drive the truck and no heat. Check the lines to the core and on is still 70-80* and other is maybe 125*. No heat, look online and I guess some trucks have problems with waterpump impellar rotting so we go ahead and replace it with no fix....
Temp gauge stays in middle while driving....just no heat. lower radiator hose stays fairly cold and upper gets to maybe 145-150
suggestions of thoughts.