Zachtheame

Well I replaced the heater core and lines so that’s already been eliminated and there is good flow coming from the return of the heater core so I am starting to suspect the issue is on the return side

Any chance you have a photo of the extra fitting? I don’t see any but I don’t know where to look

We sure did, the fitting snapped when we tried removing it necessitating it’s replacement. It sure is a head scratcher, we’ve tried everything. And it’s something that happened between this year and last year because the heat was stellar last year

We replaced the inlet and return lines completely except for the metal tube section in the middle which we cleared with a wire bottle brush. If there is an obstruction it would have to be within the water pump itself but I pulled the outlet line off and ran it and the flow seemed as free as I would expect it The supply line originated in the block and terminated at the water pump

One line is 122° and other line is 95° I have confirmed the blend door is moving the truck has A/C but it was added after the fact by the dealership

Hello everyone I’m new to this forum so I hope this is an acceptable topic. I have a 1996 K1500 4.3L and I’m having heating issues. Started off with no heat and ended up needing a thermostat. That worked for a winter and now we’re back again. I determined the heater core was not allowing fluid through so I put a new core and hoses in and confirmed fluid is flowing as well as another 195° thermostat just for good measure but the truck still has questionable heat. Where should a guy look next? It runs pretty consistently at 170°F despite the 195° thermostat.