2010 Dodge Journey SXT with the 3rd row heating stuff

specs: 2010 Journey SXT with the V6 and AWD. Has the rear HVAC setup.

Driving to work on Monday the Journey suddenly overheated. Pulled off the road within seconds and noted a lot of steam and dripping. Was towed back to our work area (I do side work on our own family cars as a hobby) Used a pressure tester the next day and discovered the rear “T” for the heater core to rear HVAC was leaking. It has no visible cracks-but under pressure it was hissing and spiting coolant.

Obtained a repair kit and installed it yesterday. (Also replaced the upper radiator hose, as it was getting weak) Refilled the system with the correct 50/50 mixture. Noted it only took a gallon. (figured it should be more considering how much it left on the highway). Started it up and did the usual purge procedure.

The ol’ girl did send some air bubbles up and out. The temp on the gauge was dead center. So I stopped when it hit the normal operating mark. (I did feel the upper hose getting warm) Added a bit more coolant so the level was correct. Then I noticed zero heat in the Journey. Both front and rear units blowing ice cold air. Figured it probably had a large air pocket, so I drove it a short distance so the nose of the ol’ girl was pointed upwards more. (My family lives on a hilly road) Still no heat. I then noticed the temp gauge was starting to creep up to the 3/4 mark and about to trigger the overheat warning. Parked it and shut it down.

The entire system then started to act like one of the old school coffee pots (and pretty violent with the steam blowing into the overflow jug.) I then reached my hand to the rear heat pipes- Stone cold. Same for the front heat pipes. The upper radiator hose was extremely hot, as well the lower hose at the “t” junction where it puts the overflow hose into the lower radiator hose. So one would think it has circulation. But judging my how much steam pressure that was being generated- I have a feeling that’s what I was feeling at the hoses.

Part of me thinks it’s air locked and didn’t purge correctly. The other part of me is thinking the part that failed was just a symptom and the water pump failed. (pump fails=rapid increase in pressure while at highway speeds=boom)

Would there be any quick and dirty methods to check for a potential bad water pump? I’m thinking pulling the heater hose under the intake and pointing it into a bucket. If the water pump is functional- It should purge any air in the block and spew out. (Thought process: Water pump will always circulate to the heater core during engine warm up. If the system is air locked to the heater cores, a wide open path at the source should pump freely.)

Thought it might be a stuck thermostat, but that should still allow coolant to circulate to the heater cores. If it turns out to be a dead water pump- I’ll probably do a trifecta (timing belt, water pump, and thermostat at the same time)

Any ideas are welcome as mentioned. This is our daily driver, and I’m using the wife’s “summer fun car” for the next few days.

S-