I would like some direction or opinions. 2008 Dodge Grand Caravan 4.0 liter 195,000 miles. This summer there seemed to be a head gasket problem (some steam from the exhaust and running warmer than normal). I went for the Blue Devil repair. I followed all directions and it seemed to work. Problem resolved. That was 5000 miles ago. Now that its cold I have no heat. I have the rear heater core out of the system and have the front heater core routed from the engine back to the engine. The blend door motors are removed so i can control the flaps by hand. The inlet hose to the heater core is hot but the return hose is not. I tempoary installed a clear plastic hose to monitor the flow to the heater core and the water was moving but couldnt let it get up to operating temp with the cheap plastic hose. I put a new heater core in. Same complaint. I have vacuum bled the system multiple times. I installed an auxillary coolant from another car in the return heater hose . No help. The van will get a little heat until you start driving it then it starts blowing cold again, New thermostat 2 times , Tempature gauge runs dead in the middle. If I let the van cool down and start it back up it will start getting heat until you start driving it or rev the engine. I suspect there is a problem with that head gasket or head gasket blue devil repair that i introduced into the system. Does anybody have any other ideas before I pull the heads off of this thing Thanks

 

I think Ill try a radiator before i pull the heads

 

why would it be the HEADs ???? ......if you have hot coolant in the pipes and the van is not overheating - the coolant is flowing correctly trough the engine .....heads are OK . i you have a heating problem ...may be a radiator core that is blocked , if not , water pump maybe damaged and not making enough circulation .....but you would notice probably some overheating of engine ,, or running hotter than usual .....or air in the system ? ...- Use one of these HIgh Funnels that attach to radiator and are above the heater core level ...so air comes out....

 

I would leave the had gasket alone. If there's a problem with the head gasket, you'll see brown residue in the oil cap or the tip of the oil dipstick, or smell sweet coolant in the exhaust, or your tail pipe exhaust will be white(r), though this can be decieving.

You didn't mention if you did any work with the water pump. If it's failing (or gone), it won't move the coolant.

You said the heater core inlet hose was hot, but not the return hose, but you also changed the heater core? I would have thought there's a blockage in the heater core, but if you put a new one in....

I would change the thermostat, and radiator cap. Then use the special coolant filler funnel (they're pretty cheap and indispensable when refilling coolant).

Of course this is assuming you're using a 50/50 coolant mix, and not much higher.

Good luck.