Can someone tell me which hose is the heater inlet hose? Any help would be appreciated. Thanks

 

Which engine / year?

 

4.0L 2003

 

Welcome to CF!

Yes. The hose from the thermostat housing goes into the lower heater pipe. That way air bleeds itself out.

 

Take them both loose, reverse flow with the garden hose until it comes clear from both directions with equal "resistance".

do it again in a week or so.

"rattling" the crud in the core will make it fall out and it needs to be removed. Any of that junk in there will reduce the efficiency of heat transfer.

 

Also, when filling the 4.0, take the temp sensor out and fill it until coolant flows out the sensor hole, put it back in, and finish filling it. Doing this will remove most of the air in the engine.