Chrysler Repair: no heat: 98 Dodge truck, dodge ram 1500, coolant level

Question
Hello,

1998 Dodge Ram 1500 4 speed 5.2L/318ci 193K. Dad's truck.

Water pump was leaking so I replaced that, refilled the system and burped accordingly. No heat. Replaced thermostat, refilled system and ran to burp accordingly. No heat. It runs about 195 or so right about for the thermostat. I don't see any leaks. Had it run for 1/2 hour and no heat. Selector knob is working. It was mentioned to me that there was a little bit of coolant drippage from the heater core drainage hose down below over the Summer. It has been below zero for weeks here so I can't use the hose to reverse flush the core and I have no garage, work outside. My question is this. If the core is leaking, would I still get heat? If the core is plugged, how do I determine this and verify it before taking the next step. I guess a last question would be, do you have any tricks of the trade for remedying either one of these scenarios without taking out the core?

Thanks very much.

Answer
Hi Mike,
I don't have any manuals or experience with the truck line but you might observe the temperature of the two hoses for the heater where they come out of the firewall. If they are equally warm (approximately) that is a sign of good flow, if the return is colder than the input hose then that is a sign of either clogged core, or it could be air trapped in the core which can only be removed by dropping the coolant level below that of the core, refilling, and burping. Be sure the temp setting is full hot at the controls with the engine running when you turn it off to do such a drain/refill. Also, I don't know if your coolant hose system to the heater might have a heater core by-pass valve in the engine compartment (which is used to shut off that pathway when the AC is running, as was the case in the 80's and early 90's, so look for any such by pass between the two heater hoses that might be short circuiting the flow to the heater core.
You might check with Kevin to see what he can suggest.
Roland