1998 Dodge Dakota

V6 model.

Odo is just shy of 100k. We're planning a party.

When I crank the heat for the morning commute, I'll get heat for a little while--say, 20 minutes--when my temp gauge will ramp up to near the redzone over a couple minutes. At that point, I lose heat (air still blows, but it's cool). When I turn my heater off, the gauge settles back to normal operating temp.

I haven't noticed any fluid leaks inside the cabin, so I don't think the heater core itself is leaking. I have noticed some external leaking, but previously figured it to be condensate--tomorrow if I notice any puddles I'm going to give it a whiff.

Any ideas on what to check? Could it be a partial blockage within the heater core? Or could it be my thermostat needs replacing?

If I do end up needing to replace the heater core, am I going to need to discharge the AC system in this make/model?

Thanks in advance!
November 19, 2007.

You should start by checking the coolant
Before 1st start in the morning pop open the radiator and check the antifreeze
Top off if needed and then start let it idle for a 3 or 4 min and check again top off if needed
As for thermostat it s always a plus to change and aging thermostat
Coolant flush will be ok with that thermostat
Good luck

Nov 19, 2007.
Just replaced mine - same truck. Loads of fun. But if it's not spilling coolant on your floor the core is at least intact. Sounds to me like your thermostat has gone bad.

Nov 27, 2007.
I know the heater core needs replaced. What I dont know is how to get to it.

Linda richards
Nov 27, 2007.