Hello everyone, My names is Jamie. I am new here and new to a dodge also.I just recently purchased a 1999 Dakota Sport, that had some neglect but was in good shape for the most part. My dad is helping me with getting things back to normal on this truck,but now he is stuck on the heat issue. We flushed the entire cooling system(even the heater core),new thermostat,new water pump,hoses, everything. Still no heat! He fixed all the hoses and things under the dash, you can here the little door closing when you switch from hot to cold and everything.The coolant is circulating good and there is flow through the heater core, but its not warm in the truck. Does anyone have any ideas i can tell my dad to try? I would be greatful for any help.

Thanks JDW

 

Hi Jdw,

Welcome to the forums.

Is the engine showing "warm" on the gauge?

How are you determining the flow through the heater core? A very common problem is that the heater core clogs. Even a partial restriction will limit the amount of heat.

Disconnect the hoses from the heater core and flush it by itself, out of the system. You'll likely see a lot of crud come out. Using some short pieces of hose, pour some cooling system flush into the core and let it sit for a bit, then flush it out again, repeat until clean.

 

Yes we flushed the heater core seperately until it was clear. My thermostat is a 195 degree and that's about where my gauge goes to, maybe just a little more. As far as the flow through the core, while it was running at normal temp, dad popped off the return hose. Sure enough, very hot water.

Thanks jdw

 

Also I noticed while driving today... if I am traveling at low rpm's , it starts running a little hot. When I mash the gas and get the rpm's up it cools down to normal. Still no heat what so ever. We checked the coolant and it is full.

 

A little rise in temp after prolonged idling or low speeds is normal. Check the operation of your clutch fan and make sure you've bled the system.

About the heat, this is from the factory service manual:

OBSTRUCTED COOLANT FLOW
Possible locations or causes of obstructed coolant flow:
* Pinched or kinked heater hoses.
* Improper heater hose routing.
* Plugged heater hoses or supply and return ports at the cooling system connections.
* A plugged heater core.
If proper coolant flow through the cooling system is verified, and heater outlet air temperature is still low, a mechanical problem may exist.

MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat:
* An obstructed cowl air intake.
* Obstructed heater system outlets.
* A blend-air door not functioning properly.

TEMPERATURE CONTROL
If the heater outlet air temperature cannot be adjusted with the temperature control **** on the heater-A/C control panel, the following could require service:
* The heater-A/C control.
* The temperature control cable (not connected, not routed, or not adjusted properly).
* The blend-air door.
* Improper engine coolant temperature

 

Where you able to figure out the problem JDW? I am having a very similar issue except my 3.9 runs cold, as in in winter temps cruising downhill it will drop down to the 135 range. When I am running it hard it will not get over 160 ish. Just got done with a 1,000 mile road trip in through the rockies with almost not heat. It was cold.

 

No we have not got it fixed yet but still trying. My dad has a friend that told him to try flushing the whole system a couple more times and try a different thermostat. Also might try changing the coolant sensor, right now he said he woukd try just about anything.

 

The coolant sensor will not affect the engine temp. It's just a sensor.

Bad thermostat, that could make it not warm up. Since you say the temp gauge is rising, that seems a bit unlikely. You definitely want a 195 in there for heat.

A partially clogged heater core is the most likely problem. If you aren't flowing a LOT of water, it won't ever get hot. Again, this is very common in Dakota's.

 

I had same problem with my 98 3.9 , i fixed by changing heater core, rad cap, t stat, water pump. check all hoses. The heater core is a b**** to do took me 12 hrs. well worth the time though.

 

Just jumpin in ....

When i bought this pick-up, the guy who had it, did install a '' cardboard '' in front of the engine rad...( YEAHHH ) which i removed of course.

I replaced the thermostat, the temp sensor and the metal pipe comming out of the water pump, (sooooo rusty ).

Now, it remains at 195 no matter what even in canada ( last week it was -30 celcius) BUT the heat generated by the inside core is marginal, it will need a good flush OR a new core.....

I've noticed though that the air flow is much lower when it's on hot compared to cold position.
Thanks for the tip on this one, i paid more attention this morning and i noticed it....MUCHHHH lower air flow on HOT position compared to COLD position.
May be some leafs clogging, restricting the airflow to the heater rad....will kee p you posted on this one.

Cheers