Hello everybody I have a 2000 Dodge Dakota with a 3.9 L with four-wheel-drive and automatic transmission, I am running into a problem where is the truck when idling to get up to operating temperature but the heater blows barely lukewarm air. However, when I press on the accelerator and the rpm's up to between 1500 and 2000 rpm's I start feeling the heat, this is also when I have the heat setting set all the way up and with the blower on high. I have been keeping up on the fluid levels and also I have back flushed the heater core, but it seems not to have changed. I've already had the water pump replaced, also I have had the thermostat, and my system has been completely flushed. Also on a side note both of my hose lines for the heater core are hot the in-line has to the core is hot and the outline to the core is slightly cooler but still has heat to it. Now I do have a couple questions:

1. If I do have an air pocket in the system how would I go about burping the system? Since this is a 3.9 L engine the radiator Is on the return hose line from the engine block to the radiator. So my radiator cap is not even on the radiator. And I do have a service manuals that the mechanics use for this particular year and it says that I should open a plug on either side of the engine, but I'm not sure if I have them.

2. If this ends up not being in their pocket situation what else could be the problem? I know I've read that a few people have suggested making sure the thermostat is working properly but how can you test if it's working properly? Also how does the thermostat be a problem with heating if there is a separate line that goes from the engine block to the core and the thermostat controls the flow from the engine block to the return line hose back into the radiator?

If anyone can help me with this would be greatly appreciated

thanks

 

Your truck's heater core is partially clogged. Very, very common on our trucks.

Do a Search here. The forum is loaded with info on what to do.

#1) Do a complete flush/reverse flush of the heater core.
#2) Replace the Thermostat and TEST the new one before reinstalling it.

 

if you read my post i have already done all of that and still has the problem. i have flushed this x3 already between this year and last year.

 

Could you perhaps give some detail on the flush process you used? It would help us all to learn more about what you did and see if anyone has further suggestions. Did you use a flush kit? What sort of pressure? Did you let the flush fluid sit in place in the heater core and for how long?

Not trying to be critical here...it would just help others to understand how you did it.

 

My truck had that same issue as yours. I did the same as you flushed the hell out of it. Still poor flow and not that great of heat.

The concensus on my truck from most here was the heater core is STILL somewhat clogged. Most likely due to an anti-leak Additive used by a previous owner. I was warned if I kept trying UN-clog it, it perhaps would bust the covered up leak wide open once again.

Alternatives ?

1) Rip out the whole dash and replace the heater core myself,
2) Pay someone else $500-800 to do the job.
OR
3) (what I will do...if needed) Buy a 1200 Watt Inverter, buy a 120v 1000 Watt plug in ceramic heater and call it a day.

That's on my truck. Your's is "perhaps" in the same situation.

Perhaps not ?

 

I had the same "cold air-rev up and get warm air" problem,I just back-flushed the heater core yesterday and solved the problem in 20 minutes..When looking on you-tube I noticed one post where they were using a citrus base compound to soak in the heater core ,, perhaps there is something to use to dissolve whatever is clogging the core ,, other than that you will have to change the heater core.. I tried cooling system sealers and found it's cheaper in the long run to fix the problem right the first time,,, (unless your passing it to someone else) Good Luck

 

Anything acid based can proabbly break crap apart with time. Citrus is an acid, so yea. Soda is too- you'd be surprised what some soda will do to certain things.

 

You know, you're right. I've always heard It said that Coke will dissolve just about anything. Maybe one of you guys can try filling a clogged heater core with coke, plug it temporarily, let it sit for a few hrs, then flush it out with water.

 

Any soda will dissolve battery corrosion in a pinch. Sometimes it is all you need to get a battery connection restored well enough to start the car.

 

sorry guys i been busy with work and such. I did back flush the heater core with a garden hose and water. The first time i did this i used radiator flush but might have not waited long enough for the flush to work and i might have not flushed both lines out properly. Also i had a friend of mine do the "Squeeze Test" on the return line where the thermostat sits from the engine block and it was very firm. so my plan is to take the A/C off and the alternator along with the bracket and test the thermostat also i found out i also have a leak dripping off of the back of the transmission casing so i seen other post about it and im hoping it just the bypass tubing gone bad or never went back on right when the water pump was changed.

Also does anyone know how to purge the system of air off of a 3.9 L since the radiator cap is on the return line?

Does the 3.9 L have any kind of bleeders?