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Discussion Starter · #1 ·
I sometimes get a coolant leak, I can smell it from the inside. On the driver side floor, has some antifreeze (not a lot). But also there is a small leak outside underneath by the passenger side. Just next to the drip of the A/C condensation.

What to make of it? Is it a heater core? Heater hose? Or both.
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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Always diagnose first. I have had heater hose clamps crack and leak also.
There may be access to look inside the HVAC housing by the glovebox?
 
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Hook up a coolant system pressure tester. Makes it a lot easier to find the source of the leak.
 

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And you do have the option of bypassing the heater core, just connect a loop of heater hose from engine take-off and return. Of course you won't have any heat, but if the leak gets worse, and you don't have the time and/or money to do that lengthy and costly replacement job right away, you can keep the vehicle running that way for a while.
 

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Discussion Starter · #6 ·
Always diagnose first. I have had heater hose clamps crack and leak also.
There may be access to look inside the HVAC housing by the glovebox?
If that is the case (let's say) then it's possible for the heater hose to cause a leak to the interior?
 

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Driving down the road, the engine compartment is a high-pressure area with air blowing through the radiator.
This will tend to force odors and leaks, etc. into the low-pressure passenger compartment where-ever it can enter.
Coolant leaking from a heater hose end at the firewall can have coolant pushed into the heater box or interior. I have seen it before and it is worth ruling out first.
It is a very slow leak whatever it is and a coolant pressure tester may not show a pressure drop for a long time. You really have to look for the wet spot.
There may be a rubber grommet for the evaporator temp sensor by the glovebox that can be pulled off the HVAC housing for a peek inside the housing. The wires for the temp probe are fragile, so avoid pulling on them.
 

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In earlier Mopars, this problem was often caused by a faulty heater control valve. Don't know if it's what's causing yours, but check that first before replacing the heater core.
 

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If that is the case (let's say) then it's possible for the heater hose to cause a leak to the interior?
Usually there is a flimsy foam seal between the firewall opening that the heater core tubes go through, and broken or loose clamp on the hose would cause it to leak right at the opening. Its very possible for a leak like that to get the coolant into the interior of the vehicle, like IC suggested.

Changing the heater core is a "HUGE" job, personally I would check every possibility before tackling it. I hate to go to all the effort and expense to find out it was just a broken clamp all along.

Check it often, I'd have to agree if the tubes/clamps/hoses near the firewall in the engine compartment are always dry while its leaking in the interior from the HVAC box, its got to be a leak inside the HVAC box.

Some vehicles the heater core is located quite a distance from the openings in the firewall and have a separate section of tubes, with seals that connect to the heater core in the interior. (I imagine the engine compartment is so crowded, they have to move the hose pick-ups). Look for diagrams or repair guides with illustrations to show the make up. My guess a Dakota of that era would be simpler, but you never know.
 

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Discussion Starter · #10 ·
Usually there is a flimsy foam seal between the firewall opening that the heater core tubes go through, and broken or loose clamp on the hose would cause it to leak right at the opening. Its very possible for a leak like that to get the coolant into the interior of the vehicle, like IC suggested.

Changing the heater core is a "HUGE" job, personally I would check every possibility before tackling it. I hate to go to all the effort and expense to find out it was just a broken clamp all along.

Check it often, I'd have to agree if the tubes/clamps/hoses near the firewall in the engine compartment are always dry while its leaking in the interior from the HVAC box, its got to be a leak inside the HVAC box.

Some vehicles the heater core is located quite a distance from the openings in the firewall and have a separate section of tubes, with seals that connect to the heater core in the interior. (I imagine the engine compartment is so crowded, they have to move the hose pick-ups). Look for diagrams or repair guides with illustrations to show the make up. My guess a Dakota of that era would be simpler, but you never know.
I will definitely look into it. Checking all the hoses, clamps first That would be a big relief if it is a simple leak other than the heater core because that would be a nightmare. I would not attempt the job of replacing the heater core myself, and how expensive it would be for a mechanic to do the job.
 

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On the previous generation Dakota it was a $600 to $800 job.
I doubt the 2005 is any easier than the 1997-2004 design.
 
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