99 Dodge Ram 1500 heater core?

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My husband's deployed to Iraq and left me with his truck problems - would appreciate any input...

Back in the cold, the truck leaked coolant (I think) into the glove box and though it hasn't done that again, there is still a sweet smell when it's running and the windshield on the passenger side fogs up. Took to the mechanic and told them I thought it was the heater core. They did a pressure test to the coolant system and found no leaks, but I don't know if that would diagnose a heater core problem or not.

posted by  JBanz

The first step in your quest for help is using the "Introduce Yourself" section.

posted by  vwhobo

Sorry for the etiquette breach :oops:

posted by  JBanz

If they did in fact perform a pressure test on the cooling system then it would include the heater core. It is possible that it's still leaking and they didn't see it, it's possible they didn't really do the pressure test and it's even remotely possible that the heater core does have a leak but only during certain transient temperatures. That is the hardest leak to find.

Knowing nothing else about the truck, this is my call. It's entirely possible that when the last heater core was replaced, they didn't clean the coolant residue from inside the heater box. Because the anti-freeze can take a LONG time to evaporate, the residue may be the cause of your problem.

Now for the most important part of the equation. Is the truck using coolant (are you having to add water) or is the level staying the same. If you're not using coolant then you obviously don't have a leak. If you are using coolant you'll need more investigation, maybe by a more qualified technician.

posted by  vwhobo

You can also pull up the carpet on the passenger side firewall floorpan and look for wetness. Look for a bead of antifreeze on the firewall where the heater box is. If it is wet, clean it up and then drive it for a few days, see if there is anymore coolant under the carpet. Heater cores, as VW mentioned, can leak ONLY under a certain type of circumstance. I have a 76 Buick Electra and right now, I have a VERY slight leak if I run the cooling system pressurized. It takes about a day of driving to form a small bead on the firewall. My solution until I decide to pull the passenger dash out to replace the core (which I already have) is to run the cooling system depressurized. This is ONE click on the radiator cap rather than full closckwise. This means you are running vented. It seems to have NO effect on engine cooling nor heating of the vehicle. I have been driving the car like this for about 5 months. With a 76, I do NOT want to damage ANY parts by removing the dash as the availability is VERY hard to find parts.

I know I am deviating a little from your problem, but if we can determine it does have a small leak in the core, you can run it vented for a while until you can have someone look at it. Vented just allows it to run under little to no real pressure so it will not leak.

Another sign of windows fogging is water leaks.....Have you pulled back the carpet recently? Cowl induction is a MAJOR source of leaks on MANY cars as well as door seals where the floor pan actually drops down from the door seal edge. Chrysler and Jeep(now Chrysler) are FAMOUS for water leaks. I have spent more time resolving these types of issues of several of my cars and you talk about a job to do. If you own a Jeep, Chrysler or any GM, you might wanna pull back your carpet and take a peak......it would not surprise me to have you find soaking wet underpadding with can lead to a slew of issues including smells, rotten floor boards and windows fogging.

posted by  cmeseadoin

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