When I bought my 88 GT, I noticed it smelled like coolant when the heater was on - replaced the heater core, as the previous one was leaky, not bad, but left residue in the ducting underneath its mount. I wiped out all the ashy residue as far as I could get my arm in, and put the new one in. Thing is, it still smells like anitfreeze, especially on the heater setting with the temp contol up to warm. Seems to smell less pungent when on warm and vent, but still a bit coolant-y. I remember my old 86 GT bursted a core, but I caught it and replaced the next day. Never had residual smell. Is it possible the new core is bad (I've only drilled a small hole under the core to see if water dripped, but it was dry) - or is it possible the plastic had coolant on it for so long it's soaked in and is releasing the smell? I also checked the hose connections to it, and they seem fine. Maybe the new core leaks so little it smells, but evaporates off the core and doesn't drip?

Try this:
- Take a rag and tie it into a small ball that will fit into the duct work with a cord that will be long enough to pull through the ducts.
- Soak the rag with Ethanol
- Pull the rag through the ducts to wipe out a good portion of any remaining anti-freeze.

Ethylene Glycol LOVES plastics. The only way to get the smell out is to clean out the ducts with a solvent. Soaps will work, but they leave their own residues. You've got a job ahead of you. I know in my '68 Camaro, that was THE only way I was able to get rid of that smell. Also make sure the box that actually holds the heater core is cleaned out too.

Good luck!

You've likely got coolant residue in the ducts that was pulled in by the heater fan. I had a similar problem with my van.

I've used this with good success - Wynn's® AircoFresh Odor Eliminator Treatment that stops offensive odours. Treats all components of the HVAC system. http://www.wynnsusa.com/ac.aspx

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World of Wheels Winners
My 3.4L S/C 87 GT
& Super Duty 4 Indy

Removing the dashboard is not that bad once you get it in your head thats what you are going to. The remove the heater box at the heatercore and thouroghly clean it. you should be able to complete this on a Saturday. Much better the breathing crap all the time.

Just a thought

Might want to check your windshield and carpet below the heater core mounting. When my heater core failed, I didn't realize it had failed and my floor mat was drenched with anti-freeze and due to it being on front defrost, it shot anti-freeze all up on the windshield. That stuff is a pain to clean.

It's only like a half dozen 7MM screws to remove the cover, couple of hose clamps, pop it open, clean it out with some Purple Power degreaser which will disolve the anti-freeze. You'll probably need to wipe down the inside around the heater core area too, shouldn't take too long, just a bit tedious, that's all. After I got through cleaning up after a rodent croaked in my duct, I sprayed Lysol into the ducts, that worked fairly well but in your case go with good degreaser.

The last time I replaced a heater core, the air coming through it smelled odd for several months. It was sort of a "metallic" smell which I attributed to the new core. It eventually dissipated.

crap, dead rodent! that must have been awful - would make you wish for antifreeze smell!

I don't even mind the smell so much, but since it's poisonous to drink, I imagine inhaling coolant vapor for an hour each day isn't all that great for you either.

It's been months really, and when I first put a new core in, I ran it alot on heat with high fan even in the summer. If it would eventually go away, I'd just leave it, but maybe some degreaser agent around the core ducting would help...

The smell should have dissapaited after a couple of months. You may have a hose clamp that is loose enough to allow a slow leak under pressure or a pinhole leak in the heater core.

Here's a suggestion on my part, get a cheap bottle of ultraviolet dye marker form eBay or the auto parts store, pour that into your coolant system at your thermostat housing (after raising the back of your car) Let that run for a week or so. Go to the local hardware store or drug store, purchase a black light. You only need the bulb, they call it a party light but it's only like $6 bucks or so. In dark conditions, it will show you exactly if and where you have leaks. I did the same on an old Pontiac LaMans ("the plague") in the crankcase to help me locate oil leaks. I would check every hose on the car as you may have a leak somewhere else and the odor is drifting into the car.

Good luck!

Just thought of something, anti-freeze will kill rodents, wonder if that's what happened to my little "passenger".