Author Topic: 1999 Chevy Blazer - smelling antifreeze / heater core issues  (Read 4750 times)

quillan5

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1999 Chevy Blazer - smelling antifreeze / heater core issues
« on: October 09, 2011, 11:39:43 AM »
1999 Blazer, 4.3L w/ 145,000 miles:

A few days ago I started smelling antifreeze when I ran the heater. Assuming it was due to a bad heater core, I had it replaced. The mechanic (a friend) put a new core in, but showed me the old core and there was no sign of it malfunctioning - no leak, no antifreeze residue or anything.

Since he put in the new core, the problem is worse than ever. The smell of anti freeze is much stronger. And when I turn on the defroster, I can even see a light, greasy film build on the inside of the windshield after a little while. So I basically have two questions:

1) What might have caused the original smell of antifreeze if the original heater core was in good shape? (Could the smell inside the cabin come from a different source than the heater core?)

And 2) What may have made this situation even worse after putting in a new core? I have a theory on number 2, but I would like to get the forum’s take. Any responses will be greatly appreciated.

Linkback: http://www.trustmymechanic.com/forum/b1/1999-chevy-blazer-smelling-antifreeze-heater-core-issues/38183/

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conniecartech

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Re: 1999 Chevy Blazer - smelling antifreeze / heater core issues
« Reply #1 on: October 09, 2011, 01:37:36 PM »
hmm, this is kinda a strange one, but ill take a shot at it  Very Happy

u cant allways find a coolant leak by looking at it. it only takes a tiny pinhole leak to squirt it out when the system is warm and under pressure. the core would need to be pressure tested to know for sure if its leaking. one weak spot on lots of heater cores is where the tubes come in thru the firewall and attach to the core body. sometimes that joint can get a tiny stress crack and start leaking.

as for why the smell is worse now, it could be that when he took the old core out, coolant from inside it spilled out of the core into the core case. or its even possible that the new core is defective, again most likely where the tubes join the core body. either way, a puddle of coolant in the case can cause the film on the windshield in defrost mode.

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quillan5

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Re: 1999 Chevy Blazer - smelling antifreeze / heater core issues
« Reply #2 on: October 10, 2011, 07:52:13 AM »
Regarding your response: "as for why the smell is worse now, it could be that when he took the old core out, coolant from inside it spilled out of the core into the core case."

If this has happened, will the pool of coolant dissipate? Wondering how I could eliminate the antifreeze and smell.

Thanks!

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conniecartech

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Re: 1999 Chevy Blazer - smelling antifreeze / heater core issues
« Reply #3 on: October 10, 2011, 12:28:16 PM »
on some vehicles the heater core and a/c evaporator is in the same case, so any coolant in the case will drip out of the drain just like condensation from the evaporator. but on yours, the heater core and evaporator is in separate cases. unfortunately that means to check it, the heater core case would need to be opened back up. if there is coolant in there it would need to be cleaned out and dry before its put back together.

coolant evaporates much slower then plain water. that plus the core case being sealed, means it would take forever for it to dry out. eventualy it might, especialy when u run the heater or defroster, but u would have the odor and windshield fogging for a long time.

keep in mind that coolant puddling in the case is just a idea. i cant say i actualy seen this exact thing before. but thats the only thing i know of that can cause the odor and fogging. if u do end up getting in there again, check the new core carefully to be sure it aint leaking, as i mentioned in my earlyer post.

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quillan5

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Re: 1999 Chevy Blazer - smelling antifreeze / heater core issues
« Reply #4 on: October 10, 2011, 01:42:03 PM »
Thanks conniecartech.

I have a couple more questions:

As one option for a remedy, my mechanic (a friend) said he could use a heated piece of metal to burn a drain hole into the bottom of the case (because drilling might damage the core). So question 1) What is your take on this? (Could it work, or would I still end up with the odor and fogging?)

2) How can I tell if the new core itself is defective? If the core is leaking, wouldn't it just collect in the case, or would it somehow overflow to somewhere?

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conniecartech

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Re: 1999 Chevy Blazer - smelling antifreeze / heater core issues
« Reply #5 on: October 10, 2011, 03:49:18 PM »
1. first, double check to make sure there aint a drain hose. if not, this idea could work. the hole would have to be at the lowest point on the case. but even then it may not drain all the coolant out, and youd have to leave it open til the left overs evaporated. while its open hot air would come out the hole, which would reduce the efficiency of the heater and defroster. then, youd have to be sure to seal it up real good, to prevent hot air from escaping.

before making a hole, u may wanna see if u can loosen the screws on the bottom of the case and seperate the halfs a little. if theres any coolant in there it should come out.

2. the core would have to come out for this. without adapters and a way to pressurize it, a workaround would be to empty as much coolant as u can from the core, then dunk it in a bucket of water, with the tubes pointed up and the ends of the tubes above the water surface. then check carefully for realy tiny air bubbles coming up from the core. if u see this, that points to a leak. if u can blow some air into one of the tubes, that could make it easyer to see any leaks. btw this allso works for the a/c evaporator core.

if it is collecting in the case, chances are it would find its way out thru any small leaks in the seal between the case halfs, or where the tubes go thru the firewall, or any other place where there aint a water tight seal. if it did build up in the case, airflow thru the core would be reduced or elliminated, and the heater and defroster would not blow air, or blow reduced air, depending on how high the coolant level was in the case.
« Last Edit: December 31, 1969, 06:00:00 PM by conniecartech »

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quillan5

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Re: 1999 Chevy Blazer - smelling antifreeze / heater core issues
« Reply #6 on: October 30, 2011, 05:21:39 PM »
Still have no clue as to the source of the coolant smell in the cabin. Since I installed a new heater core the smell is still very much there. I've run it hot with defrost on daily for 2 weeks and no reduction in the toxic smell. I'm trying to eliminate all other causes before I go in and take apart the entire dash again (thinking maybe the new core leaks, but there's no fluid on the floorboard or no loss of coolant). DOES ANYONE HAVE ANY IDEA WHAT COULD BE CAUSING THIS OUTSIDE OF THE NEW CORE LEAKING OR A POOL OF COOLANT EXISTING IN THE CORE CASE AS A RESULT OF THE NEW CORE INSTALLATION?

Is there any other area the coolant could be leaking where the smell of hot, vapor-like antifreeze would make its way into the cabin? The stuff is toxic.

Thanks for any feedback.

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