Lovely smell of coolant in cabin

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John Stover

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Hi all, new to the forum. I read through all of the heating threads, didn't see what I needed. Picked up an 01 XLT 5.4 a couple of months ago. Local mechanic sold it to me and it is in excellent condition. Just this week I'm getting the wonderful coolant odor in the cabin. No obvious leaks. Nothing dripping in the garage, no standing fluid on the engine that I can see, and no smell under the hood. Getting steam on the windows of course. Not overheating, no loss of fluid (or extremely slow loss). Blows good heat. Just gotta find the source of the odor. I suspect heater core, but would like to hear from others. Could it be heater hoses? Thanks for any ideas. I can do a lot of work myself, but know when to get pro help.
 

stamp11127

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Check where the hose connects to the inlet/outlet of the heater core by reaching up and wiping your fingers at the end of the fitting. If you are lucky it is just a leaky o-ring. If not then it will be the heater core.
 

1955moose

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Unfortunately you've got all the tell tale signs of a failing heater core. Steaming of windows along with the sweet coolant smell inside of cabin, are the usual signs. If you put a piece of cardboard or paper on floor inside your SUV, you will probably see a wet spot of coolant, especially when operating heater. The core is cheap enough, theirs a lot of labor involved though.


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JamesRG

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John, I'm also new to the forum with a similar issue, although no fogging of windows. Picked up a 98 Expedition last weekend and the front air vents are blowing warm with coolant smell. The rear AC blows clean and cold. I think it might be the front heater core but I'm not seeing any leaks or wet spots on the front carpets under the dash. The only thing I could locate that might be the culprit is the pipe coming out of the radiator is green at a coupler down which looks like a slow leak.

If anybody has had this issue and can reply with some knowledge that would definitely help this YouTube mechanic!
 
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stamp11127

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JamesRG, heater core plain and simple.
Do you know how to check for voltage present in the cooling system? Usually if the heater core is ate up from electrolysis the radiator isn't too far behind it.
 

JamesRG

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I do not but I have some friends that do and are willing to help. The temp has stayed steady at normal with no overheating. No other places I can find that leak. I did notice if I kept the AC on normal it would stay blowing cold but with coolant smell. When I kicked it to max AC is when it clicked over and started blowing heat. I'm thinking of bypassing the heater core for the time being since I am in central Texas and the front heater isn't that essential. Hopefully the radiator holds up but I can replace that myself if it doesn't. The heater core replacement looked like a weekend chore!
 
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stamp11127

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The heater core isn't that bad if you have the tools and a cordless impact. The only real headache is the shear number of fasteners. It took me about 7 hrs total working on and off. Also you don't have to remove the dash from the vehicle, just swing it out of the way and let the seats support it.
If you bypass the core you will lose most of the defrosting on the front windshield. It may still clear but take a very long time in doing so.

If you decide to swap the core and radiator make sure you use distilled water when mixing the coolant from concentrate.
 
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John Stover

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Thanks to all

I appreciate all of the information. Dang it, a heater core should be a simple job! But then, look at the spark plug replacement issue.... jeez.
Anyway, I took a chance and added some of the best radiator leak sealant I could find. Kappa, I think the name was. Small bottle, about $13. Took a couple of days, but no smell, no steam, no problem. I know it's a temporary fix, but it was certainly worth it. I will find and fix the problem, probably in the spring.
Thanks again to all of you.
 

JamesRG

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I'm thinking of going that route, John, to see if it fixes it at least temporarily. I still cannot for the life of me find the leak. No drips on anything in the engine compartment and no sign of drips or leaking onto the floorboard.

The front heater now doesn't blow warm instead stays whatever the temp is outside. Could that be a clog since it's not getting through the heater core to warm up? And maybe there is a small leak at the connection to the heater core that's only dripping inside the compartment and not enough to drain out onto the floorboard?
 

JamesRG

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I convinced myself yesterday that there was no clog at the heater core and put in an 8oz bottle of K-Seal for $15. Within 5 minutes of driving it the coolant smell was gone and the heater was blowing hot again out of the front vents. Not sure how long this temporary fix will work but for now it's good!
 
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