Is it possible for coolant to leak back into the passenger compartment?

Dear Car Talk

Dear Car Talk | Mar 01, 1996

Dear Tom and Ray:

I have a friend who insists that anti-freeze leaks back into the interior
of her car, causing her headaches. She sold the car because of this. Can
this be true, or is it all in her head?

RAY: I hope the anti-freeze isn't all in her head, Mary. But next time
she nods, try to listen and see if you hear any sloshing.

TOM: It IS possible for antifreeze (also called coolant) to get inside the
passenger compartment. And the way it gets in is through a leaky heater

RAY: The heater core is a little radiator that sits underneath the
dashboard. Hot antifreeze from the engine flows through it, and when you
turn on your heater, that's where the heat comes from.

TOM: And when heater cores get old, they sometimes leak. And when they
leak, anti freeze can be released into the passenger compartment. Anti
freeze has a slightly sweet odor, and sometimes produces a slimy film on
the inside of the windshield.

RAY: And one alternative is to have the heater core replaced And depending
on the car (and how hard it is to get at the heater core) that'll cost you
between $100 and many hundreds of dollars.

TOM: But I like your friend's solution. Selling the car is certainly
another way to get rid of the problem!

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