Before replacing your heater core again, check your thermostat.

Dear Car Talk

Dear Car Talk | Mar 01, 1999

Dear Tom and Ray:

I have a 1985 four-cylinder Ford Mustang. Recently, I noticed the unmistakable
smell of coolant inside the car and realized my heater core was leaking. Having
already replaced it once, and being short of cash, I merely disconnected the
hoses running to the heater box on the fire wall. I left the metal pipes,
including the one that I think has the radiator fan sensor. Now, I have no more
smell and no more leaking coolant. However, the car seems to be running cool.
The temperature gauge barely gets off "C." Is there any way I could have
affected the engine temperature by bypassing the heater core? -- John

TOM: Yes, but you would have affected it in the other direction.

RAY: Right. Since the heater core (the thing that provides heat to the passenger
compartment) is actually an extra little radiator, it helps cool the engine a
little bit when it's in use. Removing it from the circuit would make the engine
run hotter, if anything.

TOM: So I have to believe that the timing is just coincidence, and what you need
is a thermostat, John. Try swapping out the thermostat, and write us back if the
problem doesn't completely go away.

The annual cost of owning a good used car is about half as much as owning a new
car! How do you find a good used car? Order Tom and Ray's pamphlet "How to Buy a
Used Car: Things That Detroit and Tokyo Don't Want You to Know." Send $3 and a
stamped (55 cents), self-addressed, No. 10 envelope to Used Car, PO Box 6420,
Riverton, NJ 08077-6420.

?(C) 1999 by Tom and Ray Magliozzi and Doug Berman
Distributed by King Features Syndicate, Inc.

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