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.

Wait! Don't buy another car without the mechanic's checklist that's included in Tom and Ray's pamphlet "How to Buy a Great Used Car: Secrets Only Your Mechanic Knows." It will help you get a good used car and avoid the clunkers. To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 1999 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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