Dear Tom and Ray:

We have a '97 Ford Escort with 19,000 miles. Recently, we've noticed the strong smell of exhaust coming in through the air conditioner or heater almost every time we come to a complete stop. This only happens when we have the fan on with the vent intake open. I have to switch the air off every time I come to a stop in order to avoid this. We also notice the smell from the front seat when we have the windows rolled down. My wife confessed that she ran over a concrete parking barrier recently, and she feared there was some damage underneath. I took the car to our local Ford dealership and then to a national muffler chain. Neither of them found anything wrong. They both suggested I spray air freshener in the air vents. The smell is definitely exhaust, and we're concerned it might be dangerous. -- Greg

TOM: We're concerned, too, Greg. As you might know, one of the early symptoms of carbon-monoxide poisoning is confusion and poor judgment. And look -- you've already written to us for advice!

RAY: You clearly have an exhaust leak, Greg. And it probably IS the result of your wife hitting the parking barrier. The front pipe of this car's exhaust system runs down from the engine under the front of the car, and it probably got jolted, creating a small leak somewhere. And the leaking exhaust is wafting up through the engine compartment and entering the ventilation system through the cowl in front of the windshield.

TOM: And last time we checked, Lysol does not neutralize carbon monoxide (shame on those bozos for suggesting that). You need a mechanic who is willing to take a little time to find the leak.

RAY: If it's a very small leak, the best way to pinpoint it is with an emissions wand -- the kind that's used in state emissions tests. The mechanic passes the wand around inside the engine compartment, and when the needle goes bonkers, he's found the site of the leak.

TOM: Find someone who's willing to find this leak for you and who'll fix it, Greg. And in the meantime, if you catch yourself calling our radio show, seek medical attention immediately.