QDear Tom and Ray:

I love your column, guys. I'm curious about a rerun of "MacGyver" that I saw last week. He was trying to escape from "San Arugula" or someplace south of the border. He found an abandoned jeep, and of course got it to fire right up. However, the radiator was riddled with bullet holes, so he thought he was a goner. Then his little light bulb went off. He stole some chicken eggs from a nearby farm, and with the engine running, he proceeded to separate the eggs, putting only the egg whites in the radiator. Voila! The leaks were sealed, he escaped, and he once again saved the world. My obvious question: Would that really work? I know you're laughing, but you have no idea how many things I've "MacGyvered" with paper clips, so who knows? Just wondering if I should keep a few eggs in the toolbox. -- Ruth

ARAY: Actually, it might work. Here's the theory: If there's a small hole in the radiator, the water or coolant is going to escape through that hole. When you dump in the egg, it goes in as a gooey liquid. But as it travels through the hot fluid (note: engine running), it cooks and hardens. And if everything works just right, the egg is dragged toward the hole, hits it, hardens up and plugs the leak.

TOM: That's the theory. People have also used pepper flakes for this repair, which I also keep -- along with the eggs -- in my toolbox. Even if I don't have a radiator leak, it's nice to know I can always whip myself up a half-decent breakfast.

RAY: The egg trick can actually work, Ruth, as a temporary fix, if the hole -- or holes -- are small enough.

TOM: But I'm afraid it won't work on bullet holes. The radiator is not a single tank that holds water. The part of the radiator that holds the coolant is made up of a bunch of thin metal tubes. Those tubes carry the coolant slowly from one end of the radiator to the other. It's during that journey that the heat is removed.

RAY: But those little tubes are only about an eighth of an inch wide and an inch deep. And if a bullet blows through one of those tubes, it's going to literally tear it in half, leaving a 38-millimeter gap between the two remaining pieces. And even a Western omelet won't fix that.

TOM: I suppose that if a bullet just grazed a tube, it might still work. So, let's assume, for the sake of MacGyver's reputation, that the hail of bullets just nicked one of the cooling tubes. Otherwise, that would have been MacGyver's last episode.

Dear Tom and Ray:

I'm having a problem that just started recently. When I start the car, it takes a while for the engine to warm up. If I sit there, eventually the temperature gauge will go up to normal. But once I start driving, it goes back down to "cold," and cold air comes out of the heater. Turning the heat on causes the engine temperature to drop even faster. It is freezing in the car! I took out the thermostat and tested it, and it is working properly. I changed the heater core, too, and the water pump is new. Can you tell me what else I can look for or test? -- Joe

RAY: Your symptoms are pointing in your thermostat's direction, Joe. They're textbook. Your thermostat is stuck in the open position, and it's never letting the engine get up to operating temperature.

TOM: So your coolant is always circulating through the radiator. And when you drive, cold air blows across the radiator and cools it off even more.

RAY: Running the heat cools off the engine, too, since the heater core is really another small radiator.

TOM: So pop a new thermostat in there, Joe, and your problems should be solved. And chalk up the cost of the new heater core you installed to an expensive lesson in how to work upside down while lying under a dashboard.

Got a question about cars? Write to Click & Clack in care of The Post, or e-mail them by visiting the Car Talk Web site at www.cartalk.com.

(c)2004 by Tom and Ray Magliozzi

and Doug Berman