TOM: Well, we apologize that the Internet has made us virtually inescapable anywhere on the planet. You have our condolences.
RAY: I’m guessing that the reason you’d want to keep passengers in the car with the engine running while changing a tire is for their comfort and/or safety, right?
TOM: Since it’s a rainforest, they stay dry in the car, and possibly air-conditioned, too. And inside the car, there are no ring-tailed lemurs swinging down out of the trees to steal their Papa Gino’s.
RAY: In any case, the primary danger during a tire change is that the vehicle will slip off the jack and injure the tire changer. So the most important thing you can do before changing a tire is secure the car and make sure it doesn’t move. Anything that increases the chances of the car moving should be avoided.
TOM: So if the vehicle has an automatic transmission, there’s no reason you can’t leave it running while you change the tire. You’d put it in park, apply the parking brake and chock the wheels (you’d wedge a large rock or a piece of wood in front of a front tire and behind a rear tire) to secure the vehicle.
RAY: If, on the other hand, the vehicle has a manual transmission, running the engine eliminates your ability to park it in gear. So all you’ve got is the parking brake and the wheel chocks.
TOM: So if it’s a manual transmission, here’s what I’d do: You can leave the engine running while the tire changer prepares the spare tire and gets the jack in place. You can even leave it running while he breaks loose the lug nuts and gets them started.
RAY: But once he’s ready to jack the car off the ground, then you should turn off the ignition, put the transmission in first gear or reverse, and inconvenience your passengers for a few minutes while the wheel is actually removed and replaced. They’ll survive. Once the car is back down on the ground, then you can take it out of gear and start the engine again.
TOM: And needless to say, whether the engine is running or not, you want your passengers to sit relatively still. You don’t want them rocking back and forth to a rousing rendition of “99 Bottles of Beer on the Wall” while the car is off the ground. Good luck, Kelly!
Is this guy the idiot, or are Tom and Ray?
Dear Tom and Ray:
You recently answered a question about whether it’s harmful to let your gas tank run down to empty. You said it’s not harmful to the car, and it won’t cause any damage. Eric Peters, a Washington, D.C.,-based automotive columnist, recently stated in the periodical Bottom Line/Personal that, and I quote here: “Most gas tanks are made out of metal, and a partially empty fuel tank is prone to rust. Rust particles flake off and can clog fuel filters, fuel lines and fuel injectors, leading to costly repairs. In addition rust can eat through the tank, causing leaks ...”
So what gives? Are you two right and still my heroes and this guy is an idiot, or is he right and you two are idiots? A curious reader wants to know. — Fred
RAY: Well, you already know we’re idiots, Fred. But in this case, Mr. Peters’ information is badly out of date.
TOM: In the old days, when tanks were metal and were vented to the outside air, rust and other particles were a problem. That’s why cars had fuel filters — to keep that stuff out of the fuel lines and injectors.
RAY: But for more than a decade now, most fuel tanks have been made of plastic. Even the fuel lines that carry the gasoline from the tank to the engine are now plastic.
TOM: Rust is such a non-issue now that most cars don’t even HAVE fuel filters anymore. There’s a “sock” filter on the fuel-pump intake in the tank — in case an irate neighbor pours a plate of stuffed clams into your tank — but that’s it.
RAY: Plastic fuel tanks have a number of advantages: They weigh less, they’re cheaper to produce and they don’t rust.
TOM: And they may be better in accidents, too.
RAY: For a while, running the car out of fuel concerned us, because the fuel serves as the coolant for the fuel pump — which sits at the bottom of the tank. But we really haven’t seen any problems with fuel pumps to justify that concern.
TOM: So our opinion is, it’s fine to run the car down to empty. If that makes you happy, go for it. Just don’t call us to pick you up when you run out of gas, Fred.
Send your comments or questions for Tom and Ray to: Car Talk Plaza, Box 3500 Harvard Square, Cambridge, MA 02238. Listen to them every Saturday at 10 a.m. on radio stations 91.3 FM or 88.5 FM or Sunday at noon on 88.5 FM. Visit them on the Internet at www.cartalk.com.
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