Ask Doctor Crankshaft: Suddenly, key won't turn in car's doors. Why?

Last Updated: 8/24/2011 11:22:14 AM

Suddenly, key won't turn in car's doors: what to do?
Q: The key won't turn in my car's doors even though it's the same key I've used for years. How can I unlock the doors to get in? Does something happen to the locks over time or does the key wear out? Can I use a Slim Jim? — Ben in Houston, Texas
A: First, examine the key carefully. If the teeth are worn or rounded, they might not push the lock tumblers far enough to allow the cylinders to turn. This is the most likely situation, since none of your doors can be unlocked with the key. If this is the case, you should have an extra key that came with the car or, if not, the dealer can make a new key from your VIN number.
If the key – or spare key – won't open the doors, you should spray lubricant into the lock cylinders. Corrosion builds up in there over time. Avoid using a Slim Jim, as modern cars have baffles and other devices installed to make their use difficult, if not impossible. You can easily damage lock mechanism linkages by forcing a Slim Jim down inside the door.

Why does car hydroplane on wet roads only sometimes?
Q: Why does my car hydroplane on wet roads sometimes but not others? I can drive on the same interstate every day and when it's rainy, the car's steering might be fine, but at other times, it rides up on the water and hydroplanes a bit. My tires are only six months old and seem fine, so what should I watch for as I drive in the rain? Also, what's the best part of the road to ride on? — Mary in Plattsburg, NY
A: Whether or not your car will hydroplane depends upon the rain’s intensity and the temperature and curvature (crown) of the road surface. In heavy rain (defined as one inch per hour), any road surface will pool in spots and your tires' tread sipes (the grooves cut into the tire’s surface) won't be able to push the water away fast enough. That's when hydroplaning, which is quite dangerous, takes place. You’ll find that on your interstate (three lanes) the center lane has the least chance of pooling because it's at the top of the designed-in crown of the road surface. On other roads, the best way to avoid pooling is to stay as close to the center as possible. The colder the temperature, the stiffer your tire sidewalls tend to be, so hydroplaning is more likely in those conditions because there’s less flexibility in the tread.
A good rule of thumb is that if you have to run your wipers at their fastest speed, it's very likely that you’ll find hydroplaning conditions. If your wipers only need to run on the intermittent setting, you should be able to drive along at reasonable speed, but when it's raining, it's best always to slow down.

How fast have you ever driven?
Q: This is a silly question, but how fast have you ever driven? What kind of car was it, and where did you do it? Thanks. — Phil
A: I've hit 205 mph in a CART open wheel racecar at Las Vegas International and have made runs above 175 in some modern high performance sports cars, but always at racetracks and always in good weather conditions. Going fast is easy but going fast safely takes skill, concentration and making sure the equipment on the car, particularly the tires and brakes, is in perfect working order.
Dr. Crankshaft is automotive writer, radio host and restorer Les Jackson. In addition to writing for newspapers, he's editor-in-chief of www.secondchancegarage.com, the web's first all-restoration subscription site, and co-host of “Cruise Control,” heard Saturdays from 10-noon EST on the USA, National and Cable Radio networks. You can also listen live at www.cruisecontrolradio.com or download podcasts from iTunes. Send your questions to Dr. Crankshaft at DrCrankshaft@AutoWritersInk.com; please include your name and a location.