Dear Tom and Ray:

I have a 2003 Ford Explorer Sport Trac with only 22,000 miles on it. I took it to my local quickie-lube place for an oil change. They offered to do a free alignment check. My boat-payment antennae went up immediately. They said the lower ball joints were worn and needed to be replaced. It drives like the boat it has always been, and I've noticed no unusual tire wear. How likely is it that the ball joints are worn? Is there any significant risk to not getting them replaced? Would I notice any indications that they're failing?

-- John

TOM: Very, yes, and no.

RAY: On a 10-year-old car, I think it's very likely that your ball joints are worn out, John. Even though you have low mileage, the grease inside the joints tends to dry up, and that causes the joints to fail.

TOM: If you don't trust these guys, the easiest way to confirm this is to take the car to another mechanic and ask for a second opinion. If you don't have a mechanic you trust (which everyone should), try searching at www.mechanicsfiles.com. That's a nationwide database of good mechanics who have been personally recommended by other readers and listeners of ours.

RAY: It's unlikely that you'd be able to determine, by driving the car, whether your ball joints are bad. You won't feel anything until it's almost too late. Just before the ball joints break, you may feel a shimmy in the wheel and have time to say, "Hm, what's that?"

TOM: But your mechanic can tell by testing them. He'll put the car up on the lift and grab each tire at 9 and 3 o'clock, and try to push and pull it. He'll do the same thing at 12 and 6 o'clock. If the ball joint is good, there should be absolutely no back-and-forth movement in the wheel whatsoever. If it moves at all, the ball joints are shot and you need new ones.

RAY: And what if you just wait, John? Is there a significant risk? Well, how does this sound: You're driving at 70 mph, and all of a sudden you feel a strange little shaking. As you furrow your brow to wonder what's causing the vibration, your wheel falls off.

TOM: Then, as your life is flashing before your eyes, you can quietly apologize to the guy who tried to tell you that you needed ball joints. So get the second opinion if you don't trust this guy, but don't just ignore the warning.