‘Whistling teapot’ sounds could mean a steep mechanic bill

Dear Car Talk:

I have a 2002 Jeep Wrangler Sport. It's in great condition, but it's making a noise I cannot live with. After a few miles on the road, it starts to make a "teapot" whistling noise. When I press on the gas, it goes away, but as I release the gas, it starts again. Any idea what it is? – Becki

RAY: Unfortunately, yes. Well, if you're really lucky, it could be something as simple as a vacuum leak. But in that case, Becki, you should be able to duplicate the noise by pulling over and revving the engine with the car in park. If you hear the noise only when the car is in motion, then I'm afraid it sounds ominously like differential whine.

My brother had an old Chevy Suburban, and for months he kept pulling over on the highway, thinking there was a cop behind him blaring his siren. Turned out it was the differential.

The differential is a simple box of six gears that – through some sort of magic we mortals don’t understand – allows the wheels to turn at different speeds. Why do they need to turn at different speeds? So the car can turn. If you take a Matchbox car, paint the wheels black and then drive it in a very tight circle on your kitchen table, you’ll see from the tracks that the outside wheels travel farther than the inside wheels. And since all the wheels arrive at the same time, the outside wheels must be turning faster. The differential is what allows the rear wheels, in your case, to get power while turning at different speeds.

By the way, sorry about your kitchen table.

Anyway, Becki, what you’re describing are the classic symptoms of a failing differential: a howling/whining noise that changes depending on whether you’re accelerating or coasting.

Unfortunately, you have two differentials on this car (because it’s four-wheel-drive). The most likely scenario is that the damage has already been done, and one of the differentials has gears that are worn out.

But before you jump to that conclusion, there’s one thing you can try: Have a mechanic check the differential fluid. If by some chance one of the differentials is low, and it hasn’t been low for too long, you can try filling it back up.

If the noise goes away after that, trade in the car immediately, while it’s quiet. Good luck.

Safer options than old car for making regular long trips

Dear Car Talk:

On my way to Florida from Rhode Island, my radiator overheated and I was towed to a garage in the Bronx. Two days and $2,700 later (see repair slip), I was on the road again. Needless to say, that was a shock. My car is a 1996 Cadillac Eldorado, and I am trying to keep this old car on the road, as my mechanics in both states tell me it's worth it. I would like your opinion, as I'm 83 years old and my husband died in January. Should I get rid of the Caddy and lease a cheaper car? Thanks. – Ruth

RAY: I think when your mechanics told you it's worth keeping this old car on the road, they meant it's worth it for THEM.

First of all, I’m afraid these fine chaps in the Bronx took you for a ride. In my estimation, they charged you somewhere between $800 and $1,200 more than they should have for a radiator, water pump and coolant sensor – assuming you even needed all that stuff. They saw you as an easy mark, Ruth. And shame on them.

But that’s radiator fluid under the bridge now. The question is, what should you do going forward?

The problem with a 22-year-old car is that it can break down at any time. And if you’re using it to travel between Rhode Island and Florida, it’s very easy for you to end up in a similar situation: at the mercy of a mechanic you don’t know, with no other recourse.

So I have a few ideas for you. One is your own idea, to lease or buy another car. A new car is statistically much less likely to fail on you. And even if it does, you’ll be under warranty for the next few years. If you do opt for a new car, make sure you get all the latest safety features we’ve been recommending (automatic emergency braking, blind-spot monitoring, etc.).

Another option, if you really love this car, is to let someone else move it between Rhode Island and Florida for you. There are car transport services that will put your car on a carrier and deliver it to you in a matter of days. And while your car is being trucked down Interstate 95, you’ll be eating free peanuts at 35,000 feet and making the trip in two and half hours instead of two and half days. And that way, the next time the Caddy breaks down, you’ll be near one of your two homes, where presumably you have mechanics you trust.

A third option would be to keep the Caddy in Rhode Island, and buy a good used car and leave that one in Florida (or vice versa). If you leave the battery connected to a trickle charger (also called a battery tender), the car ought to fire right up for you when you arrive.

But I’d love to see you stop making that 1,500-mile drive in a 22-year-old car twice a year, Ruth. That’s a long drive, even if you stock up on 8-track tapes. Good luck to you!