Dear Car Talk:

I have a 2017 RAM 2500 four-wheel-drive truck that started emitting a whining sound. I took it in to the dealer, and after two weeks they called and said that several techs drove my truck all over town and did in fact hear the whining, but in their opinion it is normal for "those heavy-duty differentials."

I bought the vehicle new, and it has just 11,800 miles on it. It started making the noise only about 3,000 miles ago. Should I accept their opinion, or take it for a second opinion? Have you ever heard of such a thing? -- Joaquin



Oh, I've heard of such a thing. And I know exactly what it is: It's worn or mismatched ring-and-pinion gears in the differential.

It's a common problem in older vehicles. The differential will make a whining or howling noise either on acceleration or on deceleration. Rarely on both. But we usually don't see it until the car gets to 90,000 or 100,000 miles.
 

And once the noise starts, it tends to drive the owners of those vehicles cuckoo. Since you're writing to me, I'm going to assume you have now met that definition.

Assuming that all of your differential fluid didn't leak out, it shouldn't happen on a brand-new truck, Joaquin. And while it's possible that all 2017 RAM 2500s have whining differentials (and if they do, I think the public would like to know about it), it's more likely that yours is faulty.

Here's what you should do: Go back to the dealer and ask him if it's his opinion that "they all do this." If he says "yes," ask him to take a ride with you in another RAM 2500 that he has on the lot.

I'm guessing that the other new RAM 2500 you drive won't have a differential whine. In which case, they don't all do that. And RAM owes you a differential.

If the other RAMs you drive do make a whining sound, then next time you should test drive a Ford, Chevy and Toyota to see if they also all do that (hint: they don't), and buy one of those instead.

Be polite but firm. I think they're trying to get rid of you, when the right thing to do would be to fix your brand-new truck, which has a warranty for exactly this reason. Good luck, Joaquin.