Car Talk: Differential may have Jeep whining instead of purring

Dear Car Talk:

In high school, I drove a 1946 CJ2 Willys Jeep. In 1992, I upgraded to a 1948 model and used it for construction hauling. I’d put the windshield down and use it to carry all sorts of materials, including 24-foot 2x12s.

Now in my 70s, I had the Willys fully restored, but it makes a loud whine that the restore guys can’t figure out. The transmission was replaced, but when I step on the clutch while cruising at a speedy 35 mph, the noise stops. Someone suggested the “throw out” bearing.

Living in the San Antonio area, there are a lot of former military, like me, who love to see the Jeep, “Arnold,” on the streets with me waving. Sad to hear the loud whine instead of the purr I know he could be making.

Love your column. Have any ideas for me? — Maj. Pete

I love the image of you carrying 24-foot-long boards, Pete. Did you ever consider entering the Jeep Pole Vault Competition?

I don’t think it’s a bad “throw out” bearing. That would make more of a clicking or flapping noise when you step on the clutch. Your noise does the opposite. It stops when you step on the clutch.

It sounds to me more like a bad differential. That’s the classic source of a siren-like whining noise while accelerating.

When my late brother Tom’s differential started going bad in his 1967 Suburban, he hid in the basement for two weeks. He was convinced the cops were following him everywhere.

A differential noise will stop when you let off the accelerator — or when you depress the clutch. Try leaving the clutch alone and lifting off the gas. If that makes the whining noise stop — or sound significantly different — then the gears in one of your differentials could be worn out, or a differential may have run out of oil.

If the noise doesn’t stop when you lift off the gas but only when you step on the clutch, the next step would be to put the Jeep on the lift. If you can duplicate the noise on the lift with an assistant “driving” the car, it should be very easy to walk around underneath the car and figure out where the noise is coming from. And you’ll have to hope it’s not the transmission.

But if it is, I hear the 1949s were really nice, Pete. Good luck.

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