Loud pop when backing up with wheels turned

I have an 06 Ford Expedition 2WD with 97,000 miles. Whenever I am backing up with the wheels turned hard to the right (such as backing out of a parking space) there is a loud pop on the driver’s side after about 1/2 to 1 full wheel revolution (I am guessing about that part but that seems about right - the point is it’s not real far). When I drive forward with the wheel turned the same way there is a similar sound, though less distinct. I have not heard it with the wheels turned left, and the sound only happens when the wheels are turning and it is one distinct pop (no grinding or clicking or anything, just one pop) on the drivers side. I have read guesses that cover pretty much every component on the front end. Anyone willing to offer a definitive guess?

My vote is a CV Joint

The first thing I would check is a wearing outer CV-joint on the left halfshaft. When turning hard the CV-joint is being articulated to it’s maximum angle. And if there’s a ball worn where it hooks the cage at this position inside the CV-joint it can make a popping sound.


Assuming your car is front wheel drive, I agree w/the above posters. The first thing to do is to have your mechanic check to see if the left-outer CV boot has ripped. This is a classic CV joint symptom. And your car is the right age for this to happen.

For front wheel driver owners, it’s a good idea to visually check the integrity of the CV boots every so often as part of routine maintenance. Especially the outer boots, the ones closest to the wheels. If a boot rip is caught in time , only the rubber boot needs to be replaced rather than the entire half-shaft.

GeorgeSanJose you said, “Assuming your car is front wheel drive.” It is rear wheel drive. Does that change the diagnosis?

@JosephEMeehan @Tester @GeorgeSanJose - It is rear wheel drive. Does that change the diagnosis?

I missed the two wheel drive description. Lower ball joint!

Place a floor jack under the lower control arm on the drivers side and jack the vehicle up until the tire is off the ground 4"-6". Place the end of a 4’ long 2X4 under the tire. While someone looks at the lower ball joint with a flashlight, pry up on the tire and let it drop. If the ball joint is worn, the person with the flashlight will see the ball and stud of the ball joint move up and down in it’s socket.


Since it’s rear wheel drive I’d jack that corner up and try wiggling the wheel and watch for play in the hub area. This would indicate a bad wheel bearing. Often if wheel bearings are bad they will make a popping or grinding sound and often worse when the wheels are turned in one direction or the other and not noticeable or better turned in the other direction. If the bearing was bad or dry it should be making a roaring noise as you travel down the road at highway speeds. Might also want to check the condition of the tie rod ends and ball joints.

I also missed the RWD part.  I suggest you follow Tester's suggestion.

if the truck is a 4x4 then i would believe to be acv joint but if its just rwd lower ball joint and could be a lbj any way

(Motor Mounts),front wheel drives or rear wheel drive vehicles.Single loud pop from drivers/ passenger side front of vehicle.Multiple popping/clicking( CV axles) for front wheel drives only.

You have replied to an 8 year old thread so I would guess the problem has been solved by now .

Replying late may not be helpful to the poster but can help people like myself looking for help with the same problem. JS