Symptoms:
A crunching sound from the front end of the vehicle when a) the vehicle accelerates from start and b) I turn the wheel for a sharp turn. Has not occured while driving
The crunch seems to becoming more and more frequent (2 times out of 5 start-and-turn occasions)
Yesterday, I lost traction for a second or so during the crunch as if the front wheels lost power
I had the front end checked (suspension etc) twice and everything is ok
What could be the cause of this ?
Car info:
2013 Impala (with the 315 hp engine)
mileage : 140 000 kms (85 000 miles)
Are the tires the proper size for the car? Or are they larger? If so, they could be hitting the inner fender panel or other things as you turn to close to full lock.
My other thought is the CV joints. They may look OK but could be failing internally. The 3rd thought is wheel bearings but these don’t usually crunch, they growl.
Did you take it to 2 different shops? Or the same one twice? If the latter, you may want to take it to another shop.
The tires are Ok I’m pretty sure. Had them for about 3 years
I had the car checked twice by two reputable mechanics (one in Florida, another in Ottawa). Both said they checked everything that could cause that crunching sound and saw nothing defective. Of course, they didn’t hear the sound itself because then it only occured every few day when they checked. Now its much more frequent,
I am more and more inclined to think it has something to do with the transmission of power, ie transmission
Thanks for your interest and help.
Switch off the traction control, then you can spin the wheels without the noise and hesitation of the traction control kicking in.
I’m guessing the suspension system. I understand it has already been checked, but there could still be a problem. For example a broken strut spring is often very difficult to diagnose via visual inspection. A car is constructed sort of like a bobble head doll. When you accelerate, the wheels push forward, but the body of the car lags behind. This causes the rear suspension to drop, and the front suspension to rise. Turning does the same thing, only right vs left rather than forward vs rear. Ask you shop to do a bounce test, where they grab hold of each corner of the car one by one and rock it up and down vigorously while listening for the noise.
Thank you for this information.
I love this car and hope I can keep it. Goes like the wind, smooth as silk, cavernous trunk, and cheap on gas !
BTW, I particularly love its “upper fulcrum” tilt steering wheel where it’s the wheel itself that tilts, not the column as in nearly all other cars I’ve seen. I am tall and adjusting the angle of the steering wheel is important. The new Impalas and the Accord and Camry’s do not have this feature. Would you happen to know other makes that has the feature ?
Thanks again. I will share any other information I get
Question : is there anything in what i’ve described that points away from a transaxle issue ?
If there is a loss of traction the Traction Control System will apply the brake on the wheel that is spinning and may reduce the throttle. The brake actuation will be heard as a ratcheting type of noise.
This is from the owners manual;
The vehicle may have a Traction Control System (TCS) that limits wheel spin. This is especially useful in slippery road conditions. The system operates only if it senses that one or both of the front wheels
are spinning or beginning to lose traction. When this happens, the system reduces engine power and
may also upshift the transmission and apply the front brakes to limit wheel spin.
The system may be heard or felt while it is working, but this is normal.
Update: Noise becoming more frequent. For the first time this morning it “crunched” when accelerating straight head and also when backing up
I’ll wait until it becomes predictable and bring it to a mechanic, probably a GM dealer
Thanks again for your help
Update:
The problem is definitely related to the traction control system. I now deactivate it everytime I start the engine and that eliminates the "crunch’. On a couple of occasions when I forgot to deactivate the system, the car itself deactivated it, once with a deactivation of the ABS also
I went to the local dealer and they told me they had never heard of this issue with the Impala. I am to return when the car automatically shuts off the TC system so they can use read the “code”
When I find a time where I can do without the car, I will ride around with the TC activated and hope I get an automatic disconnect.and bring it to the dealer
Problem identifed and solved.
I brought my car to the dealer when the ABS warning light lit up. They found and replaced corroded wiring in the left wheel WSS harness. (300$)
I must say though that the noise I was concerned about was not a rapide “rat-tat-tat…” characteristic of ABS. It was more llike a crunch
But it’s gone, so I’m happy that I can keep my wonderful Impala for many more years, I hope 
Thanks again for your help
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