Help with strange noise, fluttering
07-28-2020 | 09:31 AM
#1
Thread Starter
Newbie
Joined: Nov 2010
Posts: 3
Likes: 0
15 C300, 16 Tesla Model S, 2004 Cayenne Turbo
Help with strange noise, fluttering
Hi all,
I'm hoping someone can help me diagnose the problem with my 2015 C300 4matic with 98,000 miles. The tires are fairly new with less than 3000 miles. The front brake pads are good.
I have a light tapping/knocking/fluttering only when the car is moving. The speed can be fast or slow. It is not loud enough to overcome the stereo, but moderately loud outside. I can clearly hear it when driving beside another car with the window down.
I would describe it as an object touching a moving fan. I think it is coming from the front. I can't determine if it is coming from one side or the other.
In steady speed driving, it will speed up and slow down in a seemingly random manner, or even stop. I can sometimes manage to make the noise stop by adjusting the throttle pedal. It happens in acceleration and in deceleration.
My first thought is that it was related to a CV joint or the front drive axle. I jacked up the car and couldn't find anything alarming except, that there seems to be quite a bit of clunk/lash when I try to spin the front tires. The majority of the clunk is in the front, middle differential/transmission.
I have determined the following:
The car drives perfectly except the noise
Absolutely silent while stopped
Not related to engine speed
Not directly related to wheel or ground speed
Not related to the transmission gear, it occurs in every gear including while coasting in neutral
Not related to HVAC, it occurs when on and off
Not related to the stereo or audio
Not related to the suspension as far as bumps
The engine fan turns freely when the engine is off
Thoughts?
I'm hoping someone can help me diagnose the problem with my 2015 C300 4matic with 98,000 miles. The tires are fairly new with less than 3000 miles. The front brake pads are good.
I have a light tapping/knocking/fluttering only when the car is moving. The speed can be fast or slow. It is not loud enough to overcome the stereo, but moderately loud outside. I can clearly hear it when driving beside another car with the window down.
I would describe it as an object touching a moving fan. I think it is coming from the front. I can't determine if it is coming from one side or the other.
In steady speed driving, it will speed up and slow down in a seemingly random manner, or even stop. I can sometimes manage to make the noise stop by adjusting the throttle pedal. It happens in acceleration and in deceleration.
My first thought is that it was related to a CV joint or the front drive axle. I jacked up the car and couldn't find anything alarming except, that there seems to be quite a bit of clunk/lash when I try to spin the front tires. The majority of the clunk is in the front, middle differential/transmission.
I have determined the following:
The car drives perfectly except the noise
Absolutely silent while stopped
Not related to engine speed
Not directly related to wheel or ground speed
Not related to the transmission gear, it occurs in every gear including while coasting in neutral
Not related to HVAC, it occurs when on and off
Not related to the stereo or audio
Not related to the suspension as far as bumps
The engine fan turns freely when the engine is off
Thoughts?
Last edited by mcneil141; 07-28-2020 at 10:08 AM.
07-31-2020 | 07:26 PM
#4
Thread Starter
Newbie
Joined: Nov 2010
Posts: 3
Likes: 0
15 C300, 16 Tesla Model S, 2004 Cayenne Turbo
Solution...
I took it to the dealership and they diagnosed it as the driveshaft and coupler coming apart. BTW, it got much worse and went from a light tapping sound to a very pronounced problem. The repair quote is $1775.
Thanks for the help everyone.
Thanks for the help everyone.
