Need help diagnosing a knocking sound
Thread Starter
Instructor
Joined: Jul 2012
Posts: 235
Likes: 1
From: Texas
Need help diagnosing a knocking sound
I recently acquired my 2001 C5. The vette is incrediably clean, and garaged most of its life, with only ~72K miles on it. Now it is transitioning to a life of daily driving and not being familar with the vette, I am finding all kinds of little bugs and nuances. Most I have been able to successfully diagnose and resolve from searching around here on CF.com. Thank you CF. This C5 will see its first track this October at Texas World Speedway, so I am trying to make sure the car is mechanically sound and I have one issue that I have not been about to determine the root cause.
There is a knocking sound. I only notice it at lower speeds such as strolling in 1st or 2nd. The knock occurs when there is a release or application of the throttle, as if there is slop in the drivetrain that is knocking. I do not notice it at higher speeds and gears, but it could be present, I just can't hear it. It seems like its the drivetrain, but I did not want to discount something loose or moving around that is creating the knock. In fact I have already identified that one of the mufflers on the aftermarket exhaust was not positioned correctly and is contacting the underside of the heat shield under the truck floor. This is causing a "tinnyer knock" when I drive over a bump, but the other is much more solid sounding with some depth to it. I know a internet forum is not the ideal place for diagnosing car sounds, but with such a knowledge base, I thought you all, I mean ya'll, could help point me in the right direction.
There is a knocking sound. I only notice it at lower speeds such as strolling in 1st or 2nd. The knock occurs when there is a release or application of the throttle, as if there is slop in the drivetrain that is knocking. I do not notice it at higher speeds and gears, but it could be present, I just can't hear it. It seems like its the drivetrain, but I did not want to discount something loose or moving around that is creating the knock. In fact I have already identified that one of the mufflers on the aftermarket exhaust was not positioned correctly and is contacting the underside of the heat shield under the truck floor. This is causing a "tinnyer knock" when I drive over a bump, but the other is much more solid sounding with some depth to it. I know a internet forum is not the ideal place for diagnosing car sounds, but with such a knowledge base, I thought you all, I mean ya'll, could help point me in the right direction.
Last edited by BryanPendleton; Aug 9, 2012 at 02:13 PM.
Tech Contributor
Joined: Jan 2004
Posts: 20,030
Likes: 289
From: Wylie TX --> Less is More, except under the hood !
I had a weird thud sound before and it turned out my battery was sliding around. I had changed it a few months before and it worked its way loose. It was a very deep thud like you describe.
Something easy to check...
Toque
Something easy to check...
Toque
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
I had this happen in 5th and 6th gear only which turned out to be a worn transmission main shaft. At that time, it was a $2700 repair. Not saying its the same thing. You're going to have to isolate the area...specific gears, if all gears, rear-end?
