Rattle when accelerating
Thread Starter
Cruising
Joined: Sep 2017
Posts: 11
Likes: 1
From: Ellicott City
Rattle when accelerating
I have noticed a rattle noise when I am doing 35-40 mph.. then gently accelerate. It does not do it when I rapidly accelerate, just while sustaining low speeds and depressing gas pedal slightly. Disappears at about 55 +. Thoughts..advice?
Melting Slicks
Joined: Aug 2014
Posts: 2,587
Likes: 873
I had a small trim panel misalignment near the rear passenger speaker causing me a slight rattle on acceleration. You'll need to determine if its from inside the cabin or from the drivetrain as there are several bulletins relating to rattle from the driveshaft.
https://www.tsbsearch.com/Chevrolet/18-NA-268
https://www.corvetteactioncenter.com...2020-1480.html
https://www.tsbsearch.com/Chevrolet/18-NA-268
https://www.corvetteactioncenter.com...2020-1480.html
Last edited by SladeX; Sep 15, 2021 at 10:08 AM.
Racer
Joined: Aug 2019
Posts: 436
Likes: 239
From: Las Vegas
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Instructor
Joined: Jun 2020
Posts: 223
Likes: 166
From: Greensburg, PA
Have you changed out anything on the exhaust? When I had my X-pipe put on, one of the connectors came loose and it had a weird, rattle type sound only on soft acceleration as you are saying. That ended up being my culprit and I just had to tighten up the bolt.
Racer
Joined: Feb 2020
Posts: 305
Likes: 245
From: GSO, NC
Hi Scott,
Is your car an Automatic? If so, put it in to manual mode and drive at the same speed range and see of you get the same rattle. My GS (which is an auto) does something similar. To me it sounds like a small metal flap vibrating and rattling against another metal part. This shows up when gear is in Auto and Touring mode when the car goes in to V4, goes away when it goes to V8 mode. I now drive 99.99% on manual mode so I don't get the chance to hear it any more, but if I go in auto, I will hear it from time to time when the speed and amount of acceleration is not sufficient to make it not go to V8. I was very concerned at first, since this is my first Corvette and first GM V8. I did read here on a thread (sorry I cannot find it easily) that the sound is coming from one or more of the valves in the exhaust, when they are partially or fully closed. Since the sound was not coming from the engine, I have been keeping my fingers crossed, and hoping it is just the valve rattling.
Also try setting the sound to full track mode, this open the exhaust valves, then see if you are still getting the sound. It is raining a little here today, if not I would have checked it out for you.
Best regards,
Vip.
Is your car an Automatic? If so, put it in to manual mode and drive at the same speed range and see of you get the same rattle. My GS (which is an auto) does something similar. To me it sounds like a small metal flap vibrating and rattling against another metal part. This shows up when gear is in Auto and Touring mode when the car goes in to V4, goes away when it goes to V8 mode. I now drive 99.99% on manual mode so I don't get the chance to hear it any more, but if I go in auto, I will hear it from time to time when the speed and amount of acceleration is not sufficient to make it not go to V8. I was very concerned at first, since this is my first Corvette and first GM V8. I did read here on a thread (sorry I cannot find it easily) that the sound is coming from one or more of the valves in the exhaust, when they are partially or fully closed. Since the sound was not coming from the engine, I have been keeping my fingers crossed, and hoping it is just the valve rattling.
Also try setting the sound to full track mode, this open the exhaust valves, then see if you are still getting the sound. It is raining a little here today, if not I would have checked it out for you.
Best regards,
Vip.
Thread Starter
Cruising
Joined: Sep 2017
Posts: 11
Likes: 1
From: Ellicott City
VIP.. Thank you for the detail of your explanation. I took it back to the dealer and have it scheduled for diagnoses & possible surgery 9/28. I will do what you have advised today and ck it out. I wanted to add cutouts to it but the dealer told me they may have to cut through the existing exhaust system if its a drive train issue. So I am holding off on them for now.
Instructor
Joined: Sep 2020
Posts: 143
Likes: 75
From: Tolland, Connecticut
Please keep us posted. I have the same problem with my 2015 M7 NPP right at 1500 rpm. Worse when it gets good and hot and my best guess at this time is a loose baffle inside the muffler. Been fussing with this since I bought the car. year ago and nothing obvious after looking for loose hangers, banging on the mufflers and trying every conceivable combination of exhaust setting and gear.
