Possessed C5....WTH
Thread Starter
Team Owner
Joined: Dec 1999
Posts: 174,312
Likes: 1,217
From: Here
Pilot of Beer Force 1
Tampa Regional Coordinator
CI 4-5-6-7-8 Veteran
Organizer St. Jude Fundraiser
I believe in the Beer Fairy
Possessed C5....WTH
OK....here's the deal. 2002 C5 and the past few months when driving and for a few hours afterwards we get a loud popping/thumping sound coming from the car 
Nothing has changed, no new mods etc. When driving it sounds like it is coming from the tunnel below the shifter or from behind the dash. It sounds like something is smacking the bottom of the car. Come home and park in the garage and it will do this periodically for several hours. It is random and there is nothing loose under the car that could cause this. We had it on the lift last week and everyone in the shop heard it but no ideas where it is coming from.
Thoughts? suggestions? dumb answers?
see video added in post #41
Nothing has changed, no new mods etc. When driving it sounds like it is coming from the tunnel below the shifter or from behind the dash. It sounds like something is smacking the bottom of the car. Come home and park in the garage and it will do this periodically for several hours. It is random and there is nothing loose under the car that could cause this. We had it on the lift last week and everyone in the shop heard it but no ideas where it is coming from. Thoughts? suggestions? dumb answers?
see video added in post #41
Last edited by pewter99; Jan 22, 2014 at 09:48 AM.
Thread Starter
Team Owner
Joined: Dec 1999
Posts: 174,312
Likes: 1,217
From: Here
Pilot of Beer Force 1
Tampa Regional Coordinator
CI 4-5-6-7-8 Veteran
Organizer St. Jude Fundraiser
I believe in the Beer Fairy
Thread Starter
Team Owner
Joined: Dec 1999
Posts: 174,312
Likes: 1,217
From: Here
Pilot of Beer Force 1
Tampa Regional Coordinator
CI 4-5-6-7-8 Veteran
Organizer St. Jude Fundraiser
I believe in the Beer Fairy
no...thats the first thing everyone thinks...this is different besides if that was the case it would stop pretty quickly after it warmed up or for sure long before a few hours after being parked...I have had the car home now for 3 hours and it just made the noise again 5 minutes ago 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Team Owner
Joined: Dec 1999
Posts: 174,312
Likes: 1,217
From: Here
Pilot of Beer Force 1
Tampa Regional Coordinator
CI 4-5-6-7-8 Veteran
Organizer St. Jude Fundraiser
I believe in the Beer Fairy
yeah and I don't know any priests to do an exorcism
hmmm
of course if thats it then we get to play the WTF is it game
Thread Starter
Team Owner
Joined: Dec 1999
Posts: 174,312
Likes: 1,217
From: Here
Pilot of Beer Force 1
Tampa Regional Coordinator
CI 4-5-6-7-8 Veteran
Organizer St. Jude Fundraiser
I believe in the Beer Fairy
Le Mans Master
Joined: Apr 2012
Posts: 7,796
Likes: 2,256
From: Brighton MI
Based on your description, I suspect a vacuum is being pulled somewhere where it should not be and my first guess would be the gas tank. Next time you park it after driving it awhile, take the gas cap off and see what happens. Next guess would be cooling system, but this is far less likely given the sounds you are hearing.
If nothing there, I would suspect the noise is coming from something contracting as it cools (exhaust, etc.) and it is out of position vs. where it should be and does not have the freedom of movement it should have. This is obviously a hunting mission at this point. Don't overlook a broken motor mount as a possible cause.
Good luck - let us know what you find!
If nothing there, I would suspect the noise is coming from something contracting as it cools (exhaust, etc.) and it is out of position vs. where it should be and does not have the freedom of movement it should have. This is obviously a hunting mission at this point. Don't overlook a broken motor mount as a possible cause.
Good luck - let us know what you find!
Last edited by 4XLR8N; Jan 21, 2014 at 03:01 PM.
Melting Slicks
Joined: Sep 2007
Posts: 2,182
Likes: 473
From: Rockland County NY
2020 C5 of the Year Finalist - Modified
2016 C5 of the Year Finalist
St. Jude Donor '12, '14
I had something similar happen with my sport seats. The carpet got wet and shorted the passenger's side electronics and the motor kept making adjustments long after the car was off until the battery died. I solved the problem by fitting racing seats haha. Good luck!
Drifting
Joined: Oct 2011
Posts: 1,872
Likes: 333
From: Olmsted Falls Ohio
St. Jude Donor '12 thru '24
Seeing that appears to come from under the car, can you get it up on a lift or otherwise get under it and try to narrow down the area the sound is coming from? Even putting it up on jack stands and laying under the car for a few minutes may tell you more about where it eminates from.