Squeaking sound on decel
Thread Starter
Drifting
Joined: Mar 2015
Posts: 1,420
Likes: 302
From: CSRA, SC
Squeaking sound on decel
Hi Corvette gurus. I just got my C5 Z06 a week ago and I have a question about a sound I heard for the first time this morning. The car is a 2002 with 50k miles and today while I was coming off the highway on the way to work coasting in gear, there was a squeak from behind the dash/rear of the engine area as the engine RPMs came down. Once I got off the highway I also found that while upshifting the car made the same noise as the RPM came down to meet the next gear. I didn't notice if the squeak was dependent on engine RPM but it only makes the noise while slowing down. Any thoughts? If any other info would help do let me know. Thanks!
Luke
Luke
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Could be a vacuum leak. The vacuum lines connect at the rear of the intake manifold. As you reduce rpms you start to create vacuum. That location also feeds all this under the battery area.
https://www.corvetteforum.com/forums...cuum-line.html
Could also be a belt issue that is fooling you.
https://www.corvetteforum.com/forums...cuum-line.html
Could also be a belt issue that is fooling you.
Thread Starter
Drifting
Joined: Mar 2015
Posts: 1,420
Likes: 302
From: CSRA, SC
I've searched on this and found a handful of people who had similar or identical sounding issues but none of those threads were ever resolved...one person did mention his engine mounts were causing the squeak...
Thread Starter
Drifting
Joined: Mar 2015
Posts: 1,420
Likes: 302
From: CSRA, SC
After some more driving I can describe the sound more thoroughly. Under load it makes a typical exhaust leak air fluttering sound. Under decel/coast it makes a squeaky sound. I think this squeaky sound may be outside air being drawn into the leak as other cylinders on that bank are firing. I'm not 100% confident in this theory but it is slightly backed (I think) by wicked loud gunfire like backfires occasionally happening if I downshift to 3-4k rpm. Normally this would result in some calm popping/crackling, never before full on backfires. So I am thinking its drawing oxygen on decel and providing for a better burn of the unburned fuel entering the exhaust. EDIT: worth mentioning, exhaust is Kooks long tubes, 3" catless x pipe and Corsa extreme axle backs.
I welcome further thoughts on the subject and criticism of my theory as I consider myself far from an expert but smart enough to be dangerous perhaps.
I also had my neighbor rev it up while I stood next to the leak and it was pretty clear where the sound was coming from.
I welcome further thoughts on the subject and criticism of my theory as I consider myself far from an expert but smart enough to be dangerous perhaps.
I also had my neighbor rev it up while I stood next to the leak and it was pretty clear where the sound was coming from.
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