Chasing down an engine noise. Please help!
Thread Starter
4th Gear
Joined: Jul 2024
Posts: 4
Likes: 0
Chasing down an engine noise. Please help!
You can hear it upon light revving until about 2500rpm then goes away. Can’t really hear it at idle. And doesn’t happen every rev, and it seems to go away upon a held rev. Literally only when first revving can you hear it. Maybe very early knocking or cam failure?
78k miles, stock with Corsa exhaust. I’ve only owned it a month, but oil looks good, no performance issues or engine lights.
The harmonic balancer is a bit wobbly and I have the summit racing replacement ordered, maybe that’s related? Since it happens only at a rev I can’t pinpoint where it’s coming from, but seems to be the driver side or around the intake manifold or front of the engine.
78k miles, stock with Corsa exhaust. I’ve only owned it a month, but oil looks good, no performance issues or engine lights.
The harmonic balancer is a bit wobbly and I have the summit racing replacement ordered, maybe that’s related? Since it happens only at a rev I can’t pinpoint where it’s coming from, but seems to be the driver side or around the intake manifold or front of the engine.
Le Mans Master
Joined: Jul 2010
Posts: 6,007
Likes: 723
You can hear it upon light revving until about 2500rpm then goes away. Can’t really hear it at idle. And doesn’t happen every rev, and it seems to go away upon a held rev. Literally only when first revving can you hear it. Maybe very early knocking or cam failure?
78k miles, stock with Corsa exhaust. I’ve only owned it a month, but oil looks good, no performance issues or engine lights.
The harmonic balancer is a bit wobbly and I have the summit racing replacement ordered, maybe that’s related? Since it happens only at a rev I can’t pinpoint where it’s coming from, but seems to be the driver side or around the intake manifold or front of the engine.
78k miles, stock with Corsa exhaust. I’ve only owned it a month, but oil looks good, no performance issues or engine lights.
The harmonic balancer is a bit wobbly and I have the summit racing replacement ordered, maybe that’s related? Since it happens only at a rev I can’t pinpoint where it’s coming from, but seems to be the driver side or around the intake manifold or front of the engine.
Thread Starter
4th Gear
Joined: Jul 2024
Posts: 4
Likes: 0
I think you’re into something. The HB is rattling the tensioner like crazy. While I dont think its the tensioner, the vibration may be shaking something else. Can hear it better here.
My summit HB comes in tomorrow so I guess we’ll know middle of the week! Fingers crossed.
My summit HB comes in tomorrow so I guess we’ll know middle of the week! Fingers crossed.
Burning Brakes
Joined: Feb 2019
Posts: 1,028
Likes: 377
From: SW Ohio
To me it sounds like a tensioner or idler pulley. They are relatively cheap for a quality gates or acdelco part, and are wear items. I would replace for sure irrespective of the noise given the age and mileage.
Le Mans Master
Joined: Jul 2010
Posts: 6,007
Likes: 723
I think you’re into something. The HB is rattling the tensioner like crazy. While I dont think its the tensioner, the vibration may be shaking something else. Can hear it better here.
My summit HB comes in tomorrow so I guess we’ll know middle of the week! Fingers crossed.
My summit HB comes in tomorrow so I guess we’ll know middle of the week! Fingers crossed.
Thread Starter
4th Gear
Joined: Jul 2024
Posts: 4
Likes: 0
Good idea, thankfully this is my weekend warrior so I’ll pop the belt off to check things up front. I did replace the idler pulley recently with a c6 one, but it does still shake from the HB being wobbly. I’m feeling better about it being accessory related. I’ve never heard an internal engine noise like this so can’t imagine what it’d be unless it’s really bad like a cam or something I’ve never heard before.
Drifting
Joined: Apr 2018
Posts: 1,323
Likes: 928
From: Burnt Hills NY
Thanks for the feedback. The car had been running about 10 minutes. The sound does not go away after the car has been driven and fully warm. I had the injector tick on my 2014 but this sounds higher pitched and louder to me. This is my first experience with the LT5 engine so it could be normal but my friend's ZR1 does not have this sound.
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Thread Starter
4th Gear
Joined: Jul 2024
Posts: 4
Likes: 0
Not yet, it hasn’t been cool enough to tackle it. I’m hoping next month I’ll finally get to it. I’m starting to think it’s the harmonic balancer banging against the timing cover as opposed to an internal noise, so that’s what I’m going to do first. I replaced the idler pulley and nothing changed but I noticed the HB wobbling quite a bit. I’ve driven it once or twice since then and it still drives fine, full power, no notable issues other than the awful noise. Fingers crossed!
Silver lining is I’m going to install and pin an upgraded HB for an eventual supercharger, so one step closer to that dream coming true.
Silver lining is I’m going to install and pin an upgraded HB for an eventual supercharger, so one step closer to that dream coming true.
Le Mans Master
Joined: Jul 2010
Posts: 6,007
Likes: 723
Not yet, it hasn’t been cool enough to tackle it. I’m hoping next month I’ll finally get to it. I’m starting to think it’s the harmonic balancer banging against the timing cover as opposed to an internal noise, so that’s what I’m going to do first. I replaced the idler pulley and nothing changed but I noticed the HB wobbling quite a bit. I’ve driven it once or twice since then and it still drives fine, full power, no notable issues other than the awful noise. Fingers crossed!
Silver lining is I’m going to install and pin an upgraded HB for an eventual supercharger, so one step closer to that dream coming true.
Silver lining is I’m going to install and pin an upgraded HB for an eventual supercharger, so one step closer to that dream coming true.