Need help diagnosing a fluttering noise on acceleration

[bjhayes]

I've started hearing a 'fluttering' sound on acceleration but only when my engine is cold. After 10 or so minutes of driving the sound is not there anymore. Dealer kept the car overnight but of course everything is normal sounds to them so it's up to me to narrow down the culprit and I need some suggestions.

The best way I can describe it is a muffled sound of a card in a bike spoke (very different from a tick). Noticeable in the cabin if the radio is turned down. Very noticeable as I drive by walls, other cars and it bounces off.

I first noticed it within a week or so after dealer replaced my leaking oil pan gasket. Maybe coincidence but also wondering if the oil pan removal procedure has anything where they unbolt any part of the exhaust? Possible exhaust leak?

Oil life and levels are good.
Car is a 2009.1 w/ 64k miles, is my daily driver, and is all stock except for the Rotofab intake.
I do not notice any difference in how it drives.. seems to have same power, response, etc...

Any ideas?

I am the original owner and still have till Feb 2015 on my GMPP extended warranty so any input I can get to narrow this down to something that should be covered and I can get the dealer to recognize is much appreciated. Even if it turns out to be something not covered I'm fine with that too just need to get this taken care of.

[Chewy]

Probably piston slap. It's common with the L76 and only happens when cold.

[bjhayes]

Probably piston slap. It's common with the L76 and only happens when cold.

hmmm.. Could be.. but I've never noticed it before and I quickly notice any difference in sound or feel with my car. If it is piston slap why would it all of a sudden start doing this after 5 years.

[Chewy]

Time doesn't have as much to do with it as use. My GT did it, but it went away pretty quickly. I'm not saying that's it, but it sounds like what you're experiencing. It could be that it's just getting worse and more noticeable.

Chris

[I12XLR8]

Is piston slap ever covered under warranty? I'm bringing mine in for what I think is a slap problem as well


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[bjhayes]

Ok... This morning I only noticed it when in gear. In neutral or park I can not hear it... But put it in drive and start accelerating I can. I found a post on a a GMC truck board that describes exactly what I'm experiencing but no one there has responded yet and I'm going to watch that thread too. (http://www.silveradosierra.com/uncategorized/flutter-ticking-noise-on-acceleration-t222722.html).

This all started after the oil pan gasket was replaced. I'm wondering what is involved in that procedure to possibly cause this. Exhaust leak? Motor mount?

[bjhayes]

Ok... This morning I only noticed it when in gear. In neutral or park I can not hear it... But put it in drive and start accelerating I can. I found a post on a a GMC truck board that describes exactly what I'm experiencing but no one there has responded yet and I'm going to watch that thread too. (http://www.silveradosierra.com/uncategorized/flutter-ticking-noise-on-acceleration-t222722.html).

This all started after the oil pan gasket was replaced. I'm wondering what is involved in that procedure to possibly cause this. Exhaust leak? Motor mount?

[G8 GT V8]

I wonder if it is something loose in your exhaust and while the engine is under load, in gear, it's torque twisting just enough to have an issue. It would be worth asking the shop if they loosened your exhaust when changing the gasket. Or, if you're mechanically inclined, you could crawl under to see if you find anything loose.

[bjhayes]

I wonder if it is something loose in your exhaust and while the engine is under load, in gear, it's torque twisting just enough to have an issue. It would be worth asking the shop if they loosened your exhaust when changing the gasket. Or, if you're mechanically inclined, you could crawl under to see if you find anything loose.

Shop was GM dealership that replaced the gasket under warranty. They have done work on the car since new and I have not had any real problems with them. When I ask them about the noise afterwards they say they don't hear anything that is not normal.

Does the GM gasket replacement procedure require any unbolting of exhaust?

Being mechanically inclined is not a problem... My biggest problem is having the time to get to it and the limited space I have to work on it.

Went out again today at lunch (cold start with air temp in the low 70s) and was able to confirm I only hear it in gear while accelerating. As I started to hear it I shifted up to neutral and gave some light throttle and sound is not there anymore (or so slight I can't hear it)... then I shifted back to drive and gave some light throttle and there it is again. After 10 or so minutes of driving it's no longer notiecable at all.

It may be piston slap but seems odd it would only be noticeable when in gear under load. Makes me think something in the exhaust leak side... but who knows.

[Chewy]

I only heard the piston slap on my GT when under a load. I always made sure to take it easy until up to running temp.

[roman1978]

I think I might be having the same issue but under deceleration at low speeds like around 20 miles

[bjhayes]

I only heard the piston slap on my GT when under a load. I always made sure to take it easy until up to running temp.
Thanks... While I am not new to V8 engines this is the first aluminum block I've had and the first time I've had to deal with such noticeable noises from an engine.

[Seattle09GT]

The L76 makes a lot of...noises.

[GM Customer Service]

I've started hearing a 'fluttering' sound on acceleration but only when my engine is cold. After 10 or so minutes of driving the sound is not there anymore. Dealer kept the car overnight but of course everything is normal sounds to them so it's up to me to narrow down the culprit and I need some suggestions.

The best way I can describe it is a muffled sound of a card in a bike spoke (very different from a tick). Noticeable in the cabin if the radio is turned down. Very noticeable as I drive by walls, other cars and it bounces off.

I first noticed it within a week or so after dealer replaced my leaking oil pan gasket. Maybe coincidence but also wondering if the oil pan removal procedure has anything where they unbolt any part of the exhaust? Possible exhaust leak?

Oil life and levels are good.
Car is a 2009.1 w/ 64k miles, is my daily driver, and is all stock except for the Rotofab intake.
I do not notice any difference in how it drives.. seems to have same power, response, etc...

Any ideas?

I am the original owner and still have till Feb 2015 on my GMPP extended warranty so any input I can get to narrow this down to something that should be covered and I can get the dealer to recognize is much appreciated. Even if it turns out to be something not covered I'm fine with that too just need to get this taken care of.

Hey bjhayes,

We're hoping that some of the forum members can help with narrowing down the cause of this fluttering noise. We can understand how this sound can become annoying and apologize that the dealership wasn't able to resolve this when it was in for service. If you'd like for us to document this within our system for future reference, or would like for us to look into anything for you we're more than glad to do so. Just send us a private message with your full contact information, VIN and dealership name if interested.

Amber N.
GM Customer Care

[bjhayes]

Hey bjhayes,

We're hoping that some of the forum members can help with narrowing down the cause of this fluttering noise. We can understand how this sound can become annoying and apologize that the dealership wasn't able to resolve this when it was in for service. If you'd like for us to document this within our system for future reference, or would like for us to look into anything for you we're more than glad to do so. Just send us a private message with your full contact information, VIN and dealership name if interested.

Amber N.
GM Customer Care

It's been a couple of months now and the fluttering seems to be getting worse and just yesterday morning had another issue of loud ticking for several minutes. Of course this never happens when I take it in for service. Summer temps are here (regularly in the 90s) and it still takes over 10 mins for this fluttering to quiet down. I will send you a PM with the info requested and we'll see if there's anything you can actually help me get figured out on this. I'm at my wits end on this thing. I am preparing to factory order a 2015 C7 later this summer but I don't want to do that until I have this issue figured out. I love this car but am getting very frustrated with these noises and lack of confidence in my dealer to resolve.

[TOOBLUE]

Sure sounds like a exhaust leak to me.. Roger

[bjhayes]

Sure sounds like a exhaust leak to me.. Roger

The ticking is definitely not exhaust leak. Played a video of it for dealer and he also thinks lifters but since it never does it for them they will not do anything. The flutter could very well be exhaust leak. It did not start till the dealer replaced my oil pan gasket... Which procedure says to slightly lift the engine for clearance...

[GM Customer Service]

It's been a couple of months now and the fluttering seems to be getting worse and just yesterday morning had another issue of loud ticking for several minutes. Of course this never happens when I take it in for service. Summer temps are here (regularly in the 90s) and it still takes over 10 mins for this fluttering to quiet down. I will send you a PM with the info requested and we'll see if there's anything you can actually help me get figured out on this. I'm at my wits end on this thing. I am preparing to factory order a 2015 C7 later this summer but I don't want to do that until I have this issue figured out. I love this car but am getting very frustrated with these noises and lack of confidence in my dealer to resolve.

Hi Bart,

I understand you are frustrated due to the noises you have been noticing with your vehicle and apologize for the inconvenience. I wanted to let you know we received your private message and will continue our interactions there.

Laura M.
GM Customer Care

[miamio96]

Was the flutter sound ever solved? Mine just developed the same thing this past week. Nothing at idle, but it is there under acceleration.
thx