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Loud vibration noise at 50 mph under dash. 2003 GMC Sonoma.
I have a 2003 GMC Sonoma that suddenly started making a very loud vibration or rattle noise at hwy speeds. I was traveling on a trip and during the trip the noise started. It sounds like it is coming from under the dash towards the hood. It was very windy on the hwy and whenever I could get a certain position next to a semi, I could get the noise to stop momentarily. It stops completely at speeds below 45-50 mph. It sounds like baseball cards on bicycle spokes. I turned off the ac/fan but it made no difference. I looked everywhere for something loose but found nothing.
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Answers
Check the windshield wiper to see if they are being vibrated up and down by the wind while they are parked at the bottom of the glass. I have had that happen. It sounded like something heavier in the dash or the firewall moving.
Then start with the panels on the car that are plastic that covers the front bumper and make sure it's solidly connected to the metal of the fenders. Then do the same for the water splash shield inside the wheel well. Those are held on by push plug plastic snaps. The center pulls out to release them. Make sure those are able to flap around.
Are the raised panels that stand out around the wheels from the metal made of plastic or are they part of the metal fender. If plastic, check that they are solid.
Check the plastic cowl that is behind the hood and below the windshield wipers. That is held down by push clips where the center is pressed in to hold them in place.
2014 Malibu 2LT, 2015 Cruze 2LT,
Sometimes with annoying noises like this, often wind-related, you can experiment with duct tape, by sealing various cracks and crevices, or securing plastic parts that are outside the car. If this is some kind of harmonic vibration caused by a certain specific set of conditions, it could take a while to track this down. It would be nice if you had a second set of ears in the car (and hands) to maybe help locate the general area.
Good points about a second set of ears and hands. Also by noticing where the strong gust of wind coming off the front of a semi tractor is hitting your vehicle at the time that it makes the noise start or makes it worse can help guess where to look for something moving.
Also it could be something like the air dam or air panel that's on the front of many cars under the radiator area to help make the air go to the right places for cooling.
There could be something loose inside the engine compartment.
I've seen body panels moving on cars on the interstate and I've seen the air panels underneath the front that have been damaged on parking blocks on lower vehicles moving and wondered if the drivers can hear those.
If worse comes to worse, you might have someone else drive the car while you travel alongside and around it on all sides to look for something moving while they are telling you by phone that they can hear the problem.
Good luck.
2014 Malibu 2LT, 2015 Cruze 2LT,
Thanks for all the suggestions, I will check them out and let you know. This morning as I drove to work, no noise at 60mph then this afternoon on the way home, the noise returned at 50 mph. Wierd!!
I checked out some of the items suggested and the only thing I could find loose is the front grill. It is plastic and much of the grill is broken where it holds the fins to each other. I put some duct tape on the grill to hold it down and it did not affect the noise. The fender wells are all metal, wipers are good and I ran them while the noise was going on to make sure that was not it. The noise still seems to come from under the dash. Is it possible the front grill would make such a noise that is would resonate inside the cab and under the dash?? Seems unlikely to me but...I guess the next step is to get someone to ride with me and see if they can pinpoint the location of the noise.
You're certainly being analytical about finding this. If it is not something body related it could be an exhaust leak. But you would hear that at other times under certain acceleration loads. That would be accelerator pedal related as well as related to the load on the engine. That might explain why being next to a semi in it's "draft" the load would be less and the leak would quit. I had a doughnut that was between the two parts of the exhaust system where the y-pipe joined to the exhaust pipe start leaking. It was a snapping sound each time a cylinder fired, but very easy to hear with windows down and next to a wall of any kind under acceleration. The doughnut allows the two parts to move relative to each other like a giant o-ring made out of material similar to brake pads.
2014 Malibu 2LT, 2015 Cruze 2LT,
I had someone ride with me tonight and they feel the sound is coming from the drivers side, inside the cab, under the dash. No vibration is felt and the noise begins at speeds around 50 and seems to change in pitch with acceleration. The noise stops below 50 mph. Any ideas from this? Thanks
I might add the noise is not a snapping or popping sound but rather a constant vibration like a moped or something similar. Sorry, not a good description of the sound.
I just thought of something I should add to this post. I had the truck worked on a couple weeks ago. It needed a new water pump and intake manifold gaskets. I drove about 600 miles at hwy speeds after this before the noise began. Did not add this before because did not feel it was related but since you mentioned the exhaust leak it got me to thinking.
So now you're looking for the path of heater hoses, power steering hoses, etc.. Anything that may be moving with the engine and vibrating against the inner fender or firewall when the engine is in certain positions, twisting under load on it's engine mounts.
2014 Malibu 2LT, 2015 Cruze 2LT,
Well, I am 99% sure I solved the mystery of the noise. While I was washing the bugs off my windshield this morning I noticed the molding around the top of my windshield has come unglued and was outside the molding area of the glass and frame. I pushed it back in but decided to go to a glass shop and have them reglue it back in place. He regaled it, taped it up and told me to wait 24 hrs so I will retest the speed factor tomorrow and see if the noise is gone. The glass guy said it could sound like a beetle buzzing around if it was flapping in the wind. It makes sense because the noise was not there in the cool of the morning but back after the afternoon Texas sun heated things up. I will post again tomorrow to confirm but I am betting this is the answer. So, thanks ahead of time for the help. Will update Friday.
I noticed the molding around the top of my windshield has come unglued and was outside the molding area of the glass and frame. I pushed it back in but decided to go to a glass shop and have them reglue it back in place.
Windshield trim had crossed my mind because this was wind sensitive, but I decided there are no longer metal trim pieces and the rubber kind don't cause problems.
Good luck and hope that's the fix!
2014 Malibu 2LT, 2015 Cruze 2LT,
That was indeed the problem. I still cannot believe a piece of rubber can make that much noise. I guess the sound traveled down the glass and made it sound like it was coming from underneath the dash. Really strange. Anyway, got up to 60 mph on the way home tonight and no noise anywhere! Problem fixed. Thanks again for all the suggestions.