Vibration noise under dash at speeds above 50 mph

NKPLTRR

MEMBER
2003 GMC SONOMA
4.6L
6 CYL
2WD
AUTOMATIC
104,000 MILES

My GMC has developed a very strange and loud noise at speeds above 50 mph. The best way to describe it is sounds like baseball cards on bicycle spokes or a noisy moped. The noise is coming from the drivers side under the dash but there is no vibrations. The noise seems to change pitch as you speed up and slow down but maintains a constant noise when driving at speeds above 50. Just had the truck worked on last week installing a new water pumps and intake manifold gaskets. Could I have a leak there?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Are you sure the sound is under the dash on the driver's side? There really isn't anything there that would cause that. The fan motor under the dash on the passenger side could make noise.

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Wednesday, September 3rd, 2014 AT 8:20 PM

NKPLTRR

MEMBER
2 POSTS

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 reglued it and 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.