Surely this is going to afflict someone else, so after two years of many attempts to find it I thought I'd share. Around 2900 RPM I've had this horrible dash buzzing/rattle...sounds like something wants to come apart somewhere in the center-ish of the dash. If it were at a high RPM that would be one thing, but this is right in the middle of the useful powerband, particularly for climbing hills. I've poked around with an auto stethoscope, driven down the highway at constant throttle in third gear with the center console disassembled and foamed everything to no avail. Tried the power valve fix. The truck wouldn't make the noise in neutral (only in drive while rolling) which made searching for it really hard.
But yesterday it started making the noise out of gear, which changed the game!
So, finally...here it is. There are two cables coming off the forward end of the shifter assembly. The one on the left goes to a switch for the shift button on the shifter. The one on the right appears to be a housed mechanical cable for the shifter (not that it really matters what it is for this).
The one on the right crosses the one on the left underneath the plastic air intake vents at the bottom of the air mixer assembly. (They run under the front seats for recirculated air...not that that matters either.) 2900 RPM is apparently the natural frequency for the engine/transmission/shifter combination, and these cables transmit the vibration from it pretty readily.
I fixed it by stuffing 3/4" neoprene foam in between them, and then wrapping a big square around the one on the right since it seemed to be the worse offender. Didn't want it vibrating against the air vents or cabin floor after I buttoned everything back up. Just took it up and down the highway and can't make the noise come back, so this must have been it.
So if you have a seriously annoying low frequency, low pitch rattle around 2900 RPM...this might be it! And really judging by the design I'd be surprised if more people don't get it eventually...
Fixed my dash rattle!
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SilverGhost
- Posts: 321
- Joined: Wed Jan 10, 2007 6:23 am
- Location: Houston, TX
I do...they're not very good and I have lots of foam already holding other wires and cables in place from previous attempts to fix this, but they should give an idea of where the cables are.
Here's everything opened up. You actually can't see the cables here yet.
Here you can see the offending cable up close:
Can't really show how I fixed it very well. They were touching and vibrating just under the plastic air intake assembly, so I shoved a couple pieces of foam between and around them there. So far, so good.
Oh, one more thing, I think what changed the noise to happening while the truck is in neutral was something I did to the left cable the day before. It runs sort of up the firewall behind the cooler/heater assembly and then up into the dash, but very loosely. There's actually foam attached to the mixer door in the driver's footwell to prevent it from rubbing. I ziptied it to a hole in the cooler/heater, which probably held it in place differently so it would make the noise in neutral.
Fun times looking for noises in this thing...
Hopefully I'm done for a while though, I'd like to turn around and finish up my sound damping and insulation project:
Damping and foam in the front fenders was a huge improvement and significantly reduced the booming noises from the front wheels. I'd like to get into the rear quarter panels and wheel wells if I get time this weekend...
Here's everything opened up. You actually can't see the cables here yet.
Here you can see the offending cable up close:
Can't really show how I fixed it very well. They were touching and vibrating just under the plastic air intake assembly, so I shoved a couple pieces of foam between and around them there. So far, so good.
Oh, one more thing, I think what changed the noise to happening while the truck is in neutral was something I did to the left cable the day before. It runs sort of up the firewall behind the cooler/heater assembly and then up into the dash, but very loosely. There's actually foam attached to the mixer door in the driver's footwell to prevent it from rubbing. I ziptied it to a hole in the cooler/heater, which probably held it in place differently so it would make the noise in neutral.
Fun times looking for noises in this thing...
Hopefully I'm done for a while though, I'd like to turn around and finish up my sound damping and insulation project:Damping and foam in the front fenders was a huge improvement and significantly reduced the booming noises from the front wheels. I'd like to get into the rear quarter panels and wheel wells if I get time this weekend...
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