Grinding noise while idle

[RusticSky]

I recently started to hear a metal grinding noise from what I thought was one of the front wheels on my 2008 z71 Tahoe. I first heard the noise while turning at slow speeds so I thought it might be something with the front wheel, but every once in a while I will hear the same noise while idling. I can't seem to pin-point the source because I have not been able to get the noise to duplicate while I'm looking in the engine bay. I did change the serpentine and a/c belt a few months ago, and had the brakes changed, the front driver side needed a whole new caliper. I don't think they are related to the noise, but I don't know what to look for. No change to driving characteristics, but the sound is driving me nuts!

 

[PG01]

Maybe its more of a rattle then a grinding? Check all your heat shields.
Sound clip would help

 

[Kenny D]

How was your idler pulley and belt tensioner? Did they spin freely? I had a pulley explode on my 99 burb and created a mess. Check those to rule them out.

 

[AshleyT]

Following. Please post if you figure it out. My 2004 Yukon XL Denali (AWD) recently started making similar noises after having the transmission replaced. Also had serpentine belt, A/C belt, and alternator replaced at the same time. Noise started about a week or 2 after that service, when turning at slow speeds. Usually the first 1-3 turns out of my driveway then after driving a few minutes it stops. And not every time. Recently we heard it while idling (2-3 times). Can't replicate for our mechanic though. I think he might think I'm crazy.

 

[RusticSky]

I will definitely check the pulley when I get back from my trip. It would make sense after recently replacing it. I will test and report back. I will also try and record the sound.

 

[RusticSky]

So one thing I noticed was that the grinding noise only happens right around 1000rpm. I tested in drive, neutral, and park and can duplicate in all drive states. I recorded the serpentine pully and didn't notice it moving. Very frustrating to pin-point. No engine error code btw.

 

[RusticSky]

Its hard to hear in the video but it happens right after I start accelerating. Around 1000rpm.

 

[Kenny D]

I couldn't hear it through the video, but if you pulled the idler pulley and checked the bearing and the tensioner pulley too, then I am at a loss. Hopefully someone will have a clue and it doesn't turn out to be something expensive.

 

[RusticSky]

I took a better video that you can hear the noise. Listen when I accelerate. It happens about 1000rpm. It will happen while in park also if I hit the accelerator to 1000rpm. I might just need to take it in to get looked at....

 

[DStarr02]

From what i could hear sounds like a heat shield on the exhaust is loose, they will rattle at a resonant frequency, hence the usually at around 1000 rpm. Have someone hit the throttle while you listen under the truck to see it you can figure out which one / where it is, i have seen people replace them, but you can get some plumbing fittings that screw down to hold it tight again for pennies on the dollar. Just use 2 or 3 front to back to hold the entire thing tight.