Chasing a whistle sound from 2005 6.0

[nsogiba]

Hi all, I'm chasing a mystery whistle sound on my 2005 Suburban 2500 with a 6.0. This is not my video but it sounds exactly like this:

The truck is stock except for a cheap CAI.

I have already done the following and the noise still persists:

Checked intake snorkel for any air leaks at couplers
Removed CAI and ran engine with MAF unplugged
Replaced Intake manifold gaskets as well as valley cover gaskets
Cleaned driver's side valve cover PCV orifice (fixed orifice style) and replace PCV hoses. No blockages or buildup

As you can see in the video the whistle happens at various RPMs and seems to come from different locations, and mostly does it when it's cold out. It sounds like an air leak but I think I've ruled that out. Some folks on the video comments mentioned the A/C tensioner being the cause - I did replace mine a few thousand miles ago wtih a Gates 38159 A/C tensioner. Next steps are to run the engine with the belts off and see if that helps.

Anyone ever seen this before?

 

[Scottydoggs]

take the oil fill cap off see if its gone, if it is, the pcv valve is clogged solid and the noise is the engine actually sucking air in past the front crank seal.

 

[OR VietVet]

Yes, take the oil cap off. I agree with @Scottydoggs. But I am also hearing that screech noise that is likely belt or some pulley bearing related. Once the whistle noise stops, in the video, I can hear the noise I am talking about.

What does it look like under that oil cap and down the oil fill tube?

 

[nsogiba]

Cliffnotes: SOLVED! A/C belt tensioner.

Appreciate the input guys. Since the whistle sounded so much like an air leak, part of my troubleshooting was to remove the intake and do intake manifold gaskets/valley gasket; while I was in there I also did the cam position sensor, oil pressure sending unit, and knock sensors and harness.

I also pulled the PCV hoses and inspected/cleaned them, and pulled the driver's valve cover to clean out any sludge in the drain back holes (there was not much). The motor looks pretty good for 200K miles.













The result? Still whistled. I removed the oil cap with the engine running after a cold start and still whistled. Definitely not a PCV or intake leak at this point.

After doing some homework on Youtube, I saw a lot of guys complaining about their A/C tensioner causing a noise like this. It didn't sound like a belt squeal or bearing noise, and I had replaced the A/C tensioner just a few months ago with a Gates 38159, but at this point I had tried everything else with no results, so I said screw it...

One new GM Genuine tensioner later (PN 12580196, $48 shipped on Amazon) and it's silent again! Hope this helps someone down the road. For what it's worth, the GM part looked identical to the Gates part, except that it didn't have the GM PN stamped on the tensioner arm. We'll see if this one lasts, but for now I'm so happy to have a quiet truck again.

https://www.amazon.com/dp/B00HFLC3HA?ref=ppx_yo2ov_dt_b_fed_asin_title

 

[OR VietVet]

Sorry, I can't help myself....

 

[Fless]

FWIW you have the old style driver's side valve cover; the updated version is better at keeping oil out of the intake. Also, the RTV dam around the knock sensors is supposed to be open at the back, shaped like a "c". Now you have a deeper pool to hold water.

 

[OR VietVet]

FWIW you have the old style driver's side valve cover; the updated version is better at keeping oil out of the intake. Also, the RTV dam around the knock sensors is supposed to be open at the back, shaped like a "c". Now you have a deeper pool to hold water.

You are a bubble buster....LOL