Chasing a whistle sound from 2005 6.0 - SOLVED

[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

 

[Bigburb3500]

And here I was going to tell you to look for the super charger… guess that wasn’t the right whistle.

 

[strutaeng]

I'm glad you figured it out. I'll watch the video later and try to store in my mind...you know to add to my diagnostics knowledge.

My wife's 3.6 Pentastar Chrysler minivan was making this horrendous squealing noise. I figured it was a tensioner. I jacked it up and listened with HF stethoscope, but that wasn't it. I noticed the harmonic balancer wobbling like crazy and that's where the squealing was seemingly coming, but I couldn't put the probe on it because it's spinning. I watched a few YT videos and yep, the metal halfs separate and wobbles on the pulley. Kinda crazy. $175 for a Mopar harmonic balancer replacement. They seem to last 90-100k. SMH.

OTOH, on an 6.0 LS I'm building I found a used harmonic balancer from a guy on FBMP last year...for a whopping $20. Probably good for 500k if I had to guess?

 

[Fless]

You are a bubble buster....LOL

I identify as a party-pooper.

 

[nsogiba]

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.

What's the difference between the old and new style valve cover? My truck has the fixed orifice (no check valve) and consumes zero oil.

As for the RTV Dam...this is my 8th LS motor doing it that way and I've never had an issue. YMMV

 

[Fless]

No problem; I like to go by the TSB: https://www.tsbsearch.com/Chevrolet/02-06-04-023A

 

[Fless]

What's the difference between the old and new style valve cover? My truck has the fixed orifice (no check valve) and consumes zero oil.

As for the RTV Dam...this is my 8th LS motor doing it that way and I've never had an issue. YMMV

@donjetman's show & tell: https://www.tahoeyukonforum.com/threads/drivers-side-valve-cover-solved.152022/post-1934792

 

[nsogiba]

Welp...I spoke too soon. The new tensioner still occasionally whistles, just at a different RPM and frequency. It looks identical to the Gates unit. Is there an improved version or redesign for this thing?

 

[RTCburb]

I am chasing the exact same whistle in my '07 Suburban 2500 with 6.0.

Got so frustrated I asked a local shop that I respect to try and chase it down. Talked to him earlier today and they are stumped. No joy.

Please keep us posted and if I figure anything out, I'll report back here.

 

[Just Fishing]

Can't you do what they did to the later Tahoes?
They deleted the AC belt tensioner in favor of a stretch fit belt.

This one comes with the tool and everything.
The instructions for the tool suck, but the included tool works great for both removal and installation.

"ACDelco GM Original Equipment 19210691 Air Conditioning Compressor Belt Kit with Tool"

Amazon.com

 

[petethepug]

On high milage motors it’s not uncommon to have a worn pulley along with the belt. After 200k+ miles on our 90 (supercharged, LOL) VW Corrado, the power steering pulley wore out of spec.

The VW, like these GM V8 motors, the belt & pulley are at the front of the motor, down low and susceptible to road contamination and water.

Replacement of both the belt and the pulley permanently stopped the squealing / squeak.

 

[RTCburb]

Maybe solved.

On top of the whistling sound, I also had a hard starting issue. Only occurred after the engine was at operating temp and only if restarted within roughly 5-30 minutes. (like after running in to a store).

Cleaning the injectors seems to have solved both problems.

 

[West 1]

Just read this post today and realize that I had installed a Gates Tensioner last Nov or Dec. Have an odd whistle also. Only happens once in a while, not consistent. I guess I will need to swap out that tensioner also. Thanks for the information share.