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Whistle noise

Tiny
DOUGLAS DOIG
  • MEMBER
  • 2007 CHEVROLET SUBURBAN
  • 6.0L
  • 2WD
  • 132,000 MILES
A whistle noise at approximately 1200 rpm when accelerating/decelerating. In the past I would clean the MAF sensor and the problem would be gone. So, with the mileage of 132,000, the mag sensor was replaced. No positive results. So, the MAP sensor was next to replace. No positive results. The noise is in the engine compartment and appears to be emanating from the air intake.
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Thursday, March 8th, 2018 AT 6:16 PM

17 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
A spray can of throttle body cleaner.

Clean both sides of your throttle plate.

Return with good news.

Return with friends and family with vehicle problems.

The Medic
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Thursday, March 8th, 2018 AT 6:27 PM
Tiny
DOUGLAS DOIG
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  • 9 POSTS
I neglected to mention, the third item replaced was a throttle body assembly. No positive results. This was done after cleaning the original tba with no positive results.
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Thursday, March 8th, 2018 AT 6:42 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
Reckon it will do it with the air filter removed?

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Thursday, March 8th, 2018 AT 6:46 PM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
Yes, as a matter of fact the noise is worse. As a note, the air filter was replaced with the mass air flow sensor replacement.
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Thursday, March 8th, 2018 AT 6:48 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
Cleaned the interior of the snorkel?

Look for cracks, feel for internal molding imperfections (sand them out).

The Medic
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Thursday, March 8th, 2018 AT 7:12 PM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
No, I have not cleaned the snorkel. I will inspect and clean the snorkel tomorrow. I let will you know the results. Thanks
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Thursday, March 8th, 2018 AT 7:26 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
See you then.

If things are not getting better, I will see if there is another 2CarPro with other ideas.

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Thursday, March 8th, 2018 AT 7:29 PM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
Well, inspected the snorkel with a cleaning too, no cracks or abnormalities. Also, more information: if you head is in the wheel well ( passenger side/air box side), you can really hear it.
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Friday, March 9th, 2018 AT 11:06 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
So strange. Can you make a quick video with your phone of the noise and upload it in your response so we can see whats going on?

With the engine running can you use a pair of needle noise pliers and crimp off the vacuum line going to the brake booster please?

Cheers, Ken
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Friday, March 9th, 2018 AT 12:38 PM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
There is no brake booster and consequently a vacuum line to crimp off. This system has brake lines, running through the back of the master cylinder area. I know what a boost system looks like. I have one on my 1995 Suburban. I am not able to do a video at this time. I would need an extra hand which is not available. The sound is like someone is blowing through a child's whistle. Also, the rpm range has evolved to not only include the original 1200 but also 1500 and 1700. The problem is getting worse. By the way the check engine light has never come on and there are no codes.
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Friday, March 9th, 2018 AT 2:35 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
What about tweaking the MAF one way or another?

Or

Use some painters tape/ etc. That will not easily come loose and tape up sharp edges or the upstream side of the holes in the MAF.

Not trying to cover things up, just trying to disrupt the airflow over it to see if it is the origin of the noise.

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Friday, March 9th, 2018 AT 3:43 PM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
I will give it a shot tomorrow and get back. Thanks
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Friday, March 9th, 2018 AT 3:46 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
Also spray carburetor cleaner around to see if you can make the noise change it sounds like you have a cracked intake manifold.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Friday, March 9th, 2018 AT 6:01 PM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
I like the ideas, especially the air intake manifold.

But, I cannot be two places at once. Producing the noise requires someone in the vehicle to depress the accelerator. In order to apply your suggestions with the noise occurring, a second person would be needed to manipulate the MAF or spray around the air intake for noise changes.

An acquaintance, who is a mechanic, knows a GM tech who has an extensive background with Gen III engines. He is going to consult on Monday.

Also, I have made an appointment with a local Chevrolet dealer for this Wednesday.
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Sunday, March 11th, 2018 AT 12:51 PM
Tiny
KEN L
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Okay great, please let us know what they say I am interested to see what it is. :)
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Monday, March 12th, 2018 AT 11:26 AM
Tiny
DOUGLAS DOIG
  • MEMBER
  • 9 POSTS
Well, turns out that there was indeed a leak in the back of the intake manifold. The leak was found by first checking the fuel trim values for running lean, indication of vacuum leak. It was running lean. Next, a smoke test was performed. The back of intake was the source of the leak. Thanks for all the advice/support.
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Wednesday, March 14th, 2018 AT 9:11 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Nice work, we are here to help, please use 2CarPros anytime.

Cheers, Ken
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Wednesday, March 14th, 2018 AT 12:05 PM

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