2500HD Sunroof Howl at Highway Speeds

jasonvp · July 5, 2016

Heya folks -

My dealership and I are currently trying to troubleshoot a new annoyance with my 2015 2500HD: a massive howl coming from the leading edge of the sunroof at highway (~60MPH or higher) speeds. Here's the history:

I haven't actuated the sunroof in, perhaps a year or so. A few weekends ago, I parked the truck outdoors on a reasonably sunny, warm day. To keep the interior cool, I cracked the sunroof open with the "Vent" button. All good. When I started the truck back up, I closed the vent and drove home. It was during the drive home that the howl started. Right around 60MPH or higher, the noise is so awful I almost need to wear ear plugs. It's not a wind noise whistle that you may be used to hearing. It's quite a bit louder than that.

I've noticed that it seems to behave first thing in the morning; perhaps that's a temperature thing. When I drive to work in the morning, I don't hear it. But any time after that, *HOWWWWWWL*. Fortunately(?) I see no evidence of water making its way past the seal. Also, I can make the howl go away by slightly opening the sunroof, so I know it's definitely that.

The dealer has tried:

Dielectric grease
Adjusting the sunroof
Performing a TSB that calls for replacing the glass's weatherstripping

None of these has helped. Before I drive the truck back, are there any other ideas or suggestions?

Thanks!

dab5577 · July 7, 2016

Do you have clearance markers on the roof? I have a howl from the center roof marker on mine that I still need to get them to fix. Doesn't happen all the time.

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jasonvp · July 8, 2016

Do you have clearance markers on the roof? I have a howl from the center roof marker on mine that I still need to get them to fix. Doesn't happen all the time.

Yep, I do have the running lamps/clearance markers. And I suspected them, as well. But it clearly goes away when I crack the sunroof open a bit.

dab5577 · July 8, 2016

I don't doubt it's the sunroof, but if you want to try .... Put a piece of painters tape over the front edge of the base of the center marker and see if it goes away. That's how I found my howl.

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jasonvp · July 8, 2016

I don't doubt it's the sunroof, but if you want to try .... Put a piece of painters tape over the front edge of the base of the center marker and see if it goes away. That's how I found my howl.

If you get the opportunity, could you snap a quick pic of that so that I can see? There's no real "edge" of the center marker, per se. It protrudes up through the roof. Did you just cover the seam between the light and the roof?

dab5577 · July 8, 2016

Yeah - sorry if that was confusing. I just covered up the seam between the bottom of the center light and the top of the roof with a piece of painters tape.

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KMGZ400 · July 8, 2016

my sunroof had a whistle and i rubbed silicone spray into the rubber gasket around the glass and it stopped

jasonvp · July 14, 2016

Yeah - sorry if that was confusing. I just covered up the seam between the bottom of the center light and the top of the roof with a piece of painters tape.

I'm going to tentatively say: dammmmn. This seems to have (knock on wood) solved it. I guess the tape is interrupting the aero flow over the middle light just enough that it's not slamming down into the leading edge of the sunroof or something like that.

Thanks for the suggestion!

dab5577 · July 14, 2016

I haven't been able to spend time with the shop to get a permanent fix....I just put a piece in when it annoys me and pull it off when I'm done with a trip. Let me know if you get any permanent resolution. I plan to just pay them to put a new center marker on cause I don't have time to deal with a science experiment to warranty fix it. Tapes an easy fix, but seems lame on a $60k truck.

Glad it seems to have worked.

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dab5577 · August 15, 2016

So...didn't have the time to work with the dealer for the howl noise to occur when they test drove it so I just paid them to replace the center clearance light. Well, now the damn thing seems to do it more frequently. Any ideas? I know it has to be the center light. I really don't want to bandaid fix it. Here's a video of what it's like I took a year ago....https://vimeo.com/178950574

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20SierraL8T24 · August 16, 2016

So...didn't have the time to work with the dealer for the howl noise to occur when they test drove it so I just paid them to replace the center clearance light. Well, now the damn thing seems to do it more frequently. Any ideas? I know it has to be the center light. I really don't want to bandaid fix it. Here's a video of what it's like I took a year ago....https://vimeo.com/178950574

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I don't have the lights up top and thankfully I don't have that noise.

Palazzoblues · September 6, 2016

My 1500 High Country Did the exact same thing. Problem was fixed by trading up to an 2500HD LTZ Duramax with NO sunroof!

Shagmax · October 27, 2016

Thats ridiculously loud... They should fix that for as expensive as these are...

redwngr · October 27, 2016

I wonder if you can reduce (or change) the amount of noise by changing the tightening sequence for the centre light or by pushing it ahead or back or to one side while tightening.

Stands to reason that if they don't all do it, something must be different.