NVH Foam on GMT360s

Dadwagon

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May 21, 2020
141
West coast
My Buick has some NVH (noise vibration harshness) foam that has just started to appear at the back of the rear fender on one side. When I first noticed it, I rather easily was able to take a chunk out, specifically the chunk that was visible from 10 feet away from the vehicle. The foam was weeping from between two body panels at the upper rear of the fender.

Has this auto foam begun to fail on other GMT360 vehicles like mine has? This vehicle was a Texas/Arizona/California vehicle, and I think it was subject to high temperatures during it's first decade of service. Maybe the heat melted it a bit and it's just starting to ooze out now? I couldn't find any mention of this NVH foam via Search function.
 

Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
I've seen it on two of mine, the 02 TB and the 06 Saab. They came out after the quarter panel rusted through at the rear corner of the wheel well. I think it even contributed to the rust by retaining moisture.
 

Reprise

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Has this auto foam begun to fail on other GMT360 vehicles like mine has? This vehicle was a Texas/Arizona/California vehicle, and I think it was subject to high temperatures during it's first decade of service. Maybe the heat melted it a bit and it's just starting to ooze out now? I couldn't find any mention of this NVH foam via Search function.

I'd guess that it's more a question of outright age, and less of 'where' it was originally in service -- especially if you've had the truck awhile. Or, like Moose said... water retention could have been a factor.

BTW... 'everything you've wanted to know about automobile foam'...

 

Dadwagon

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May 21, 2020
141
West coast
Ah, crap. Ok might be some rust doing it's thing in that wheelwell.
Reprise, the link you sent me is what I was reading about before I posed the question. I've never owned a car that had this foam in it...says a lot about the low quality of vehicles I've owned :smile:
 
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Reprise

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Like the article says... 'back in the day', Detroit didn't use foam. Your 80's Camaro (& everything older) had no foam, and there was a lot more NVH, as a result.

As with everything... competition prompts change. So don't be too hard on yourself WRT prior vehicle choices :wink:
 

Mike534x

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Apr 9, 2012
894
That foam was a large reason why the 02-06 Avalanches had such terrible rusting issues with the rear wheel wells. Doing some searching and ending up on an Avalanche forum (while trying to find why rust was such a problem), had people cutting the panel away and found the foam acting as a "sponge" with the amount of moisture that it retained.
 

Reprise

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Interesting, considering their heritage (the full-size pickups, with their already attendant rust issues), and the composite panels they used (which probably hid at least some of the rust, until it was 'too late').

GM should've went to fiberglass outer bed, like they did with the Quadrasteer trucks.
And they had the entire bed that was composite, too, years ago (the take rate was low; theory was b/c it was rated at a lower load rating than the steel bed, plus there was extra cost to get it).
 
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Dadwagon

Original poster
Member
May 21, 2020
141
West coast
My Buick saw two-day snow duty recently with snow chains installed and scratching up that area for a couple miles. This could be where the moisture got in recently and stayed put. What's the harm in scraping away any of this stuff all these years later, it can't be insulating jack or squat??
 

Reprise

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The two potential issues I'd think of would be:

- Increased interior noise level (NBD, if you know it going in, and decide to accept it for the tradeoff of less potential corrosion)

- After removing said foam, the underlying panel might (?) be *more* prone to corrosion, if it's steel, and hasn't had as much / any anti-corrosive applied by the OEM. There are workarounds with this, too, if you can reach the panel.

Would I remove it? Not sure. I can definitely tell you that when I run into this on my own truck, I'll be doing some evaluation -- and if I think it could be retaining moisture -- I'll make a plan to remove it. My Envoy has enough places *without* foam that are susceptible (the big one for me right now, is the liftgate (specifically, the *inside* panel, not the outer one)
 

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