Air Tunnel Soundproofing

[Pinz710m2]

I know there were a lot of posts asking about this. So here it is:

This is mostly and arts/crafts project, quickie how-to:

Remove the old rotten insulation (as was the case with mine)
or scrape off the paper/backing if that's all that is left of the old
soundproofing. The original adhesive was freakin' strong, so
this took some good solvent and a lot of scraping with a paint
scraper.

Once the entire tunnel is clean and oil free, I would advise a
quick coat of paint. It only took me about 30 minutes to mask
off the tunnel and using some rattle can rustoleum engine paint
I cleaned up the surfaces and painted them black.

Once everything is dry, use paper and tape to create a template
of the interior space. Transfer the template to 1/2" thick Dynamat.
The Dynamat is almost identical to the material I scraped out of
the tunnel. BEFORE you apply the Dynamat, I would give it a
spray of waterproofing. I was stupid and did it after the fact.

Apply the top first, then the bottom, and be sure to use the tabs
provided. They will keep the wind from ripping the insulation
off and pushing it into the fan. (That would be a bad day) After
you apply the bottom and top, measure, cut, and apply the sides.
With this configuration the sides help seal the top in place.

Roll everything and be sure that the adhesive is solid and that
there are no air bubbles or places that the adhesive did not seal.

Done. This made a huge difference in the sound level in the cab.

PICTURES:

Top installed


This is the bottom prior to installation


Bottom and top installed


Done!

[audiocontr]

Would this trap water and promote rust?

[TechMOGogy]

Would this trap water and promote rust?

It is actually Dynaliner which is oil and water resistant plus he sprayed it with waterproofing.
I would bet it would hold a lot less water than the old insulation
You could POR15 the inside of the tunnel and then add dynaliner and your good to go

http://www.dynamat.com/brands/dynaliner/

[Pinz710m2]

It shouldn't. Look inside your own. This is a stock "upgrade". And
I say upgrade only because the old stuff was 42 years rotten. This
is what the OEM had there for the past 42 years and I had no rust
at all. Just to be sure, I added the waterproof coating mentioned
above.

[David Dunn]

The last Pinzgauers did not have matting on the bottom of the tunnel, just the sides and top.

[Pinz710m2]

If there aren't any tabs on the bottom, I'd probably use
a couple washers and sheet metal screws to secure the
soundproofing, just to be sure it doesn't come off with the
wind and get tangled in the fan.

[David Dunn]

Sound deadening isn’t required on the bottom of the tunnel, it isn’t in the passenger compartment, like the sides/top. And without the insulation for moisture to get trapped behind, it is suck through the tunnel

[McCall Pinz]

Good reminder...I've never gotten back around to re-installing this stuff- 1/2" thick dynaliner... got it.

[eToothpaste]

I just ran across this looking for sound blocking ideas and noticed that Dyna- brand does not describe dynaliner as having any kind of sound dampening properties. It is used on top of dynamat to provide thermal insulation (though it probably does provide some sound insulation).

On second look on a different page they call it a thermoacoustic liner as it helps block lower frequency sound in combination with dynamat.


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[krick3tt]

I removed the 'insulation' in the tunnel several years ago and never reinstalled anything. I notice no appreciable sound difference with or without it. The stuff I removed was very deteriorated and just crumbled in my hand except for the layer attached to the metal. It held water and was not (to me) a good idea to keep it there.
Perhaps the 'no appreciable difference' was in effect due to the deteriorated condition of the stuff I removed which probably was not doing a proper job.
I have installed other type of sound deadening materials to other metal surfaces and it has made a difference.

[idstitch]

Has anyone tried a product called FatMat? Comes in 50 and 80 mil thickness and is supposed to tolerate hot areas and kill sound.

[rollingpinz]

Hello

So I’ve been reading the air tunnel posts because I like the idea of a quieter ride, but the constant warning of water being trapped underneath (no matter what type is used) had me concerned about my truck. It seems rust is my main issue. There has been some patch work done by a previous owner. Not great work, but passable. My son has done some seam repairs on it. Again, not great, but passable. He did just get his merit badge in welding so I know there’s going to be improvement.
Anyway, I started scraping off the material on the sides. The middle had pulled away from the metal and made most of the material easy to remove. I saw that the bottom looked to be the same so I pushed on it and … the horror, the horror. There’s a rust hole that runs most of the length of the air tunnel. I placed my drop light over it and looked in the passenger foot well. Yep. I saw the light.
It seems like it could be patched and because of the location, passable will be ok. It’s just going to be a pain to work in such a small space.
The moral of the story is to get that stuff out of there and think twice before you put anything on a horizontal surface. Noise is better than rust.