I’ve always thought that 3rd gen 4Runners were heavy on road noise, even when they were brand new. I certainly feel that way about my newly-acquired 21 year old model. So before I go swapping out that factory cassette player and dealer-installed accessory in-dash CD, I thought I’d see about improving things in the cabin a bit.

What I immediately found is holy shit, Dynamat is expensive! You would have a small fortune lining your ride in that stuff. So I found an alternative, which is an adhesive roofing patch product called Peel and Seal, that you can buy at Lowe’s for 17 bucks a roll. The internet is STRONGLY divided on the merits of using such a product for this application.

The arguments AGAINST its use include:

  • There really are no sound-deadening properties
  • The applications have nothing to do with each other, butyl construction vs asphalt adhesive are not comparable in any way
  • The fumes will be toxic
  • It will not adhere and will melt and fall over time making a huge mess

The arguments FOR its use are:

  • Meh, it’s basically the same
  • It’s cheaper

My thought is that it probably does nothing to absorb sound inside the car, since the inside-facing surface is smooth aluminum. But I don’t see why it wouldn’t help isolate sound from protruding into the car (my reason for use), because if nothing else it’s a layer of stuff between you and the noise. It also bonds everything together so it certainly should help prevent rattles. On one hand, the company itself makes absolutely no claims for sound deadening and does not list that as even a possible use of the product. But on the other hand, half of the reviews on Lowe’s are from people who have used it for that purpose and are satisfied. I figured, what the heck, I’ll give it a shot.

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The first thing I realized while stripping out my interior is how much thought has already gone into sound deadening. Most of the surfaces have at least one, if not two layers of material on them already. The outer body panels have an absorbent material strategically placed on them, and the firewall has a large rubber and fiber insulator. There is a large rubber mat in the cargo area. I began to think that perhaps my efforts would be futile on top of what Toyota has already done.

But what the system seems to me to be lacking is one solid uninterrupted layer of ...something (except the carpet). Since that’s essentially what I’m putting down, I still think it will improve. I intend to do the entire floor and behind the door panels. I would be hesitant to put it inside the doors or on the ceiling, although I’ve seen installs where they did and held up fine.

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I’ll report back with results!