I have discovered a very inexpensive sound insulation product called duct liner. It is simply the product that plumbers use to line the insides of return air ducts in forced air furnace applications to reduce noise transmission through sheet metal ducts. Most plumbing shops that make sheet metal ducting stock it. The product is available in various thicknesses, in my case I used the one inch material which cost only 90 cents Canadian per square foot. It is a fibreglass based product, grey in color, with a reinforced side on one side that is virtually black. It looks exactly like what you would find under the hood for insulation on an earlier pickup. I insulated the underside of my hood, as well as the doghouse with excellent noise reduction results. I also made a boot out of it that goes around the shifter boot underneath the truck. Under the hood where the cut edges of the insulation are visible, I smeared black caulking on the cut faces to match the reinforced exposed side and to make them more durable, before installing it. To attach it, I used aerosol spray contact adhesive. I also put a couple of coats of black spray paint onto the reinforced exposed side to make it more tear resistant. The finished hood insulation looks stock and made a noticible difference in noise by itself.

The doghouse area was a little more difficult as the product does lend itself well to curved surfaces. It wants to straighten out when not held in position and does not stretch. I ended up making a four piece blanket that fit together like a puzzle against the doghouse, using cardboard to make a template and then cutting the pieces of insulation from the template.

Richard S.
1995 NA Black Diesel Wagon