Replacing pad in engine compartment

[914helo]

I'm trying to get ready to paint the car soon and am trying to figure out if I want to put the pad back in when I'm done. My original pad is still in good shape and I like the fact that it reduces a little noise. But I'm worried that it sponges up water like that horrible pad in the trunk I got rid of.
If I don't put the pad back in will it be too loud in the passenger compartment? What about spraying on some trunk liner or something like that before I paint it? Any ideas? Thanks
Kent

[914GT]

Kent

I removed my old dirty nasty pad and stripped most of the firewall down to bare metal (I had to weld in new steel in areas). Then I primered it with epoxy when I did the car, then I put on two layers of a Dynamat-type material. Then I painted the engine bay base coat/clear coat with rest of car. I cut the new sound-deadening material using the old pad as a template. Inside the car I lined the back wall and floor with 1/2" thick Armaflex sheet insulation, which is available at HVAC supply houses. This combination gives good sound deadening and insulation.

[914helo]

Thanks Guy, that's a good idea. Did you put the insulation inside down before painting? I might as well do that now since I'll be painting soon.
Kent

[914GT]

Kent
I removed the original pad on the inside for repairs, primered the firewall, then put it back on. I didn't really bother painting it when I did the car as it gets covered up anyway. On top of the original pad I put on the Armaflex with 3M spray adhesive. The engine noise I hear comes through the back window.

[914helo]

Thanks Guy. Good info.
Kent

[Scooter311]

If you can make out the lousy picture, here's mine I made from sound/fire resistant material I bought from Summit. Came in a roll, less than 30 bucks, and I still have a bunch left over. Used the old one as a template.
Ignore the messy motor, it's gone now.

[BigD9146gt]

If you really care about noise, a buddy of mine got some lead sheet and layed it out in the inside of the fire wall. Very quiet, but like Guy said, the rear window does account for some noise. If its not your daily driver, take it off and just use some ear plugs for the long drives.

Cheers,Don.

[914helo]

I am worried about noise, and it's not my daily driver. Maybe I'll just leave it out. However, I'm more concerned about potential rust problems and if the stock pad is not going to be a factor for rust, I'll just put it back in. I just figured there were better options now than some 30-year old horse blanket that came with the car. Thanks
Kent

[SGB]

my lead sheet sound-proofing melted....

Actually, I am on a quest to tighten, bond, re-pad, etc. to achieve a level of genuine sound reduction (really excessive noise, anyway). I've got some lightweight material similar to that pictured that I am going to use to replace my existing pad. Speaking of lead, it is probably half the weight of the original stuff! I cut a small rectangle and put it into the top of the engine lid, in front of the drip tray. it made an enormous difference. I may put a few foam peices (bumpy mattress pad stuff) in the doors and other vibration prone, fairly flat panals. This all started after I got new shocks and realized it didn't have to be like a coffe grinder inside the car. Sure, I don't wanna add 50 lbs of stuff, but if I can use better, modern materials I can get a genuine improvement (I hope)

[914GT]

I really don't think the original pad did much for noise, more for blocking heat. If I remember the thing was made of some kind of rubber with what looked like asbestos fiber material stuck to it. Whatever it was I agree the thing probably trapped water against the firewall. I had enough rust to deal with back there. I've seen the firewall stripped clean and painted and it looks nice. If it seems noisier or hotter inside the car, put some additional insulation under the panel behind your seats.