Under-hood/cowl sound-deadening material?

[bjbrown]

In my restoration project on our 1980 spider, I removed the original sound-deadening material from the cowl vent area under the panel that holds the wiper mechanism (just in front of the windshield). Couple of questions about this area:
1. What materials are you using in your restorations to replace that original tar/asphalt-based covering? Is it necessary? Or, have you simply left the metal painted? Inside the passenger compartment, the tar-based material seemed to attract and retain moisture and promote rust. I've removed that too and plan to replace with a layer of dynamat-type stuff.
2. The trough under the cowl cover however is exposed to outside weather through the heater vent grilles and will therefore get wet in rain. Mine however, was not rusted (some minor surface rust in areas). Any concerns about putting sound-deadening material in that trough insofar as rust prevention is concerned?
3. Was that tar/asphalt covering originally for sound-deadening or did it have some other purpose?
4. Has anyone thought to apply sound-deadening material on the underside of the trough? Something like the dynamat product?

[4uall]

I am a big fan of EZ COOL

http://www.fiatspider.com/f15/viewtopic ... l&start=90

[DRUMMOND]

yes, it is for sound deadening. I put por15 on first then Rattle trap mat. make sure it has an aluminum top layer. do both inside and outside

[bjbrown]

4Uall, thanks. Did you use that EZ Cool stuff in the cowl trough? Any problems with it getting wet?

Drummond, do you have any information on where to source the rattle trap mat? Is it similar to the EZ Cool mat that 4Uall cited? You said to put it on the outside AND inside. When you put it on the inside (under the dashboard), is there any interference with the electrical or heater or A/C systems to watch out for? I currently have my dash completely stripped of everything down to the unit body being painted. It'd be good to get the sound deadening on before re-assembling anything.

[Wanting]

Is it easy to remove the cowl vent area?

I need to do this at some stage as my plastic vents are cracked and have overspray on them.

[RRoller123]

4Uall, thanks. Did you use that EZ Cool stuff in the cowl trough? Any problems with it getting wet?

Drummond, do you have any information on where to source the rattle trap mat? Is it similar to the EZ Cool mat that 4Uall cited? You said to put it on the outside AND inside. When you put it on the inside (under the dashboard), is there any interference with the electrical or heater or A/C systems to watch out for? I currently have my dash completely stripped of everything down to the unit body being painted. It'd be good to get the sound deadening on before re-assembling anything.

You don't want to apply any of these insulating foam products to the trough of the cowl, since they are not suitable for an application that is meant to become repeatedly wet. Use an Undercoating or a Truck Bed Liner spray product. I used undercoating on the cowl trough of mine, and used truck bed spray liner on the floor of the cabin, then EZ Cool over the TBL in the cabin.

Pete

[bjbrown]

Wanting, it's real easy to remove the cowl covering. There are six screws you can access with the hood (bonnet) open. Remove those screws and it should lift right out. Underneath, is the wiper mechanism assembly and the windshield washer plumbing. Remove the connectors to those systems and you can take the whole thing to your workbench. The plastic vents are held in place with two metal clips that just slide into place, and three rubber "screws" that push the vent up against the metal cowl.

RRoller123, Thanks for the suggestions on the cowl trough. I think that sounds like the right way to go - some material that will withstand repeated water incursion without self-destructing. I'm guessing that's why they used that tar-based stuff from the factory. My trough was surprisingly rust-free when I'd stripped it all down.

[RRoller123]

Protect the fenders as you fold back the cowl. This is what mine looked like 5 years ago when I first took a look under there. And take care not to damage the windshield rubber gasket as you both remove and reinstall the cowl. When you are reinstalling it, it slips under the gasket along its length.

Pete

[Wanting]

Thanks for the info on the cowling guys I was hoping it was that simple.

[DRUMMOND]

Rattletrap is not foam based it is rubber and aluminium and stretches to conform to curves, lay it like you wood a roof tile, with the flow of water. water should not be staying in the cowl area anyway that's a bigger problem. You can use truck bed-liner but you will not get the same sound proofing, so you might as well just paint it

Amazon sells it

[Funcar]

I will be using PRO 15 on mine. Will post pictures when I get home from holiday. I also replaced the washer hoses.I didn't remove the plastic grills as they could be brittle and I don't want to be looking for a new replacement. The spring clips came out easy so I painted them as well as the cowl. The posts on both ends were covered in a plyable putty and the conners under the windshield also was stuffed/sealed with the same type of putty.I have purchased plumber's putty to cover these areas.

[Broadsword]

I have not long ago taken the cowl off my car to find a great amount of dry leaves & twigs, but thankfully no tin worm.
It does not seem to have any sound deadener either.
Does this area, when treated with sound deadening material, improve sound levels in the car significantly?

[image]http://i920.photobucket.com/albums/ad43 ... 53x480.jpg[/img]

[Nitrate]

The original design, with the tar like material, is to deaden the vibration of the sheet metal. Replace with Dynamat. That will not absorb water and will accomplish the original intent. A really good article on the whole subject of sound deadeners and sound barriers related to cars can be found by doing a web search for Sound Deadener Showdown. RB

[PaulC]

Ban this Turkey for sure!

[Anbele]

I second PaulC for sure!