FAQ: Underhood Insulation Pad/Liner

Anyone ever let their car run for a while (not in the sun) and then felt the outside of the hood? It barely even gets warm, let alone hot enough to effect the paint in any way that the sun wouldnt. As a matter of fact your engine would probably have to be on fire before it got the hood hotter than the sun does.
Ive had my hood insulator off since i bought the car over 3 years ago, and my paint is still as shiny/smooth as ever. I also like to hear the sounds my engine/trans are making, whether it be good or bad.
Take it off.

Tyler, are the hoods on the Park Ave's aluminum like on the rivs?

Thanks for your comments.

Based on what's posted I've learned it's likely the hood pad's job is noise insulation. It is probably made as it is so that it does not contribute to a fire or whatever in case one were to break out. For the rest of you reading this, the plastic wire looms on the cables under the hood are only good to a bit higher than boiling (212 deg. F is boiling). I kinda doubt the hood pad gets much hotter than 150 - 160F except in the Mojave Desert and even then not much hotter.

Also thanks for pointing out that the carbon fiber fabric on eBay is not carbon fiber. I'd have been, well, torqued had I bought that stuff. Do you think that some fabric offered is the plastic stuff and maybe other fabric is authentic? For instance, there are people who supply the stutff for folks who fab their own surfboards...

I need to think about this a little. An attractive, non-flammable fabric.

I'd appreciate any further comments and thanks to all who've made remarks so far.

Albertj

Re: carbon fiber, Kevlar, and Nomex type materials, the dead give aways are the words "vinyl" and "carbon fiber design" in the description. Also the low price, and the fact that the genuine materials usually don't come with adhesive backing suggests this is an imitation product. They have to tell you this in the item description.

Genuine adhesive backed materials exist, but you will pay dearly for them. If I were using carbon fiber to laminate the hood insulation panel, I'd consider coating the panel in clear epoxy, then applying the material, followed by a final coat.

here is a site selling large remnants of fire retardant fabrics

http://store.magnafabrics.com/Fire_Retardant_Fabrics-Sheeting.html

here is another site selling fire retardant fabrics - primarily curtain fabrics:

http://www.fabricdirect.com/acatalog/metal-glow-satin.html

A third site with "theatrical" fabrics - focus on the code IFR (Inherently Fire Retardant) fabrics.

http://www.sewwhatinc.com/eswatches.php

And oh by the way here's a site with replacement rear package shelf covers for $40 or so

http://www.anycovers.com/custom_polycarpet_rear_dash_cover.html

So with what I have learned so far a couple yards of this stuff ought to work fine to recover the pad:

http://setshop.com/photo-backgrounds/duvetyne/6411y-black-flame-retardant-duvetyne-54-x-yard.html

54" wide by 2 yards is $21.- plus shipping...

Hmm...

Albertj

Mr.Riviera wrote:

Tyler, are the hoods on the Park Ave's aluminum like on the rivs?

Pretty sure. The reason i say this is i was filling the regals washer fluid in the dark one night, i have a light with a magnet and it stuck to the hood. A few days later i was under the hood on my park avenue and put the light on the hood to see if it would stick and it wouldnt.

Thanks for the info guys. I'm glad I checked here first before I made a boo-boo

Here are some additional options for carbon fiber fabric and other high temp materials:

http://www.mcmaster.com/#fabric/=d0nt90

Click the link and select option 3480: 'Fabrics and Brake & Clutch Lining' at top of page.

You should see the following materials:

Vermiculite-Coated Fiberglass Fabric

This fabric can withstand very high temperatures and offers protection from sparks and molten metal splash. Ideal for welding shields, curtains, blankets, and gaskets. Material is woven. Maximum temperature is 1500°F. Color is tan.

Sold by the ft from a 60" wide roll: $10-20/ft depending on thickness.

Carbon Fiber Fabric

Material is at least 50% polyacrylonitrile. Color is black. Sheeting resists flames and molten metal splash, making it ideal for protective clothing. Max. temp. is 800°F and can provide a protective barrier for as long as 2 minutes in temperatures up to 2600°F. Strips are good for high-temperature seals and heat insulation. Max. temp. is 700°F when oxygen is present and 5000°F when oxygen is not present.

Sold by the ft from a 60" wide roll: $25/ft for .020" thickness.

There are some more affordable options under 3479: 'Fiberglass Fabric'

Also check 3478: 'Leather and Natural & Synthetic Fabrics' for Kevlar and Nomex fabrics, sold as Aramid Fabric.

High temp thread is sold under 3481: 'Sewing Accessories, Fabric & Ceramic Insulation'

Thanks Aaron...I really appreciate your advice and interest.

Aaron, if I remember correctly, you removed the OEM insulation under your hood, right? Do you have any plans to put something back up there or are you leaving it naked?

Leaving it naked. It's been off such a long time with no adverse effects, and that's with bare headers creating lots of engine bay heat. The main reason I've found for keeping it would be the same as for keeping the engine cover - to absorb sound.

I personally like to hear every nuance of noise coming from under the hood. The injectors, the belts spooling up, even the valves can be heard opening & closing if you listen. It helps to identify things not right. The only thing I don't enjoy is the exhaust note, so I try to keep that as quiet as possible. The hood insulator doesn't do much to affect the exhaust note.

AA wrote:

Leaving it naked. It's been off such a long time with no adverse effects, and that's with bare headers creating lots of engine bay heat. The main reason I've found for keeping it would be the same as for keeping the engine cover - to absorb sound.

I personally like to hear every nuance of noise coming from under the hood. The injectors, the belts spooling up, even the valves can be heard opening & closing if you listen. It helps to identify things not right. The only thing I don't enjoy is the exhaust note, so I try to keep that as quiet as possible. The hood insulator doesn't do much to affect the exhaust note.

same here

Thought you guys would get a kick out of seeing my mutilated hood pad. Thanks to some sort of rodents, I would suppose. It was like this when I purchased the car. I finally had enough of looking at it and ripped it off over last weekend.

Isn't that above the SC belt? Likely a shredded SC belt did that damage, like mine suffered shortly after I replaced the crappy original pad with a new $90 pad...

The last picture is above the belt, yeah. I wouldn't doubt that's the cause of that particular hole because the SC belt was indeed snapped when I bought the car.

Randy T. wrote:

Yeah, they are aluminum. We call it the 5 minute hood mod.

I just took the padding off my hood last weekend. Have you noticed any real heat differences after removing? So far i've only noticed that I can hear under the hood better, which I like.

Picked up a near pristine hood pad for the 95 Riviera at a pick-and-pull yard today. Almost missed out on it as the hood latch on the Riviera was busted and we had to get "serious" with it to get the hood opened. Every other wrecking yard Riviera I've seen has had a ruined pad, so I nearly passed on forcing the hood. But I'm glad I did... $11

I actually like the look of the pads, when they are in good shape. But when they start to deteriorate, get dirty, or damaged from a thrown belt.... they do really look bad and take away from an otherwise clean engine bay.

Al

Installed the salvage, but good, pad today after painting the "Riviera" embossed script. I used Testors "Pontiac Engine Green" from one of their higher end model paint lines. It is VERY close to the Light Jadestone exterior of the car. My original pad was shredded above the belts from a previous owner's belt failure....

I like the pad as I think it dresses up the underhood area. But it has to be clean and in good shape to really contribute in a positive way. Once torn up or left dirty, it starts to detract from the underhood aesthetics.

I agree that I believe the pad is there for just two reasons, first as a sound insulator and second for looks. I don't think it has any significant benefit with regard to heat, although I guess it does no harm in that regard as a little extra insurance.

Nicely done. Improves and impresses.
What stabilizer have you installed? Like it?

Al, that looks awesome

Just as an aside (may have said it before in this thread), I took the hood insulation out of my Riv a few years ago & it has had no effect on the heat level of the hood, the exterior paint, etc. My hood's paint quality really hasn't changed at all since I took it out a few years ago.

The main difference I see (besides the engine being way louder) is that when there's snow or ice on the hood and I turn the car on, after the engine heats up for a while, I can see circular areas on the hood where snow/ice melts while all the other snow/ice remains in place. I think this has to do with the conical shapes of the underhood sheet metal (if you've taken your insulation off, you know what I mean).

Rivit wrote:

Nicely done. Improves and impresses.
What stabilizer have you installed? Like it?

Here you go:

https://rivperformance.editboard.com/t109-write-up-installing-a-front-strut-tower-brace-stb?highlight=brace

So, bummer update.... had my accessory belt separate and beat a hole in the "new" hood bad above    Fortunately the hole is pretty well defined and only about 3x4 inches. But is still a bummer.

Instead of throwing this pad out, or living with the hole, I think I'm going to see about perhaps covering the hole with a piece of ABS as a sacrificial piece when the inevitable belt failure happens again.

Al

al_roethlisberger wrote:

So, bummer update.... had my accessory belt separate and beat a hole in the "new" hood bad above     Fortunately the hole is pretty well defined and only about 3x4 inches.  But is still a bummer.

Instead of throwing this pad out, or living with the hole, I think I'm going to see about perhaps covering the hole with a piece of ABS as a sacrificial piece when the inevitable belt failure happens again.

Al

...or maybe an aluminum plate onto which you put a decal of the belt routing diagram? Rivet it on with washers on the back to hold rivets?

AL
when painting the pad, did you brush it on?
Take several coats?
Are the lines able to be defined reasonably along the edges?
Hoping to dress mine up once the weather improves.
Thanks,
Jbird

jbird wrote:

AL
when painting the pad, did you brush it on?
Take several coats?
Are the lines able to be defined reasonably along the edges?
Hoping to dress mine up once the weather improves.
Thanks,
Jbird

Yep, brushed it on. It took 2-3 coats. The fabric soaked it up on the first coat, but the second full coat and third touch-up coat went on more solid.

The embossed "Riviera" was clear enough to get it very close without much effort on both the pads I painted. I painted one the light teal that matches the car's paint. which is the one the belt just ate    ... the other one is silver, but that pad wasn't as pristine.

And of course, I painted them OFF the car. I don't know how one could pull it off still mounted to the hood   

Al