Engine sound pad question... which one to use?
 

I purchased an Engine Compartment Sound Mat from our host: 911-556-891-01-M260, Latest OEM version (lighter-weight material),

My question is: The pad seems awful light and airy. Can anyone tell me if this pad offers as much sound deadening as the older heaver version of the pad?

The old pad number is 911-556-891-01-M136.

Thanks,
Arron

I just bought the shiny (non-OEM) one from Pelican. My shop says it works well, although I was wondering also the same question.

Has anyone ever compared the sound levels?

Buehler?

I bought the original, heavy sound pad a few years ago and it's already failing. Next time i will buy the new, lightweight version...

I dropped my engine the first time about a year ago, I changed from the aging heavy sound pad to the new OEM version, I never noticed a change in the noise level.

MHO. For effective sound attenuation, material should be applied to the surface, not just glued onto it. I vote for a material that sprays or brushes onto the bulkhead which is basically a flat, wide sounding board. Blanket-type materials may help slightly, but it's more effective reflecting heat (if shiny).

Sherwood

Spray glue will do just fine - I do that and then use tube stuff around the edges and in big X's on the panels.
- use the 3M stuff BTW - There are 2 types, I forget which to use.

I favor the new, lightweight, factory pad.

Also, a small air gap between the pad and the firewall could help or hinder sound isolation - it depends on the frequency, and is, as they say, non-trivial.

Foams will generally do a better job of inhibiting sound and heat transmission (the dual jobs of the pad) than will a fibrous material. I have no idea what the shiny after-market pads are made of - could be foam under the metal foil.

I ran without a sound mat for a couple of months & then installed the new OEM one from our host. Installed as Randy suggests. The difference - none vs new OEM - was significant. Much quieter imho.

Ian

Well then I guess I will install the pad this coming week. I plan on using the weather strip glue for the install. I¡Çm not a fan of the spray on gules as I have never had any luck with then holding over long periods of time.

I used no adhesive at all, and have had no issues. It will press-fit into place using the stock clips that are found along the upper edge of the firewall. You will save some aggravation doing it this way if you ever have to remove it again.

I noticed that there are two screw holes on the wall behind the engine. I¡Çm wondering if I can use the stock clips with two screws and washers to hold the mat in place.

Definitely. The mat will stay put. I'd forget the adhesive.

I just bought the silver foil backing with red piping perimeter trim.

Will shoot some pictures once I get it mounted and engine re-installed.

ANYTHING will be better than what the stock unit had deteriated to......rags of tar paper and fiberglass matting shards

I installed the four-layer “ultimate sound pad” yesterday. It does reduce noise, at least compared to the 22 year old crumbling and sagging original foam pad. Not about sure the acoustic effect of 5 or so pounds of shells, seeds and mouse poop that had accumulated in those sags. I did use 3M adhesive near the top end. The mat sagged between the metal clips on the firewall without it.

Paul

Before:

http://forums.pelicanparts.com/uploa...1181393260.jpg

After:

http://forums.pelicanparts.com/uploa...1181393282.jpg

I take it you dropped the engine to install?

No, room to install the pad wasn't too bad at all. I did spend a lot of time with the shop vac.

Paul

I should add more details.

There were some tricks. Getting the old pad out was easy as the adhesive had completely failed. I did try to contain the mess as much as possible with an old blanket over the motor and engine compartment.

I did:
Remove the air cleaner and cover (new air filter)
Remove hood shock (new hood shock)
Unbolted the bracket for the cruise control canister on the left side. This was key -- there is no clearance at all between that canister and the bracket for the hood shock. It took a lot of hand and wrist flexibility to get a 10mm wrench in there, but wasn't too bad.

Then, just slid the new pad in dry, and guided into position. I pulled the top of the pad down, sprayed in 3M spray adhesive where I could, and put a line of 3M Weatherstrip Adhesive along the edges, and pushed it into place, re-bent the clips, and put the other parts back on.

All together, about 2 hours, and would be less the second time.

Paul

I just sprayed mine with rubberized rocker panel goop. It looks good, and I won't have a crappy looking sound pad a year from now.

Of course, I like the noise.

I'm going to do mine with Dynamat, eventually. A friend installs car stereos and has pieces I can have for free. He says it's the best sound deadening material out there.

you mean on the interior side, right?

not a good idea, when regular Dynamat gets hot it falls apart, quickly. They make a special underhood version now for this very reason. As a matter of fact I know a guy that put it on the bottom of a metal sink to cut down noise and the hot water made it come apart.

Didn't know, thanks for the heads up. Isn't there a peel and stick neoprene material used for the same effect? That's what I'm looking for. I saw it used to line an inboard boat engine compartment, and I've seen similar stuff in car audio installs. It's about 3/8" thick, very dense with adhesive on the back.

I don't mind the engine sound so much, but the adhesive residue looks like rust and I want to clean up the engine compartment.

They make something for underhood use - it might be ok on the motor side of the firewall. Likely heavier than the stock pad tho.

One thing is you sure can't beat that price.

I am wondering what makes him say the product is the best one made - do you know? Or is it just 'company pride?

"He says it's the best sound deadening material out there."

Could be, for audio purposes, but it's heavier than some alternate materials. There are other sources for basically the same material, but w/o the Dynamat trade name attached (makes it pricier).

Sherwood

http://forums.pelicanparts.com/uploa...1185481213.jpg
I am doing a complete restore so I am going to put my sound mat on the other side of the sheet metal and leave this nice looking paint

That looks KILLER!

I have the bling bling Yo Boy foil backed - trimmed appbiz aftermarket sound pad - it's light - it deadens the sound on par with the factory pad, it doesn't fall apart, and I have seen no difference in engine temps even running a larger displacment, hotter cams and higher compression http://forums.pelicanparts.com/uploa...1185498937.jpg

Jeremy, did you buy the sound pad with the perimeter binding or without? How's the heat inside the car? Any different?

Thanks,
Mike

With binding - no difference in heat or sound

Sorry for all of the questions BUT did you try it without either sound pad? I don't have a pad now, and the rear seats do get a little warm. I'd like to keep the temps down, as my 7 yr. old daughter doesn't complain, but I want to keep her as comfortable as possible. If the pad will reduce temps inside, it's well worth it. If not, I'll keep my car the way it is (it sounds great!).

Thanks,

Once heat or noise 'hits' the sheet metal it is much harder to deal with. The sound pad on the engine side is going to be much more effective at both heat & noise control.

OTOH, that bare but finished texture does look good - so if you have carbs or something that let's you see the firewall, then you have to balance the visual w/ the heat/noise issues.

I prefer the Al foil type pads if you want that maximum "Roasted Chicken" bling effect.

I installed some Mylar-backed, 1" foam material out of the JCWhitney catalog; created a pattern with paper, tape and scissors, then transferred onto the material. Added Mylar tape to cover the cut edges. I believed I used contact cement on the bulkhead as well as the foam.

Since my car was out of commission for years when I did this, I can't speak for the sound or heat reduction of such a pad. As a wag, i'd say it reflects some heat and reduces some sound.

2-year old photo:
http://forums.pelicanparts.com/uploa...1185509178.jpg

Sherwood

Ha Ha - knew Randy would chime in - Do you think that's why I am getting all this HP? Maybe the foil backing is focusing the power waves from the flux capacitor...

I used the same stuff Sherwood used, but I got it at Pep Boys. I wasn't concerned about the sound, and was mainly concerned about a hotter passenger compartment with no pad. It has been in place a few years now and seems to work well.

Im going on the same principle that you put dynamat on the inside fo your doors to stabilize the metal and on the outside of the inner door panel to cut vibration from the stereo resonance

regular Dynamat works primarily by making the panel heavier

a heavier panel has a resonant frequency that is lower than a lighter panel; the peak amplitude ("Q") is also reduced

an analogy is sticking wad of asphalt on a kid's drum head - the metal panel is exactly like the drum head (since drummers tend to have strong forearms, this experiment is best carried out using a young kid)

I always thought that it was kind of like the the radar absorbant material on planes it would slow down the wave as ait traveled thru the material until the amplitude dropped off to 0

Just to add another theory;

I thought the added material changes the vibration frequency of the base material.

Quick. Someone call JCWhitney tech support for the answer. :)

Sherwood

"changes the vibration frequency of the base material."

- isn't that what I said??

Randy,
Yeah, but I wanted to say it too. :)

Sherwood

After reading this thread this morning I went out at lunch and pulled out my old, falling off and apart factory pad, then went for a drive. There wasn't any appreciable difference in sound levels.