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

[Poohsan]

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

[mtbguy]

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?

[azasadny]

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...

[Scott R]

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.

[911pcars]

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

[randywebb]

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.

[imcarthur]

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

[Poohsan]

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

[ZOA NOM]

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.

[Poohsan]

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

[ZOA NOM]

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

[Rusty Heap]

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

[PSJoyce]

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:



After:

[sig_a]

Originally posted by PSJoyce
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:



After:

I take it you dropped the engine to install?

[PSJoyce]

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

Paul

[PSJoyce]

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

[Porsche_monkey]

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.

[defcon65]

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.

[randywebb]

you mean on the interior side, right?

[Scott R]

Originally posted by defcon65
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.

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.