Best sound deadening material for motor box?

M

model14

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I have recently built a new motor box from 1/2" plywood to cover my 2.5L Mercruiser motor. What is the best sound deadening material to use on the inside of the motor box? Hopefully it is something I can get at Lowes :).
Thanks,
Richard
 
Bondo

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Re: Best sound deadening material for motor box?

model14 said:
I have recently built a new motor box from 1/2" plywood to cover my 2.5L Mercruiser motor. What is the best sound deadening material to use on the inside of the motor box? Hopefully it is something I can get at Lowes :).
Thanks,
Richard
Click to expand...

Ayuh,.... Back when I built my motorbox, I happened to find a huge pile of closed cell shippin' foam wrap in my dumpster divin' excursions,...

I believe Staples carries it in several thicknesses,... The usual 1/8" stuff needs multi-layers to work,...
 
further

further

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Re: Best sound deadening material for motor box?

I used this stuff on my outboard motor cowling and it worked real well. Kinda pricey though. I ended up sourcing it locally for about $25 cheaper than crutchfield

Dynamat Dynaliner (1/2" thick) One 54" x 32" sheet at Crutchfield.com

I'm looking for something different though to use on my new boat with an i/o for the underside of the sunpad so will be interested in what you find.
 
Woodonglass

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Re: Best sound deadening material for motor box?

I'm NOT an I/O guy so I don't know what your Space limitations are but...I am a C.O.B. and I do know this stuff works great for killing sound...
6a0120a85dcdae970b0120a86d6b2b970b-pi


You could staple or Glue it to the interior and it wouldn't show grease or dirt and it's fairly inexpensive.
 
greenbush future

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Re: Best sound deadening material for motor box?

Woodonglass said:
I'm NOT an I/O guy so I don't know what your Space limitations are but...I am a C.O.B. and I do know this stuff works great for killing sound...
6a0120a85dcdae970b0120a86d6b2b970b-pi


You could staple or Glue it to the interior and it wouldn't show grease or dirt and it's fairly inexpensive.
Click to expand...
How is this material do with heat, and petroleum exposure? Looks like it could be a great solution for one of my dog house re-builds.
 
Ned L

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Re: Best sound deadening material for motor box?

Uhm, the stuff that has been mentioned so far here is very flamable, and not what I would put in an engine compartment. I'm not saying that it needs to be non-flamable, but I wouldn't deliberately choose something that will burn like a birthday candle (or worse).
There are true soundproofing materials that are appropriate for this. Two that I've seen in the past are a foam glass material (looks like foam rubber, but is actually glass), and a lead/foam composite material that does offer flexibility (heavy though).

As for that gray waffle foam material, check out "Station Nightclub fire"................
 
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further

further

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Re: Best sound deadening material for motor box?

Something foil faced which would deal with the heat well would probably work well. I'd be concerned with that sound deadening foam breaking down and getting sucked up in places where it shouldn't be
 
Bondo

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Re: Best sound deadening material for motor box?

Ayuh,...... This is the stuff I've used,....

S_1956P_L.jpg


The 1/8", 1/4" stuff is great for curtains, 'n linin' plywood, under vinyl,...
My ole motorbox has 2 layers of 1/4" stapled inside, 'n another layer under the vinyl coverin',...

I found a bunch of 1/2" stuff at a steel yard dumpster,....
Lined my outboard motor cover with it,...

Great stuff that hasn't started to break down in anyway, Yet,...
Years in service,...
 
73Chrysler105

73Chrysler105

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Re: Best sound deadening material for motor box?

further said:
I used this stuff on my outboard motor cowling and it worked real well. Kinda pricey though. I ended up sourcing it locally for about $25 cheaper than crutchfield

Dynamat Dynaliner (1/2" thick) One 54" x 32" sheet at Crutchfield.com

I'm looking for something different though to use on my new boat with an i/o for the underside of the sunpad so will be interested in what you find.
Click to expand...

There is a foil covered dynamat that can be used in engine compartments that would be best to use.
 
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juryduty

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Re: Best sound deadening material for motor box?

Somebody on another forum recommended this stuff called Noxudol, website is Noxudol | Noxudol USA

It is sound-deadening paint, flame retardant, goes on thick.
 
Woodonglass

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Re: Best sound deadening material for motor box?

Good Point about the "Flames" Like I said NOT an I/O guy so never Thunked about dat!!!!! How about the Foil Faced Insulatation board??? It's fire resistant and not to pricey. You can get it @ Heat and Air distributors.
polyisocyanurate-foil-faced-insulation.gif
 
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gm280

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Re: Best sound deadening material for motor box?

Just for information, my neighbor has a 15HP Johnson O/B (1991 model I think) and had sound deadening in the cowling. And that foam, which looked very similar to the egg foam posted earlier on here, was deteriorating and literally crumbling with just a lite touch. I told him to remove all of it because the foam would easily get pulled into the carb obviously with the vibration from just running. So whatever type sound deadening you choose, make sure you check it out over the season(s) or make sure it is in some type foil or clothe covering to prevent deterioration and ingesting into your engine... Not sure what the foam would do to the engine and/or carb! JMHO :watermelon:
 
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model14

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Re: Best sound deadening material for motor box?

Okay, I am going with the "cheap" solution. $15 for enough 1/2" neoprene like material used in gym exercise mats to cover the inside of the box. My budget for this restore will just not allow spending $100 on sound deadening material. Who knows, it may work. It's not like it will be hidden from view all of the time. I always lift the motor box before each start, so I can see if there is deterioration or other problems. DAP contact cement worked well for putting it in place. I will let you know in a few months how it worked out. Thanks for the inputs.
Richard
 
mwe-maxxowner

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Re: Best sound deadening material for motor box?

I, and maybe others too, would like some pictures of the finished product. There is nothing but a bench seat between my motor and the deck where everyone hangs out. It doesn't fit closely to the hull sides, it is open on each side. As a result the motor noise is starting to get on my nerves. I want to build a panel that spans the width of the hull and scribe it to fit the contours of the hull, splash well, deck, closely, and insulate it with something. I also want to put something on the backside of my splashwell lids and motor covering lid.
 
jc55

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Re: Best sound deadening material for motor box?

Dynamat is the best, but car enthusiasts use "peel and seal" from Lowes or Home depot as it's closest replacement for the money. My problem hasn't been the material, it's always been the adhesive in the past. (I'm with gm280 on crumbling stuff).

Exercise mats sound like a good idea. wonder how they'll hold up. Those 1/2 green foam 4x8' sheets with the threaded looking outer layer, would probably work great.
 
Scott Danforth

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redneck joe

redneck joe

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Re: Best sound deadening material for motor box?

Scott Danforth said:
the best stuff to line your motor box for both sound and heat comes from Soundown - peace and quiet for architectural, marine, & industrial applications It is what is used by the marine OEM's

unlike dynamat which is not used in the OEM marine industry

http://www.soundown.com/Section 2 PDFs/2.1 PDFs/Acoustic Absorp Foam.pdf

http://www.soundown.com/TECHSHEETS/Microlite 2010.1.A.pdf
Click to expand...



not easy to buy/price. I've gone to 5 of the vendors websites and refers me back to Soundowns page....
 
B

britisher

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Re: Best sound deadening material for motor box?

Go to IBoats and search 'insulation'. They sell Soundown sheets.
 
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