Underhood Sound Deadening Material

[California]

I cut down a scrap of half inch thick foam (neoprene?) floormat to where I could jam it into the underside of the hood, and it stays there when I open the hood. This thickness barely touches the air cleaner and misses everything else.

This helped reduce noise. The tractor is about as loud but the crispness of the 2-cylinder 'Yanmar hammer' is muted a little. It was less tiring to spend a couple of hours on the backhoe. It still could use a lot more sound reduction.

Has anyone found something that works to muzzle that racket? I wonder if you could paint bedliner right onto the lower, cooler half of the engine block? Think it would help?
View attachment 144896

 

[ultrarunner]

I cut down a scrap of half inch thick foam (neoprene?) floormat to where I could jam it into the underside of the hood, and it stays there when I open the hood. This thickness barely touches the air cleaner and misses everything else.

This helped reduce noise. The tractor is about as loud but the crispness of the 2-cylinder 'Yanmar hammer' is muted a little. It was less tiring to spend a couple of hours on the backhoe. It still could use a lot more sound reduction.

Has anyone found something that works to muzzle that racket? I wonder if you could paint bedliner right onto the lower, cooler half of the engine block? Think it would help?
View attachment 144896

Aviation use 3M material for sound deadening... kind of pricey in quantity. It's adhesive backed.

Some of the Hot Rod shops also sell stuff and don't forget JC Whitney...

 

[deepNdirt]

I haven't thought much of using a sound deadning materials, I'm not sure if anything would help? I would like to know why it is these 2-cyl sound this way? I mean when the jap's built this engine and fired it up... what was their take on this noise? Hmmm was it ---> Sounds good to me! and simply kept building and producing them,
or should it have been---> Hmmm som-um-dont sound right about this engine! we need tear it down check it out, Not!
I have found that running it at 1100 rpm is simi quiter, and then when runing it a 1800 rpm I dont even hear the hammer, but anything between these rpm's is teeth jaring,
and as Ultrrunner stated there is this product made its called Dynamat sound deadening material
my 29 year old son been using it for years in his car audio sound system, but I think he uses it to keep the ratteling down when they turn up their boom boom,

 

[Travelover]

..........................Has anyone found something that works to muzzle that racket? I wonder if you could paint bedliner right onto the lower, cooler half of the engine block? Think it would help?
View attachment 144896

A lot of noise tends to be radiated off the oil pan. Some diesels have a double layered pan with plastic sandwiched in between. You might find use something like this to dampen it:

Gutter Seal Tape

You could also use this same material on any other sheet metal panels that are vibrating and reradiating noise, if they are not too hot. Line any panels that you can with fiberglass or foam matting to absorb the high frequency noise (combustion cackle).

McMaster-Carr

 

[PILOON]

Self adhesive roof membrane has all the characteristics of being a good sound proofing material. Stuck on large pannels like a hood it will do wonders as it will cut out the drumming sounds.
Lead is a great sound blocker. (even a heavy foil will help)
3M's product is essentially dense foam with a thin lead faceing and self adhesive.
Cessna aircraft actually glued strips of tar paper in an X form on every large flat metal surface. Intent was to cancel the resonation of a large pannel.

I once used the 3M product under the hood and on the firewall of a Cessna and it was so effective that in flight I could hear the valves clacking in the engine in cruise mode.

On my tractor cab I glued thin foam under my headliner to cancell all drumming and vibration--very effective!

Gravel guard, available in spray cans, would be good on any large areas like hoods and firewalls as well. Kinda messy however to spray cleanly.

For shure, firewall and hood are the 2 areas that would be most effective.

Ever notice that auto makers simply add felt underpadding under the carpets in the upgraded versions of a specific cars to quieten or deaden the road noise? it works!

 

[ultrarunner]

The product I used on my Model A Ford is 3M Y-370 It really made a difference.

A friend has ordered supplies from this place... I have never used them and can't make a recommendation for or against...

Soundproofing & Noise Control Materiels Prices

 

[Gary Fowler]

Just be careful when applying insulation to the crankcase and engine compartment so you dont trap heat in the engine and restrict air flow around the engine and cause overheating of the engine and oil. Lots of cooling comes from the air cooling of the engine.

 

[California]

Good point. Maybe what's needed is shrouding, not anything that touches the block.

My US Yanmar is the same as deepNdirt's red YM2000 shown in his avatar above, but mine doesn't have that white mesh side panel visible in his. (Even in its original sales brochure photo). And the 'B', revised versions of the Japanese big twins had more complete side covers than deepNdirt's. I expect the reason was the engineers (or the marketing branch) finally had a revelation like what deepNdirt said.

"Hmmm som-um-dont sound right about this engine!"

so they added those mesh panels to contain the clanking a little. It needs a lot more.

For anyone unfamiliar with the extreme 'Yanmar Hammer' clank-clank-clank, there are two sound recordings at the bottom of the page referenced from my sig below.

 

[Neat 1500]

Good point. Maybe what's needed is shrouding, not anything that touches the block.

My US Yanmar is the same as deepNdirt's red YM2000 shown in his avatar above, but mine doesn't have that white mesh side panel visible in his. (Even in its original sales brochure photo). And the 'B', revised versions of the Japanese big twins had more complete side covers than deepNdirt's. I expect the reason was the engineers (or the marketing branch) finally had a revelation like what deepNdirt said. so they added those mesh panels to contain the clanking a little. It needs a lot more.

For anyone unfamiliar with the extreme 'Yanmar Hammer' clank-clank-clank, there are two sound recordings at the bottom of the page referenced from my sig below.

Aww and here i thought you loved that clank-clank-clank? well i do,at every opportunity i will show the short clip i have on my blackberry. people that are mechanically inclined ask if it has conrod bearings in it!!! Hehehehe

 

[careyo63]

I Agree Neat love it and at least hardly no viberation.Just pounding out the power. I had a accident at the first part of the this year and lost most of my hearing in my left ear.Worst case I'll just have to use 1 right ear plug.

Carey