# A little education, please.



## macawman (Mar 29, 2018)

I have discovered another part missing from my 56 Johnson 10 hp. Something called a Air Silencer & Loading Tube Assembly. What does it do when it is present and what happens if it's not?


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## nccatfisher (Mar 29, 2018)

macawman said:


> I have discovered another part missing from my 56 Johnson 10 hp. Something called a Air Silencer & Loading Tube Assembly. What does it do when it is present and what happens if it's not?


It basically does what it says, cuts down on intake noise.


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## macawman (Mar 29, 2018)

This motor has not run long enough to noticed an intake noise. If it we're missing from your motor, would you replace it?


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## Shaugh (Mar 29, 2018)

Motors run best when they're made the way the engineers wanted... a 2 cycle can be finicky about vacuum and back pressure... I'd do it.. This part ? I can't find a good exploded diagram for a 56...

https://www.ebay.com/itm/Johnson-Evinrude-5-10-hp-OMC-Outboard-56-57-58-59-Carb-Intake-Airbox/172409002218?hash=item28246098ea:g:-7IAAOSwXeJYKhHk&vxp=mtr

https://www.ebay.com/itm/52-53-54-55-56-Johnson-Evinrude-10HP-Outboard-Air-Intake-Carburetor/182344116589?hash=item2a748e696d:g:HEwAAOSwal5YHhYc&vxp=mtr


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## macawman (Mar 29, 2018)

According to the parts break down, it looks like this.


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## macawman (Mar 29, 2018)




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## Shaugh (Mar 29, 2018)

that's weird.. this one looks like it's pretty definite....

https://www.ebay.com/itm/USED-1956-10HP-EVINRUDE-203352-203353-AIR-SILENCER/282027309112?epid=1056579671&hash=item41aa233838:g:Oy0AAOSw5HJXKl2I&vxp=mtr

Is that part on it ?


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## macawman (Mar 29, 2018)

This is the parts catalog that a gentleman at Marine Engines for my year and model motor. The carb pages shows a unit like the picture I posted.

View attachment parts_10hp_john_376747.pdf


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## Shaugh (Mar 29, 2018)

Looks like they might have changed it mid year or something... there's a few on ebay from newer motors:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=0277437+Johnson&_sacat=0

it's the same part number..

Anyway I think the short answer is you want it... it helps normalize the air flow and probably helps in cold weather starting etc... not just silencing...


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## macawman (Mar 29, 2018)

I plan on replacing it. Just trying to figure out what it does.
Interesting that this assembly is never addressed or even mentioned in the service and repair manual that I'm using.


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## Pappy (Mar 29, 2018)

A majority of a 2-stroke's running noise comes from the reeds. The air box on these engines does two things. It smooths out the incoming air to the carburetor and it kills some of that reed noise. 
Can you run it without it? Yes, you can. Much nicer though with it in place.


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## macawman (Mar 29, 2018)

Thanks for the insight, Pappy. I'm all for less noise.


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## nccatfisher (Mar 29, 2018)

It will silence noise some, it isn't as noticeable with the cowl on. It also of course helps somewhat warming it up, but again with the cowl on not tremendously. Someone took it off over the years to do carb work probably on the water and either didn't bother to replace or lost it overboard. Many were lost that way. 

If you look at at this vid at about 2.24 mins you can see what it looks like. 

https://www.youtube.com/watch?v=HlKuwVcZc-8


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## Shaugh (Mar 29, 2018)

"Air Silencer & Loading Tube Assembly" I wonder what they mean by loading.... maybe to help boost the vacuum at the carb.... I know that's very important on some motorcycles... you can't even start them without the air cleaner installed...


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## macawman (Mar 29, 2018)

Yep, I wondered too. The Silencer part is sort of self-evident, but the loading tube thing lost me


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