Noise levels on land

[robtherep]

Hello<br /><br />I am just curious about something I recently noticed when starting motors in the driveway. I ran 33h 1967 Rudy only for a short time since cooling system wasn’t working and it was very quite even out of water. When I ran 1980 50h Johnny it was an ear shattering exhaust noise.

 

[WillyBWright]

Re: Noise levels on land

The big difference is thru-hub exhaust. The loudest motor on muffs I ever owned was a 1971 Johnson 50Hp twin. MAN that thing barked!

 

[walleyehed]

Re: Noise levels on land

Better make sure you have water to the pump before starting...about 10 seconds of run-time without water will take most of the life out of the water pump.

 

[AguaSki]

Re: Noise levels on land

My 140 hp Johnson is loud too. My neighbor works nights so out of respect I have to be careful when I start the motor on the muffs.

 

[Dhadley]

Re: Noise levels on land

Make a cheapie "muffler" out of any piece of plastic. I use the bottom of a 1 gallon milk jug. Makes a world of difference.

 

[Dave Abrahamson]

Re: Noise levels on land

Originally posted by Dhadley:<br /> Make a cheapie "muffler" out of any piece of plastic. I use the bottom of a 1 gallon milk jug. Makes a world of difference.

Please elaborate oh wise one <br />Got any pics? Quieter on the muffs would be nice.

 

[artburr]

Re: Noise levels on land

Yes. Please elaborate.

 

[andy6374]

Re: Noise levels on land

I bought a very wide garbage can and I do everything in that. 10 times quieter that way and also provides back pressure for proper adjustment of idle speed out of the water.

 

[Dave Abrahamson]

Re: Noise levels on land

What do you do, tilt the motor up, slide the can under, fill the can, tilt the motor down into the can to flush it and then tilt the motor back up and dump over the can?

 

[andy6374]

Re: Noise levels on land

yep not too complicated, and you don't have to worry about exceeding the 1000 rpm limit that exist when using the muffs

 

[jafa]

Re: Noise levels on land

I use a 10 foot length of flexible silvered aircon ducting , just wide enough to go over the hub and held in place with an elastic band. <br />Works fine as a muffler just dont put it in gear.!!!!!

 

[scotty c]

Re: Noise levels on land

get a honda 4 stroke, they are so quiet<br />you could run it all day on the muffs and not <br />irritate anyone.

 

[phantoms]

Re: Noise levels on land

The problem I have with the trash can idea is that you're just recirculating the same water through the motor. I flush mine to remove the salt water I was running in, not recirculate it.

 

[joblo33]

Re: Noise levels on land

Noisiest motor on muffs for me: 1968 Merc 650 I4. <br />I used to test run motors in a plastic garbage bucket, but I was working on a 20hp that had the shift shaft out of alignment. It started in forwards at full throttle and now my garbage can leaks. I only run really small engines in cans now.<br />Eric

 

[Mark42]

Re: Noise levels on land

Originally posted by phantoms:<br /> The problem I have with the trash can idea is that you're just recirculating the same water through the motor. I flush mine to remove the salt water I was running in, not recirculate it.

I have run the motor in a trash can for 15 or 20 minutes. The water never even got warm. But I did have to leave the hose running a little in the can because the tell-tale shoots the water outside the can. <br /><br />Maybe bigger motors heat up the water quicker, but with the twin it seemed heat buildup was not an issue.

 

[Dhadley]

Re: Noise levels on land

I just cut the bottom off of a plastic jug and cut an X in the middle. Then take the prop off, remove the thrust washer, place the plastic over the shaft and repace the prop. Just put the nut on tight enough to keep the plastic in place.<br /><br />If we run a motor in a tub we still use the flushette. That guarantees cool water all the time.

 

[andy6374]

Re: Noise levels on land

I use the trash can test tank, but keep the hose going. It makes for a wet mess because it is constantly pouring over the side of can. But it's quiet, provides back pressure, and gives continuous cool water to the engine

 

[lakelover]

Re: Noise levels on land

Originally posted by Dave Abrahamson:<br /> What do you do, tilt the motor up, slide the can under, fill the can, tilt the motor down into the can to flush it and then tilt the motor back up and dump over the can?

OK, but when I made mine I got anal about it. I bought a cheapie plastic garbage can & drilled a hole near the bottom and mounted a hose bib type faucet in the hole with rubber gaskets. When I'm done, I drain it on the ground or with a hose to a spot further away. Takes a few minutes longer, but a lot easier than muscling around a trash can full of water & keeps your feet dry.

 

[phantoms]

Re: Noise levels on land

There is a "flush muffler" made for outboards that I read about in an older thread here. I can't find it on iboats, but here is a picture of it: <br />

<br />Here is the link to Overtons page for it here. If iboats carries it, could someone point me to it.

 

[robtherep]

Re: Noise levels on land

Wow this sure led to some interesting discussion thank you for the good ideas. I have used one of those empty brown olive barrels. They are used around here a lot for rain barrels (Eastern Ontario Canada) they are very strong and some are well shaped for this purpose. I think adding a facet at the bottom will be a worthwhile convenience. The faucet could be left open just enough so that a hose can run into the top keeping the water cool.<br />Since I got my first motor late Aug. 2005 I still don’t understand many of the basics like why would the one motor run so quiet when not submerged and the other so loud. What is the mechanical explanation for it and does it mean that the quiet one will also be quieter in the water. It’s the only one without foam in the lid (I’m sure lids not the right word). What is though hub exhaust and what are the other kinds?