How to quiet noisy exhaust?

Discussion in 'Diesel Engines' started by Brands01, Jan 12, 2010.

  1. Frosty

    Frosty Previous Member

    If It works,-- do that. But your own idea of a after market filter would be best,something off a Landrover etc etc.

    Maybe a rubber hose 2 meter to the back of the boat.
     
  2. Brands01
    Joined: Nov 2006
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    Brands01 Senior Member

    Thanks Frosty, I was thinking about one of those barrel filters from a landrover could be a good fit, and easy enough to come by - something from a truck is likely to be a bit large.
     
  3. Frosty

    Frosty Previous Member

    The orginal land rover was an oil bath. Like I said quietening a single is difficult and a straight forward filter may not be 100%. For cheapness and for experiment some cheap hose laid to the back somewhere where you cant ear it.

    Car top hoses can accommodate sharp bends without compromising air flow.
     
  4. Brands01
    Joined: Nov 2006
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    Brands01 Senior Member

    I've got a bid on a landrover oil bath on ebay as we speak :)
     
  5. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    "Then use one of the Vetus top pieces high enough so the exhaust drains overboard."

    ...are you referring to the water setarator type of units, we use them on small gensets, but I have not used one on a 40hp motor.

    Are they suitable for such hp?
     
  6. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    you dont want to be using an oil bath cleaner on a boat ( with the oil in it that is)
     
  7. Frosty

    Frosty Previous Member

    You don't need much --oil bath maybe misleading,--the air just goes over it infact it does'nt need the oil at all.

    A boat doesnt need an iar filter anyway its just the silencing affect thats required
     
  8. apex1

    apex1 Guest

    Do not install a air filter. You restrict airflow.
    When the simple hose does the trick, do it.
    The Vetus separator was a sensible investment.

    And do´nt forget to renew the engine mounts anyway.

    Regards
    Richard

    Lubs,
    yes they can handle that.
     
  9. Frosty

    Frosty Previous Member

    This is a 36 HP and the owner has decided to fit the engine with a gauze type cleanable filter called an "oil bath" off a 2 liter engine to silence intake noise.


    'Any' restriction of air flow will not affect this installation in the slightest.
     
  10. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    hey Frosty
    last time i checked what was called an oil bath had an oil bath in the filter and the air rushed down to it and made a 180 degree turn so dropping the dust into the oil ( 60's car stuff)
    Hence my first thought was a yacht healed or pitching and the engine swallows the oil...ouch

    A gauze screen would be fine as you say.
     
  11. Frosty

    Frosty Previous Member

    Hi power, yeah thats about it but those Landrovers went through some serious angles. The oil is just a about 1/2 inch deep it wont get sucked up even if he uses the oil bath.

    Anything stuck on the end of his intake will improve it.
     
  12. apex1

    apex1 Guest

    I beg to differ. Even a low resistance air filter HAS a resistance. The oil bath filter has a higher one than a simple paper filter.
    The engine will run rich when you "choke" the air intake. It may coke, and smoke.
    Not a good idea.
    To get rid of the resonance, the hose has proven to be sufficient. So, why more effort than that?

    Regards
    Richard
     
  13. Frosty

    Frosty Previous Member

    Kistinie is that you? what have you done with Apex?
     
  14. Brands01
    Joined: Nov 2006
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    Brands01 Senior Member

    I used to have a landrover, and Frosty is quite right, they go through all sorts of angles without any problems. Its a very deep unit with only a tiny bit of oil in the bottom.

    My boat isn't a sailing boat either, it only gets used on the harbour, so any angles approaching what a landrover is capable of would be extremely rare.

    I've been experimenting with different hose lengths on the end of my existing air cleaner. Any length improves the situation, but the best result was a length of hose about 1.5 metres with my old polypropelene water lock unit on the end as a sort of expansion chamber (no water inside, of course!) That was very quiet at idle, but did start to resonate as the revs increased. Speaking of resistance, I'm pretty sure that setup would have alot of resistance - probably more than replacing the existing aircleaner with a landrover unit with a shorter hose.
     

  15. Kaluvic
    Joined: Jan 2010
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    Location: Yemen and Lebanon

    Kaluvic New guy

    I went to a reasonable amount of trouble to isolate all my exhaust components (after the manifold) from the structures of the boat.
    I used motor mount type isolators and bits of rubber sheets.
    Your problem sounds more intense than what this may solve, but I'm new here and it gives me a chance to figure out how to post pictures…and I’m board!
     

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