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  1. #11
    kid's inheritance's Avatar
    kid's inheritance is offline Registered User
    Location : San Carles and Windermere
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    Why do modern helm displays show most information twice?
    Why do we persist in having our own separate vocabulary?
    Why do boat bits have two or three names for the same bit?
    Why is any cleaning product that has a picture of a boat on it 3 times the price of one with a car on and 5 times the price of one with a house on it?
    Why if every helm has a seat are the controls never at foot level?
    Why haven't fuel tanks holding 000's of fuel lockable?
    Why don't people who all love boats talk to WAFI's/frothblowers?
    Why are all of us frightened to work out how much these bl##dy things work out per hour we are on them?
    Why is the forecast so rubbish for the longest weekend of the year?
    Rob

  2. #12
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    Quote Originally Posted by DAKA View Post
    Have we ever had a silly question thread ?
    Just thought we could post daft things that niggle you but not worth a post on their own.

    Like if my engines are running 35-50 psi , why doesn't the dipstick get ejected out like a spear gun harpoon
    Ive got a welding question?

    Can i weld a human arm back onto a shouler using a finger as a filler rod.??
    I wonder how much deeper the ocean would be without sponges.

  3. #13
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    If the shoulder and arm are from different people you need to use a dissimilar finger.

  4. #14
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    Quote Originally Posted by DAKA View Post
    Like if my engines are running 35-50 psi , why doesn't the dipstick get ejected out like a spear gun harpoon
    Now that is a truly silly question.

  5. #15
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    Quote Originally Posted by DAKA View Post
    Have we ever had a silly question thread ?
    Just thought we could post daft things that niggle you but not worth a post on their own.

    Like if my engines are running 35-50 psi , why doesn't the dipstick get ejected out like a spear gun harpoon
    I thought all your threads were silly questions of colreg Trolls?


    And the answer to your question is that 50psi isn't even enough to get the oil up the dipstick vent is it? AND the dipstick isn't sealed in the tube even if the pressure was adequate.
    Boaty junk clogging up your shed or lockers? Chuck it in http://groups.yahoo.com/group/Marinaskip

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  6. #16
    Lakesailor's Avatar
    Lakesailor is offline Registered User
    Location : A North Country Lake
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    Quote Originally Posted by rafiki_ View Post
    Actually, there should be a breather in the system, so there is no substantial pressure in the crankcase.
    Now I'm worried.

  7. #17
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    I can't not answer this any longer.

    The only significant source of pressure in the crankcase, and thence the sump, is from blow-by. If there's a lot of it, your engine is tired.

    The reason the oil pressure doesn't push the dipstick out is because the dipstick is a tube which goes into the sump, and the oil in the sump is not pressurised. It is simply a reservoir. In fact, you don't even need to keep the oil there if you don't want to. You can have a dry sump system, which is used mainly on racing cars to prevent oil starvation due to surge. It also reduces winding losses, but perhaps this is going into too much detail.

    The oil in the sump of your boat is at, or very close to, atmospheric pressure until it is drawn from the sump, by the pump, where it is pressurised. The resistance against which the pump generates the oil pressure seen on the gauge is provided by the limited escape routes for the oil after the pump. The primary routes are the clearances in the engine's bearings into which the oil is fed and the jets which squirt oil onto the cam lobes and onto the bores under the pistons.

    Once the oil has escaped from the little spaces between the bearing shells and the crankshaft, camshaft and whatever other delivery points it's been pumped to, it is no longer pressurised as it has escaped from the resistance causing tight spots, and dribbles, at atmospheric pressure, back to the sump.

    The sump and the oil within it does not get pressurised to tens of pounds per square inch by the oil pump.

    Here is a picture. It is of an engine. It shows the pressurised oil ways as straight lines and the unpressurised oil as drips making their way back to the sump and as wavy lines once in volume in the sump.


  8. #18
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    Thankyou Simondjuk

    Very comprehensive and easily understood response .


    Just need searush to realize there is always more to my posts than appears at first glance
    .

  9. #19
    Davy_S's Avatar
    Davy_S is offline Registered User
    Location : Greece (Ionian)
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    Most dipsticks do indeed start to blow out of the hole, it is because they have oil on them that they slip back down again. that is why manufactors fit a loop at the top of them, so that you can tie them down. It should be obvious really.

  10. #20
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    Talking ?

    Can you only cook pancakes in your air filter?

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