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  1. #1
    Join Date
    Mar 2010
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    68

    Default 4 hp maranier over heating

    Hi all
    I have a 4 hp Mariner on my tender which starts on the second or third pull & runs ok for about 15 mins . It seems to build up heat smokes then stops,water pumps out of the tell tail ok.Could it be a blockage in the water jacket, in the engine .Maybe a salt blockage.I got the engine used of ebay just run it up in a tub for ten mins it seemed ok.Bad move .Any way to flush it through any advise would be appreciated

  2. #2
    Join Date
    Sep 2002
    Posts
    12,262

    Default

    Most likely to be the water pump that is blocked. Flushing rarely works unless you already have some water flow.

    If you release the gear shift arm, drop off the lower unit, you should be able to clean out the pump. It's a good idea to change the impellor whilst it's apart.

  3. #3
    Dabhand is offline Registered User
    Location : South Devon
    Join Date
    Jan 2010
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    64

    Default

    Probably also worth checking the thermostat is opening and closing correctly and is not clogged with debris. Easy to check the thermostat using a saucepan of water on the hob.

  4. #4
    dpb's Avatar
    dpb is offline Registered User
    Location : Poole, Dorset
    Join Date
    Feb 2007
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    551

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    Quote Originally Posted by Dabhand View Post
    Probably also worth checking the thermostat is opening and closing correctly and is not clogged with debris. Easy to check the thermostat using a saucepan of water on the hob.
    +1

    Mine had corroded solid.

    When I found how much the stat was I left it out, didn't seem to make any difference really!

  5. #5
    Join Date
    Mar 2010
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    68

    Default

    Hi can you explaine where the stat is please

  6. #6
    VicS is offline Registered User
    Location : Home: Kent. Boat: Chichester
    Join Date
    Jul 2002
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    32,047

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    Quote Originally Posted by tichmarshjohn View Post
    Hi can you explaine where the stat is please
    You dont give any info about your engine.

    2 stroke or 4 stroke ?
    serial number ?

    4 strokes have a thermostat under a cover on top of the head

    Younger 2 strokes dont have a thermostat . Older ones do but you have to remove the exhaust cover to access it.

    Get the serial number and then look at http://www.boats.net/parts/search/Me...ner/parts.html

  7. #7
    Join Date
    Mar 2010
    Posts
    68

    Default

    Hi my engine is a two stroke 4 hp mariner i can not find a thermostat

  8. #8
    Hadenough's Avatar
    Hadenough is offline Registered User
    Location : No fixed abode
    Join Date
    Jan 2011
    Posts
    1,148

    Default

    Quote Originally Posted by tichmarshjohn View Post
    Hi all
    I have a 4 hp Mariner on my tender which starts on the second or third pull & runs ok for about 15 mins . It seems to build up heat smokes then stops,water pumps out of the tell tail ok.Could it be a blockage in the water jacket, in the engine .Maybe a salt blockage.I got the engine used of ebay just run it up in a tub for ten mins it seemed ok.Bad move .Any way to flush it through any advise would be appreciated
    Had the same problem with my 3.2 hp mariner 2 stroke. Was pumping water ok but over heating. Ended up taking the head off and clearing the waterjacket around the cylinder block. The waterways were blocked with a thick waxy gunge which I realised was being picked up from the club flushing tank that had not been cleaned out for years. It has now!

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