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  1. #1
    Join Date
    Mar 2010
    Location
    essex uk
    Posts
    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
    Location
    South
    Posts
    12,762

    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
    Join Date
    Jan 2010
    Location
    South Devon
    Posts
    70

    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
    Join Date
    Feb 2007
    Location
    Poole, Dorset
    Posts
    588

    Default

    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
    Location
    essex uk
    Posts
    68

    Default

    Hi can you explaine where the stat is please

  6. #6
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    33,784

    Default

    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
    Location
    essex uk
    Posts
    68

    Default

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

  8. #8
    Join Date
    Jan 2011
    Location
    No fixed abode
    Posts
    1,470

    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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