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Results 1 to 13 of 13
  1. #1
    Join Date
    Oct 2009
    Location
    Slidell, La.,
    Posts
    27

    Default Where is the thermostat? 1983 Mariner 50 HP

    1983 Mariner 50HP serial number B13 thats all I have. Does this motor have a thermostat and if it does can you tell me where it is? Motor has a constant alarm going off at about 25% throttle and I m thinking it is the thermostat over heating.

  2. #2
    Join Date
    May 2007
    Location
    Inverary, Ontario, Canada - The Great White North Eh!
    Posts
    9,127

    Default Re: Where is the thermostat?

    How many cylinders does this have?

    There was never a 50 horse Yamaha/Mariner, so you must have one of the Merc/Mariner models.

    The 1983 model was a 4 cylinder but your bit of serial number tends to indicate a 1986 3 cylinder model (unless that B is actually a 6 - 613 would be a start serial for one built in 1982).

    Looking at the parts lists, neither had a thermostat (not uncommon on older models) but the 3 cylinder did have a temp sensor on the waterjacket cover (neither model had a "head" in the traditional sense).

  3. #3
    Join Date
    Oct 2009
    Location
    Slidell, La.,
    Posts
    27

    Default Re: Where is the thermostat?

    Thank you for the info.

    It is a three cyl. It has a Mariner cover, if that means anything. I was also looking at a parts list and didn t see a thermostat.

  4. #4
    Join Date
    Sep 2010
    Location
    louisiana
    Posts
    76

    Default Re: Where is the thermostat?

    You didn't say anything about any maintenance to your motor. Since it seems to be getting hot, did you give any thought to the water pump? Has it been changed recently?. If it has, it maybe an electrical problem causing the alarm. I don't know what the water discharge temp should be, but you could check that to see if the motor is really running hot. Good Luck...BF

  5. #5

    Default Re: Where is the thermostat?

    Quote Originally Posted by galamb View Post
    How many cylinders does this have?

    There was never a 50 horse Yamaha/Mariner, so you must have one of the Merc/Mariner models.

    The 1983 model was a 4 cylinder but your bit of serial number tends to indicate a 1986 3 cylinder model (unless that B is actually a 6 - 613 would be a start serial for one built in 1982).

    Looking at the parts lists, neither had a thermostat (not uncommon on older models) but the 3 cylinder did have a temp sensor on the waterjacket cover (neither model had a "head" in the traditional sense).

    Reviving an older thread here.
    I have the Mariner 50hp 2stroke inline 4 with SN 6453200. Im guessing its a 1983 model but I may be wrong.
    I dont see any temp sensor on this engine but it does have a bolt on the head that gives me access to the water that cools the head. Do I install a temp sensor in here? Where can I get one from?

    Thanks!

  6. #6
    Join Date
    May 2007
    Location
    Inverary, Ontario, Canada - The Great White North Eh!
    Posts
    9,127

    Default Re: Where is the thermostat? 1983 Mariner 50HP

    That serial makes it a 1984 model.

    This model did not have a temp sensor as "standard" kit and I am not quite sure what (bolt) you are referring to. There is a plug on the water jacket cover (just above and left of the top spark plug) - if that's what you are referring to you could install a temp sensor there. If it is that "plug", simply remove it and take it with you to any marine dealer and ask for a temp sensor with the same thread size - or if you need the gauge as well I believe that Teleflex (and probably Faria) will sell a kit (sensor/gauge) for between 30-50 bucks...
    Graham

    A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

  7. #7

    Default Re: Where is the thermostat? 1983 Mariner 50HP

    Thanks for the quick response galamb.
    The bolt im referring to is closer to the middle two cylinders. Its plugging up a hole that goes where the water flows to cool the head. I know this because I changed the water jacket cover gasket recently and its just a hole drilled straight through with a bolt in it. Almost like an inspection hole.

    However, I also have another hold with thread in it closer to the top cylinder with no bolt in it. It also doesnt go all the way through the water jacket cover. Im assuming this is where the sensor will go?

    When I bought the boat it already had a temp gauge beside the tacho but it isnt wired up. So im hoping it will be as simple as getting the sensor, screwing it in the water jacket cover and connecting it to the (powered) gauge. Does this sound right to you?
    Finally, is this sensor bolt a standard sized thread? Any brand will do? Or does it have to be a specific Mariner 1984 4cyl 50hp one?

    Thanks again for your help!

  8. #8
    Join Date
    May 2007
    Location
    Inverary, Ontario, Canada - The Great White North Eh!
    Posts
    9,127

    Default Re: Where is the thermostat? 1983 Mariner 50HP

    You can put the sensor at any convenient spot on the head (these are headless but you get what I mean).

    99% of the sensors (that hook to the gauge, not an alarm system) are a standard size (can't remember off the top of my head what it is but know that my Merc and OMC sensors are interchangable).

    And yes, it will be as simple as you think - screw it in, hook up the wire and you will be good to go.
    Graham

    A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

  9. #9

    Default Re: Where is the thermostat? 1983 Mariner 50HP

    Thanks very much for yoUr help mate. Much apprEciated

  10. #10

    Default Re: Where is the thermostat? 1983 Mariner 50HP

    Im trying to find the right part I need but am having some trouble finding a proper match.
    Can someone please clarify which temp sensor I need to get that fits on to the head?

    So far im thinking this is what I need: http://www.go2marine.com/product.do?no=158431F

    But I also found these that dont have pics but the description matches.
    http://www.go2marine.com/product.do?no=90852F
    http://www.go2marine.com/product.do?no=165690F

    Can anyone shed some light on this please? Id like to pick one up soon.

    Thanks for your help.

  11. #11

    Default Re: Where is the thermostat? 1983 Mariner 50HP

    I have a 1984 Mercury outboard 50hp... would it be ok to plug the sensor hole and install one in another location.

  12. #12

    Default Re: Where is the thermostat? 1983 Mariner 50 HP

    Can anybody tell me the very best way to clean the cover and around the plugs on cylinder head before putting the new gasket on...it's a 1984 50hp Mercury outboard...this will be the third time doing it... please help.

  13. #13
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,554

    Default Re: Where is the thermostat? 1983 Mariner 50 HP

    First of all, you need the 'glass plate' the cover to make it flat--then tend to warp with the heat. To do this, you'll need a large piece of 80 grit sandpaper taped to a window. (Use use two pieces of sandpaper held at their sides with duct tape.) A thin spray of paint on the cover will show you where the high and low spots are. And don't shove the cover so it digs in on one end--allow it float across the sandpaper.

    With that done, used a new gasket with plenty of silicone around the plug holes on both sides of the gasket. And make sure the block is spotlessly clean where the gasket touches.

    Jeff
    Last edited by fastjeff; 01-04-2018 at 08:40 AM.

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