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  1. #1
    Member
    Join Date
    Oct 2015
    Location
    Granbury Texas
    Posts
    8

    Is it overhearing

    I have a 200L carb serial# OT630748 Merc outboard
    I recently installed a temp gauge I threaded the sending unit in the threaded port
    just under the #4 spark plug my factory overheat is still hooked up and is working like it always has
    but the gauge is reading seems high from what I have read
    At idle warmed up it reads 175 with 3 psi water pressure
    at 3000 rpm its reading 185 with 7 psi water pressure
    at full throttle its at 200 with 12 psi
    Being this is head temperature and not water temperature is this to hot and do I have the
    sending unit in the right place
    Any help very much appreciated Thank you

  2. Member
    Join Date
    Mar 2012
    Location
    Pelham, GA
    Posts
    2,004
    #2
    I have the same set up and the head temps are generally hot. My gauge doesn’t have degrees on it but at idle it’s atbout 3/4 on the gauge and running it’s just under the last mark. To verify temps use an IR thermometer and read temp just behind thermostat on top of head. Should be around 143-150 when warm at idle. Thermostats should open around 143. The alarm doesn’t go off until around 242.
    Mercury 2002 200hp Carbed Saltwater
    OT566776
    2002 Cape Horn 22' Bay

  3. Member
    Join Date
    Oct 2015
    Location
    Granbury Texas
    Posts
    8
    #3
    Thank you so much for the response
    The stock overheat alarm is working just a little paranoid after overhaul last year

  4. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
    Posts
    13,941
    #4
    should be place for temp sensor between 2 and 4 not below 4 ,must be aftermarket sender, really need to get wpsi up to 15, and post in v6 section one down
    .................................................. ...the scariest thing in life is the unknown ...................................