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  1. #1

    Default 1975 Evinrude 70 hp Outboard thermostat ?

    I have a 1975 70 hp outboard that starts like a champ and appears to have plenty of water coming out of the lower unit shifting is very smooth. I am afraid the head is getting too hot and am not sure how to tell if it is or not. After just a few minutes of running the outside appears to be rather hot and the water coming out of the lower unit is not barely luke warm. I would rather not replace a water pump if it is operational but how do you really know?

  2. #2
    Supreme Mariner Joe Reeves's Avatar
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    Default Re: 1975 Evinrude 70 hp Outboard thermostat ?

    Test to see if the overheat warning horn is in effect. With the Key in the ON position, ground the TAN wire that is leading out of the cylinder head. The warning horn should sound.

    If the engine overheats, the warning horn would sound before any damage can occur.

  3. #3
    Supreme Mariner kenmyfam's Avatar
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    Default Re: 1975 Evinrude 70 hp Outboard thermostat ?

    Quote Originally Posted by G_dub66 View Post
    I have a 1975 70 hp outboard that starts like a champ and appears to have plenty of water coming out of the lower unit shifting is very smooth. I am afraid the head is getting too hot and am not sure how to tell if it is or not. After just a few minutes of running the outside appears to be rather hot and the water coming out of the lower unit is not barely luke warm. I would rather not replace a water pump if it is operational but how do you really know?
    How long can you keep your hand on the head when it is "hot"
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  4. #4

    Default Re: 1975 Evinrude 70 hp Outboard thermostat ?

    About 5-7 seconds but I am not sure I have left it on long enough to have the thermostat kick in.

  5. #5
    Supreme Mariner kenmyfam's Avatar
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    Default Re: 1975 Evinrude 70 hp Outboard thermostat ?

    Quote Originally Posted by G_dub66 View Post
    About 5-7 seconds but I am not sure I have left it on long enough to have the thermostat kick in.
    That sounds O.K. but how long have you run it before you check. I run at idle for 10 minutes at least before I check.
    Marada 2100 Executive Series, 5 Litre V8 with Mercruiser Alpha 1 outdrive. 2007 K-Z Spree 260 RBH, all = a whole lot of family fun !!!!

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