Misc Stories and Removing that stuck temperature sensor...

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  • marthur
    Afourian MVP
    • Dec 2004
    • 844

    Misc Stories and Removing that stuck temperature sensor...

    So, I am in the North Channel of Lake Huron cruising and have had the first engine issues in over 200 hours.

    Here is the list: A bizarre failure of the MMI water pump shaft--Don stood behind his product even though there was no reasonable expectation of a warranty. That is the reason all of my A4 business goes through Moyer Marine--customer service that far exceeds expectations. Good thing I carry a spare pump too!

    Second: charging batteries. I thought is was a bad alternator, but trouble shooting ID's an old wire with excessive resistance, I replaced the wire and significantly shortened it. In fact, I bypassed my ammeter because I plan to fill that spot in the panel with a tachometer. Batteries are full and the only question is "Santa are you listening to the part about the tachometer?"

    Third: temperature sensor failed. The only problem with that was removing it. It was STUCK. As in there is stuck, there is permanently fixed in place and then there was the brass temperature sensor.

    However, with a little thought it came out. Here is what I did: First I wire brushed it and applied penetrating oil. Then I removed the thermostat and applied penetrating oil to the INSIDE threads of the sensor. It was still pretty stuck and my flat sided wrench was beginning to damage the hex head so I added cold and a better tool to the problem.

    Ordinarily I go for heat in a big way, but brass has a higher coefficient of expansion (and that also means contraction) than iron. So I iced the sensor down knowing that it would shrink more than the iron block (which was not iced or heated).

    Then I used a six sided half inch drive socket and breaker bar and went for it. My advice is not to attack one of these without a six sided socket, the brass is too soft to handle any other tool. It took some effort (as in two hands, feet braced and put all you got into it) but it came out with no damage. Woohoo! Time for a cold one. Good thing I had ice on hand

    The funny thing is that I like working on the motor so much I almost look forward to these little things...
    Last edited by marthur; 07-09-2012, 02:04 PM.
    Mike
  • sastanley
    Afourian MVP
    • Sep 2008
    • 7030

    #2
    marthur, how did you get ice just on the sensor?

    I look forward to 'working on the engine' sessions as well. Especially when something actually goes as planned and you don't break anything along the way...
    -Shawn
    "Holiday" - '89 Alura 35 #109
    "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
    sigpic

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    • marthur
      Afourian MVP
      • Dec 2004
      • 844

      #3
      To ice just the sensor, I took a small chunk of ice, like a really big cube, and pressed it against the sensor (which sticks out of the head). The engine was probably 100 degrees F because the day was hot, so that sensor melted its way into the ice cube. When a sufficiently large "cave" was melted, I was able to literally hang the ice cube on the sensor. I left it that way for about 30 minutes, replacing the ice once. That coupled with the different rates of expansion was just enough to make a difference getting that beast out.
      Mike

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      • joe_db
        Afourian MVP
        • May 2009
        • 4527

        #4
        I did it using an impact socket and a breaker bar. Sockets designed for impact wrenches seem both stronger and machined to better tolerances and thus less likely to round off the sensor.
        Joe Della Barba
        Coquina
        C&C 35 MK I
        Maryland USA

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        • edwardc
          Afourian MVP
          • Aug 2009
          • 2511

          #5
          Originally posted by joe_db View Post
          I did it using an impact socket and a breaker bar. Sockets designed for impact wrenches seem both stronger and machined to better tolerances and thus less likely to round off the sensor.
          I did exactly the same thing.
          @(^.^)@ Ed
          1977 Pearson P-323 "Dolce Vita"
          with rebuilt Atomic-4

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          • marthur
            Afourian MVP
            • Dec 2004
            • 844

            #6
            I didn't have an impact socket here but I did have a six sided socket and breaker bar. That and my gorilla strength
            Mike

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