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Coolant Temp Gauge Headaches

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    Coolant Temp Gauge Headaches

    86 325 w/ 64k miles.

    Car runs great and does not over heat but the coolant temp gauge does not work correctly.

    I have cleaned the posts and tightened the nut on the back of the cluster. I have also 'built up' with some solder on the board since it was a little worn out. I have also replaced the temp gauge with another used unit but still haven't gained on it.

    SI batteries have been replaced and I believe thats where the problem is. Prior to the new batteries I had a erratic tach and MPG gauge BUT a WORKING coolant temp gauge.

    I don't think the problem is at the thremo since it was working prior to the SI battery replacement.

    Hints or info on tackling this?
    86 325
    02 C5 Z06
    02 Z/28 - DD

    #2
    Check the brown temp sensor on your thermostatoc valve
    "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

    1987 E30 3L Turbo Stroker Das Beast
    2002 E39 M5

    Comment


      #3
      Originally posted by dvallis View Post
      Check the brown temp sensor on your thermostatoc valve
      What am I checking for? Also which plug on the thermo is responsible for sending the the temp to the guage? There are 4 different plugs. I know the very forward one messes with how the car runs/idles because if you unplug it, it will stumble badly.
      86 325
      02 C5 Z06
      02 Z/28 - DD

      Comment


        #4
        Figured it out, did a jumper and deleted the SI board entirely. So far no problems doing so..
        86 325
        02 C5 Z06
        02 Z/28 - DD

        Comment


          #5
          Could you share what you jumper'ed.
          1990 325i
          2004 330i Individual 6-speed
          sigpic


          Comment


            #6
            Originally posted by icewhite View Post
            could you share what you jumper'ed.
            x2
            20% Accurate

            Morty: Well Summer maybe people that create things aren’t concerned with your delicate sensibilities you know? Maybe the species that communicate with each other through a filter of your comfort are less evolved that the ones that just communicate? Maybe your problems are your own to deal with and maybe the public giving a shit about your feelings is a one way ticket to extinction.

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              #7
              I'm going to be doing it this weekend, and will post a pic/write up if OP hasn't.
              1985 325e Sedan, 1986 325e Sedan, 2006 BMW X5, 2012 M3 Sedan, 2013 135is, 2017 M3 Sedan ZCP Competition

              Comment


                #8
                Just ended up having to replace the entire SI board with a spare I had.

                Si board was failing, causing the temp gauge to read incorrectly. No new gauge, cleaning, etc would fix it, it was the si board itself, with Bavrest's stamp of approval.
                1990 Brilliantrot 325iS Build Thread
                1989 Zinnoberrot M3 Build Thread

                Comment


                  #9
                  if you google, there is a write up with pics on what to jumper for certain gage clusters. I think only the early ones can be jumpered but tis been about 12 years since I did one. it used to be on e30tech because I did pics when I did my 84's si board delete

                  Comment


                    #10
                    All,

                    For whatever reason I don't notifications when people respond to my threads or posts, so sorry for the ultra late response.

                    As superj said, there is a google image out there. I couldn't find the write up. But I've had this jumper wire soldered in place since I posted about it. Temps are normal and I've confirmed by checking with a laser temp gun and closely watch my temps. Going down hill coasting, it will fall. Cold icey weather, slower getting to temp vs a hot summer day.


                    Here is the image from google, like I said I can't find the write up. My car is 1986 325 auto and the mod worked. I don't know which years are different or not so I can't help there.
                    Last edited by Z06&E30; 03-30-2018, 06:05 PM.
                    86 325
                    02 C5 Z06
                    02 Z/28 - DD

                    Comment


                      #11
                      I did the same jumper on my car.

                      The little "U" is the jumper. Ignore the skinny red one going upwards bcause that is a repair for a failed circuit

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