temperature gauge going all the way up when the car is not running

Discussion in 'General Motoring' started by rynniki, Jul 22, 2005.

  1. rynniki

    rynniki Guest

    my gauge was all the way up to hot then it would drop all the way to
    normal, the car was not overheating it seemed like the guage was stuck and
    it would go all the way up when the car was on but not running ,so they
    changed my temperature sensor,it was fine for 2 days then it did it
    again,it shot up when i started the car and after the car was runnng for 3
    monutes or so it dropped to normal. what could be wrong??? could it be my
    gauge? water pump and radiator and thermostat is fine..thanks guys
    rynniki, Jul 22, 2005
  2. To clarify - the car could be sitting overnight, then as soon as you start
    it the guage is at max but comes down as the car warms up? Also, when it
    drops is it gradual or sudden? Finally, what model and year is this?

    If that's the case (pretty much regardless of whether it drops gradually or
    suddenly) it almost has to be the guage. Some guages - don't know for sure
    about yours - are balanced coil types. Instead of the guage operating
    against a spring the returning force is another coil energized with the same
    voltage as the voltage that feeds the sensor, so the guage isn't voltage
    sensitive. Balanced coil types can do that if the ground is missing from the
    guage or if something is wrong with the balancing coil. If the shop has a
    sensor simulator (a variable resistor or a "decade box") they can see if the
    guage is being wacky at all temperatures or only when cold.

    Working on guages isn't cheap because of the difficulty getting to it.
    However, if the guage isn't reliable at normal and high temperatures you may
    not have a choice. Not knowing if your engine is starting to overheat can
    lead to some shocking expenses.

    Michael Pardee, Jul 22, 2005
  3. rynniki

    rynniki Guest

    no its not the reservoir fluctuates
    rynniki, Jul 22, 2005
  4. rynniki

    rynniki Guest

    1994 honda civic ,it does it when siiting overnight and also after i get
    off work it did it,but this morning i checked it and it didnt do it.and
    its a sudden dropping not gradual.but even if i dont start the car and
    just turn the key so the radio and all come on it shoots up and then drops
    to normal
    rynniki, Jul 22, 2005
  5. If the guage works when it isn't being weird - reading cold at first then
    following the engine as it warms up - you may be best to leave it alone.
    Intermittents are notoriously hard to fix and I'm sure this will be
    something in the guage. After all, there really isn't anything but the
    sensor and the guage (unless something really odd with the instrument
    voltage regulator is doing that) and the sensor has been replaced. The guage
    is a pain to get to. It won't misbehave predictably enough to be sure it's
    fixed until you've had the car back a while. Trying something else means
    going back into the instrument cluster, and even replacing the guage is not
    a guaranteed fix because it could be a ground problem. Maybe this is
    something you will need to live with until it gets intolerable.

    Michael Pardee, Jul 22, 2005
  6. rynniki

    DGB Guest

    My wife's 95 Civic's temp gauge died a while back and I still haven't been
    able to locate the prob with it. Two days ago however the check engine
    light came on and then went off again and the speedo then died and came back
    about 10 minutes later.

    DGB, Jul 22, 2005
  7. rynniki

    Jim Yanik Guest

    Bad electrical grounds?
    Jim Yanik, Jul 22, 2005
  8. rynniki

    MLD Guest

    It could very well be a sticky thermostat. Two approaches: 1st: Take the
    radiator cap off. Let the engine warm up; you can tell when the thermostat
    opens because the hose feeding the radiator will suddenly get very hot. You
    need a thermometer that will give you a good reading in the 200 to 250F
    range. When the hose gets hot have the thermometer in the neck of the
    radiator and note the temperature. Well over the stat opening temp would
    place a lot of suspicion on the stat. 2nd: Just replace the stat if you
    MLD, Jul 26, 2005
  9. Although in another post the OP mentioned it would do it the moment the key
    was turned on in the morning, so it has to be a false reading.

    Michael Pardee, Jul 27, 2005
  10. rynniki

    rynniki Guest

    thanks guys for your help i will keep an eye on it
    rynniki, Jul 28, 2005
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