Engine Temp Gauge pegged at High even when cold
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RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, Engine Temp Gauge pegged at High even when cold in Past Cadillac Vehicle Discussion; Hi all. Well, the 1968 Deville Convert arrived last night. Right at start, the Engine Temp gauge is pegged at ...
  1. #1
    jukelemon's Avatar
    jukelemon is offline Cadillac Owners Member
    Automobile(s): 1968 Deville Convertible
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    Engine Temp Gauge pegged at High even when cold

    Hi all.

    Well, the 1968 Deville Convert arrived last night.

    Right at start, the Engine Temp gauge is pegged at little under the H. Engine Temp warning light is on immediately after of course.

    It cannot be accurate considering the engine is cold. So I am thinking it is either 1- bad gauge or 2-a bad sending unit?

    I am assuming the Engine Temp warning light is hooked into the gauge so it makes sense it is on given that the temp starts at H when cold.

    Before I start digging in, just was wondering if anyone else has experienced this.

    Thank you.

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    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: Engine Temp Gauge pegged at High even when cold

    I've seen people mix up the heater fan enable switch with the temp sender many times. Have the heads been off or the engine out?

  4. #3
    nebulosity's Avatar
    nebulosity is offline Cadillac Owners Fanatic
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    Re: Engine Temp Gauge pegged at High even when cold

    Quote Originally Posted by jukelemon View Post
    Hi all.

    Well, the 1968 Deville Convert arrived last night.

    Right at start, the Engine Temp gauge is pegged at little under the H. Engine Temp warning light is on immediately after of course.

    It cannot be accurate considering the engine is cold. So I am thinking it is either 1- bad gauge or 2-a bad sending unit?

    I am assuming the Engine Temp warning light is hooked into the gauge so it makes sense it is on given that the temp starts at H when cold.

    Before I start digging in, just was wondering if anyone else has experienced this.

    Thank you.
    When my coolant sensor went bad, it showed a reading of 144C at my computer even when the engine was cold. Do you have a coolant temp sensor? Is that what your "sending unit" is?

  5. #4
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: Engine Temp Gauge pegged at High even when cold

    What does the gauge say when the car is in the on position but not actually running?
    How does the engine run? Is the gauge steady at the temp or does it jump a bit?
    The gauge reading high when the engine is cold and running is sometimes caused by a head gasket on it's way out. I would say that would be a worst case scenario though.

  6. #5
    jukelemon's Avatar
    jukelemon is offline Cadillac Owners Member
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    Re: Engine Temp Gauge pegged at High even when cold

    Hi all.

    It is always registering H so I don't think it is an engine failure. Seems like a sending unit issue to me.

    Let me be very specific. If it was 30 deg out and I went to start it, it would register H.

    It does not fluctuate at all.

    I have the FSM and it states a testing procedure for this condition. Either the engine temp sensor or the gauge is suspect. I just have to tear into the dash panel for the gauge.

    Thanks all.

  7. #6
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: Engine Temp Gauge pegged at High even when cold

    Unplug the sender before tearing into the dash. Easy first.

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