Overheats on the highway or at higher rpms for extened time
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Cadillac Allante Forum Discussion, Overheats on the highway or at higher rpms for extened time in Past Cadillac Vehicle Discussion; I have a 1990 Allante. It runs good and shifts good but when I take it on the highway or ...
  1. #1
    joetighe is offline Cadillac Owners Member
    Automobile(s): 1990 Cadillac Allante
    Join Date
    May 2013
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    20
    I have a 1990 Allante. It runs good and shifts good but when I take it on the highway or on really hot days if I am holding a higher rpm it overheats. Under normal 40MPH roads it doesn't get above the middle bar. I have checked the fans with the DIC and they both work. The coolant level is good. I'm not sure where to start, with the fan speed or the water pump? Any help would be great!

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  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
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    california
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    67
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    Re: Overheats on the highway or at higher rpms for extened time

    Classic symptom of a restricted, plugged radiator. What do you consider " overheating" Does it boil over, or just that the gauge goes past center?

  4. #3
    joetighe is offline Cadillac Owners Member
    Automobile(s): 1990 Cadillac Allante
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    Thread Starter
    It has never boiled over. The hottest it's ever gotten is second to last bar. Any way to test the radiator?

  5. #4
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
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    california
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    67
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    5,945

    Re: Overheats on the highway or at higher rpms for extened time

    First things to do are replace radiator cap with a DELCO brand one, then Burp the system to rule out trapped air in the system. THEN, take it to a radiator shop that has an infra red thermometer. They will test sections of the radiator for cooler areas. Cooler areas are blocked areas.

  6. #5
    smumfor's Avatar
    smumfor is offline Cadillac Owners Member
    Automobile(s): 89 Allante / 90 Allante
    Join Date
    Jun 2003
    Location
    Jacksonville, FL
    Posts
    19

    Re: Overheats on the highway or at higher rpms for extened time

    Has the car ever overheated that you know of.... I am thinking Thermostat ... but most likely I agree with carnut the Radiator is clogged.

  7. #6
    joetighe is offline Cadillac Owners Member
    Automobile(s): 1990 Cadillac Allante
    Join Date
    May 2013
    Posts
    20
    Thread Starter
    Thanks so much, I changed the thermostat when I bought the car because that was my first thought about the overheating. I will take it to a shop soon thanks!

  8. #7
    nbaum is offline Cadillac Owners Member
    Automobile(s): 1993 & 1992 Allante
    Join Date
    Oct 2013
    Posts
    39

    Re: Overheats on the highway or at higher rpms for extened time

    I would change the thermostat first. My 92 would run hot and then all of a sudden drop. New thermostat fixed it.

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