Overheats on the highway or at higher rpms for extened time
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 9 of 9
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 and a Black 2005 Cadillac Escalade ESV
    Join Date
    May 2013
    Location
    New Hampshire
    Posts
    23
    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!


  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    68
    Posts
    6,480

    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 and a Black 2005 Cadillac Escalade ESV
    Join Date
    May 2013
    Location
    New Hampshire
    Posts
    23
    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
    Join Date
    Feb 2003
    Location
    california
    Age
    68
    Posts
    6,480

    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
    21

    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 and a Black 2005 Cadillac Escalade ESV
    Join Date
    May 2013
    Location
    New Hampshire
    Posts
    23
    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
    40

    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.

  9. #8
    gdled is offline Cadillac Owners Member
    Automobile(s): '93 Allante
    Join Date
    Nov 2014
    Age
    75
    Posts
    7

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

    Since pressurized water boils at a higher temperature an old radiator cap that won't hold pressure can cause the exact symptoms. A quick visual check is to see if the rubber gasket has spread out beyond the edge of the spring. You can compare new and old caps to see. But caps are so cheap, I'd do that first. Also, check your coolant viability. If you've been adding water to your cooling system, quit it, you are lowering the boiling point. Only add Delco coolant, and don't forget the GM coolant pellets for aluminum blocks....Also, consider flushing the system and refilling with the required coolant. And the pellets, don't forget the pellets...

  10. #9
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    68
    Posts
    6,480

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

    Old thread! In my opinion, adding the pellets this late in the game only helps plug up the heater core and radiator. The pellets were invented and recommended to stop porosity leaks in the aluminum blocks, nothing else. Since the last posting back in July of 2014, nothings been updated. Another case of getting info then disappearing.

  11. Remove Advertisements
    Cadillac Forums
    Advertisements
     

+ Reply to Thread
Gear in this thread - Powered by O'Reilly Auto Parts

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

What Cadillac(s) do you own? (Or type NONE)

Please select your insurance company (Optional)

Your date of birth and age are displayed in several places on the forum. Only the administrator will have access to your date of birth should you choose to hide it via the privacy option below.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts