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Thread: Oldsmobile cooling issues!!

  1. #1
    Moderator vetteboy86's Avatar
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    May 2003
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    1986 Black "Indy 500 Pace car replica"

    Default Oldsmobile cooling issues!!

    So I talked my wife out of a big SUV and we ended up finding a used Honda Accord. Nice car. So with that said, I am going to keep her 95 olds Cutlass Supreme and drive it to and from work, over driving my truck. As you would expect, the fuel mileages is way better.

    Well anyways, I noticed if running a little warm on the gauge, or at least it looked warm. I know the analog gauge's sometimes are not linear. So with that being said, I started to look at the cooling system. To see if there were any issues.

    I first believed that the cooling fans were inoperable, because the gauge would read to the second tick mark, and they wouldn't turn on. I tested the fans, and they were good, I tested the relays, and the relay signals and everything checked out. So I just let the car idle in the driveway, and after 20 or so minutes of idle time the first cooling fan did turn on.

    So I then looked at the temperature switch. In this case, I thought it would be the same sender as the gauge, but it isn't. I pulled the cap, and the SES light came on. Plug back in SES light went off.

    So my questions are: Is there any accurate way to determine how hot the car is actually getting before the fan turns on? Is there any way to test the temp switch? I thought about grounding it to see if the fans would turn on, but wasn't sure.

    So now I think it is either a bad switch, or air is trapped in the cooling system, and the gauge is reading hotter than the car actually is.

    Sorry it's so long, but this is my new driver, and I know summer is coming!

    Mods to date:
    383 Stroker, Heads/cam/ intake, Ported Plenum, Ported and siamesed runners, Big Mouth Manifold with EGR delete, 52MM TB,TPIS Long Tube Headers, 3" exhaust, Dynomax UltraFlow Mufflers, Holley AFPR, MSD 6AL, 30# injectors,255 LPHWalbro fuel pump, Vortex Ram Air, MAT Relocation kit, TB Bypass,Heated 02,2400 RPM stall torque converter, Pioneer Head unit, Infinity speakers.

    Mods soon to come:
    Super Ram/Mini Ram?? 3.73 rear gears.

    Other vehicles:
    1973 Bucaneer Red Pontiac Trans Am 455 w/4sp
    1971 Starlite Black Pontiac Formula 455 auto w/air.
    2004 Victory Red Chevy Silverado Z71 5.3

  2. #2
    Technical Advisor c4c5specialist's Avatar
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    May 2001
    New Haven, Ct. USA
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    Nope, but someday.


    Hi there,
    The first thing is to understand that there is no switch, this is command controlled by the ECM
    Second, what engine do you have?
    Third, only TEch 2 data can effectively tell when the fans turn on.
    Turn on the AC to make sure they work.
    As long as the compressor is running, your fans should run also.
    GM World Class Certified Technician.
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  3. #3
    Member minifridge1138's Avatar
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    Feb 2007
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    1982 Black Fastback


    Buy an Infrared temp gun and measure the block where the radiator hose attaches (that is usually where the thermostat is). That is the only way to know how hot the engine is.

    You'll also see at what temp the fans come on. Listen to c4c5specialist about the AC. Several cars have an auxiliary AC fan that comes on with the compressor.

    Is the radiator full?

  4. #4
    Moderator vetteboy86's Avatar
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    1986 Black "Indy 500 Pace car replica"


    Paul, I did realize it isn't actually a switch, but I have heard it referred to this in the past. Any idea why??

    More importantly, neither of the two fans come on when the ac is on. I know the compressor actually is turning so it is engaged.

    I did replace the temp sender for the gauge which didn't change things. The cooling system is full, and there doesn't appear to be any trapped air as I have used the bleeders with no signs of escaping air.

    I am going to use an infrared thermometer to see what the temps actually are!

    However, now I am leaning towards maybe a thermostat issue?? I know it is opening because the upper radiator hose will get hot. Although maybe it is sticking and not opening all the way. Could this explain why during idle or cruise at low rpms the temp creeps up, but when I accelerate, or just rev the engine i will see it drop??

    I am thinking that the compressor switch, or the ecm signal to control the second fan may be faulty.

    Any more suggestions??

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