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Thread: Over - Cooling

  1. #1
    Join Date
    Dec 2014
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    Sherborne, Dorset
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    99

    Over - Cooling

    Hi all.

    Can't get my head around this one so thought I would ask for opinions please. I'm running a 351 Windsor. Recently drained and flushed the cooling system, new thermostat, new hoses. No leaks . Starts on the button and warms up nice and quickly and the thermostat opens at about the right temperature - circa 82 degrees. Around town it stays around that temperature and, if I get stuck in traffic it nudges up a bit but the fans kick in and keep it all under control. Heater works fine but is the standard Spitfire matrix so not huge.

    Thing is, when I get on to the open road and start cruising at 70-80 ish, the temp gauge slowly drops to around 50/60 degrees and stays there until I start pootling again . I know running an engine too cool is not good so am keen to work out why it doesn't stay hot on a fast cruise.

    Anyone come across this before?

    Cheers,

    Bill
    Bill

    Crendon Chassis No:13

  2. #2
    Join Date
    Sep 2007
    Location
    Hilperton,Wiltshire
    Posts
    2,620
    What was it like before? All that cold air blowing over the rad and around engine will keep it cool.


    Andy

  3. #3
    Join Date
    Feb 2007
    Location
    West Sussex
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    9,170
    are you running mechanical or electrical gauges? the electrical ones are only an indicator of 'some heat'.
    Crendon Chassis No.49
    Huddart FE428 + toploader

    Not listed in the Shelby Register.

  4. #4
    Join Date
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    on the edge...almost falling off
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    At that temp the thermostat would be closed so no coolant flowing through the radiator. Can you get to those conditions then stop the car and quickly check the top hose for temp? If its hot then the thermostat is working, the coolant is at the correct temp but possibly air flow on the coolant sensor is fooling it? just a thought
    BIG TONE


    Mercedes SL owner, definitely NOT a kitcar owner like you lot!


  5. #5
    Join Date
    Sep 2009
    Location
    Buckingham
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    Same issue with my SBC always been the same. Checked everything all the usual culprits. Just about got it right for summer use by blocking off the Rad by 60%. Run like this all summer and brings the temp up as it should,even on that really hot day back in August all was kept under control by the fan.
    I have noticed in the past few weeks that due to the drop in temp it does run a bit low on the open road.
    As Tone says,it may be the sensor is in a cold spot, that was also a suggestion by my engine builder.

    Rog
    AK 427 SC now sold. New ride is a 57 Chevy Bel Air Big Block 454

  6. #6
    Join Date
    Dec 2014
    Location
    Sherborne, Dorset
    Posts
    99
    Thanks guys.

    It was the same before Andy although I suspect it is more efficient now 'cos there was quite a lot of crud came out when I flushed it.

    Running electrical temp gauge Kevin. Did wonder if I should change it to mechanical although it seems to register approximately the right temp at the point when the thermostat first opens but I know they're not particularly accurate across the range.

    Good idea Tone - I'll give that a try.

    The sender is on top of the inlet manifold and very close to the bonnet scoop come to think of it so could be in a cold spot as you say.

    Thanks again.

    Bill
    Bill

    Crendon Chassis No:13

  7. #7
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
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    3,759
    Have you got an oil cooler fitted?

  8. #8
    Join Date
    Feb 2007
    Location
    West Sussex
    Posts
    9,170
    suggest you wrap the sensor up in something heatproof and see if that changes anything.
    Crendon Chassis No.49
    Huddart FE428 + toploader

    Not listed in the Shelby Register.

  9. #9
    Join Date
    Dec 2004
    Location
    Staines Middlesex / Abu Dhabi
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    1,083
    Would suggest that as long as the thermostat is opening correctly, maybe change it for one that runs hotter ?
    Also check that fan switches operate at required temp. When running cooler is the fan running? , that would suggest the temp sender to the guage is incorrect low ?
    Just sounds like system is efficient after the changes performed.
    Chris Lutman -427SC Coupe / MG Tojeiro "LOY" replica

  10. #10
    Join Date
    Dec 2014
    Location
    Sherborne, Dorset
    Posts
    99
    I don't have an oil cooler and the rad fans cycle on and off at about the right temps so suspect it must be something to do with the gauge or sender. Will fiddle with both and see what happens.

    Thanks all.

    Bill
    Bill

    Crendon Chassis No:13

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