C3 Overheats

My 80 coupe, auto overheats if I exceed 55 on the highway. Around town, it's fine. Any ideas?
TIA Pappy

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My 75 did this when I first got it and a close inspection revealed that it was missing a piece of shroud by the radiator. When that got replaced, the problem was resolved. Also, make sure the air dam is intact. - Bill

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support ....made a huge difference in one of my C3's ...also the air dam on the bottom facia of the car is REQUIRED... remove it and you will see the temps jump pretty quickly...
Its early and the brain is still not up to speed...But I have seen a stuck open Thermostat cause this .... as well as no thermostat at all... if the volume of water running thru your radiatoris too high it will not cool simply because it is not in the radiator long enough...?
Bob G. .
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wrote:

air pocket that would cause the pump to cavitate. It's fairly common to get the air pocket if you don't fill the system slowly check it running while it's sitting. If you see the level go significantly up and down in the radiator, you have an air pocket.
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Missing air dam or shroud parts... or No T-Stat installed. Yada yada
Pappy wrote:

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Ric Seyler
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