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Discussion Starter · #1 ·
I have 1972 Ford Thunderbird with the 7.0 429. The issue I’m having is after driving about 20-30 minutes and I park and turn the car off sometimes the coolant will come out the top of the radiator where the overflow tube is, there is no reservoir on the car. What is causing the coolant to get pushed out?
 

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HI as FoMOCo said thermo expansion.. when cold the coolant should be about 1" below the cap opening (right at where the cap opening starts).. The cap should be rated at 14 to 17 lbs.. as thermo expansion starts it also creates pressure.. if the cap does not hold the proper pressure 14 to 17 lbs. it well cause the loss of coolant every time you shut it off or even driving it. THAT IS ALSO WHY YOU DON'T REMOVE THE CAP WHEN HOT IT WELL SHOOT VERY HOT COOLANT UP INTO YOUR FACE.... Replace your cap or have it checked to see if it is holding pressure .. it should be marked on the cap ...
early 70's is when they started closed coolant systems.. with a recovery tank. with a recovery tank when it heats up and pushes coolant out it well be caught by the recovery tank and as it cools down it well be drawn back into the system with the vacuum created with cooling with no loss.

good luck take care be safe
tim
 

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If your car has a cross flow radiator there will be markings on the end tank, telling you the cold fill level. My 69 429 Mercury cross flow radiator had a cold fill level about 6" below the radiator cap.
You could add a recovery tank that would keep the cooling system air free and full all the time.

Richard
 

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Discussion Starter · #6 ·
HI as FoMOCo said thermo expansion.. when cold the coolant should be about 1" below the cap opening (right at where the cap opening starts).. The cap should be rated at 14 to 17 lbs.. as thermo expansion starts it also creates pressure.. if the cap does not hold the proper pressure 14 to 17 lbs. it well cause the loss of coolant every time you shut it off or even driving it. THAT IS ALSO WHY YOU DON'T REMOVE THE CAP WHEN HOT IT WELL SHOOT VERY HOT COOLANT UP INTO YOUR FACE.... Replace your cap or have it checked to see if it is holding pressure .. it should be marked on the cap ...
early 70's is when they started closed coolant systems.. with a recovery tank. with a recovery tank when it heats up and pushes coolant out it well be caught by the recovery tank and as it cools down it well be drawn back into the system with the vacuum created with cooling with no loss.

good luck take care be safe
tim
I put a small universal reservoir on it and replaced the radiator cap. Once it cooled down coolant did go back into the radiator and I just drove it 25 minutes to work and I could see it going back into the reservoir when I turned the car off. But before I put the reservoir on I did notice it is quite bubbly when it did come out the overflow tube. Is it normal to be bubbly? It looked kinda like soapy water consistency. Once it cooled down and I opened the radiator it was normal. When it was going back into the reservoir after the 25 minutes it also had a small layer of bubbles on top and the rest regular liquid?
 
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