66 coronet coolant overflow

NorthOfForty said:

Could still be the thermostat possible. If it opens properly operating temp would be normal. But if it stays partially open hot water could go back into rad or expansion tank. But I wouldn't think it would happen as soon as u turn car off. Recovery tank would help but also might mask another problem. But if it works it's the way to go

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oldbee said:

Original downflow rad.? Maybe level is too high?

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coloradodave said:

Take your radiator cap to a parts store and have them do a pressure check with a Stant tester. It may just to be replaced. As was said, the level in the radiator, when cool, needs to be +- 1.5" down to allow for expansion of the coolant when hot.
Coolant recovery is the best way to go as it purges all the air from the system, which reduces corrosion.

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coloradodave said:

Take your radiator cap to a parts store and have them do a pressure check with a Stant tester. It may just to be replaced. As was said, the level in the radiator, when cool, needs to be +- 1.5" down to allow for expansion of the coolant when hot.
Coolant recovery is the best way to go as it purges all the air from the system, which reduces corrosion.

Click to expand...

coloradodave said:

Take your radiator cap to a parts store and have them do a pressure check with a Stant tester. It may just to be replaced. As was said, the level in the radiator, when cool, needs to be +- 1.5" down to allow for expansion of the coolant when hot.
Coolant recovery is the best way to go as it purges all the air from the system, which reduces corrosion.

Click to expand...

PRND21 said:

With a recovery tank, you will also need a radiator cap for a sealed system. If not, it will suck air back into the radiator as it cools.

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Johnpat said:

Agree with radiator cap problem

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PRND21 said:

With a recovery tank, you will also need a radiator cap for a sealed system. If not, it will suck air back into the radiator as it cools.

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George Warmouth said:

Hello my 66 coronet with a 1969 440 runs about 190 to 205 on very hot days not all that bad of temps. Just started yesterday to push coolant out the over flow when I turn the car off. What might be causing this. Never did this before. Ordered a coolant recovery tank. The car was done without one.

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Ranger16 said:

When you shut down, obviously the cooling system does as well, so the engine has no way to dissipate the heat. It's called "after boil". If you have an expansion tank on top of the radiator and don't leave room for expansion, it WILL puke coolant out until it makes enough room for expansion. That then would become your MAX coolant level.

If it had never done this before, I would ask if you just serviced or filled the cooling system (perhaps too much?).
If not, then something has changed and a recovery tank might just be a bandaid.

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