Thread: 32 ford coupe - AFCO radiator - Overflow level?

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Yes, both are under pressure. My tubular overflow, has a pressure cap on it. But it doesn't have anything in it ! I was going to put a cup full of radiator fluid in, and check it again, after it cools down - - - next time I go out. Its raining in So. Cal right now. Thanks again Dave and Jerry.

Originally Posted by Simi Mike

Yes, both are under pressure. My tubular overflow, has a pressure cap on it. But it doesn't have anything in it ! I was going to put a cup full of radiator fluid in, and check it again, after it cools down - - - next time I go out. Its raining in So. Cal right now. Thanks again Dave and Jerry.

Nope, that's what the second tube is for. Let's the pressure out! If it was a sealed container, nothing would be allowed in! The second tube should be within an inch or so of the top (generally..) Fluid any higher than that would come out and you'll know your system is overfull.

Originally Posted by Simi Mike

Yes, both are under pressure. My tubular overflow, has a pressure cap on it. But it doesn't have anything in it ! I was going to put a cup full of radiator fluid in, and check it again, after it cools down - - - next time I go out. Its raining in So. Cal right now. Thanks again Dave and Jerry.

I have the same overflow tank, but my overflow cap is not a pressure cap. Like Mike says, the vent lets any pressure out anyway, along with excess fluid. I also have a recovery pressure cap on the radiator, so it sucks back fluid to keep the system free of air. For what it's worth, I fill my radiator as much as possible, then fill the overflow to within about an inch of the overflow tube before going for a drive. After it cools down I check the overflow, and if there's fluid covering the inlet tube I fill it about 1/2 full. If it's empty I know that the radiator sucked in some air, so I fill it nearly to the top again before the next drive. Your cupful approach will work, but it may take you several trips of coming back to an empty tank to purge the air from your system.