72 Fury 360 Radiator Cap -- vents coolant -- is this correct?


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FCBO Gold Member
Sep 17, 2018
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Orange County California
I noticed the overflow port on my radiator seeps coolant. So I bought a cap part # 7816. I did a bunch of work including freeze plugs and trans rebuild. Filled the radiator with coolant (yes, I flushed the system first) to the top of the radiator and once I confirmed a good flow I put the cap on and it seeps coolant from the overflow port. I am not sure if it is just "finding it's level" or if I have a problem. I noticed that some of the replacement caps have no pressure-release device but the one with the red relief doo-hickey is usually the only one in stock.

My car does not have an overflow tank and looks like it never did. I bought a universal one but don't know if I should install it. Wisdom please?
If you fill it to the neck it will seek it's own level. ^^^^^^^^^^^^^^^^ Yep 1" below is where it needs to be. There needs room in the top tank for it to expand and the level to rise. You obviously don't have a overflow reservoir.
As said, it should be down a little, but I always fill it and let it find its own level.

I have added an overflow can, mostly because I don't want my dog slurping up the anti-freeze.
I believe that 1972 should have had a factory coolant recovery tank on it. Usually right beside the radiator cap. In that blank space where the a/c lines come through the core support, which is where it is on our '72 Newport.

The main difference between the earlier coolant recovery radiator caps and the normal ones was a fiber gasket in addition to the normal metal seal. The better caps had a stainless steel gasket rather than a "metal" one. Later ones deleted the fiber gasket, it seemed. The other difference is a "dangler" in the middle of the cap, on the bottom of the rubber seal. That allows coolant to go back into the radiator when the system is not pressurized, but limit the outflow of coolant only when the system's pressure is exceeded.

The radiators did not change when coolant recovery was added. With no jug attached to the radiator coolant exit in the filler neck, as noted, about 1" down for the cold/ambient coolant level. Past that, it will find it's level. Check the level ONLY when cold!

The "release" lever radiator caps are generally not for coolant recovery systems. Some liked those caps to check the coolant level with the engine hot. Only thing is that in doing so, some coolant is usually lost, plus making a mess. DO get a piece of rubber hose to put on that outlet tube, so exiting coolant can go to the ground. There should be a clip on the side of the radiator to hold it.

Adding a coolant recovery jug where one is not already can be a bit tricky. The jug needs to be below the level of the radiator cap, with all tubing entering the jug from the bottom. The whole idea of the jug is to keep the radiator completely full at all times, using its coolant/cooling capacity to the max, rather than not.

Worst case scenario for where you are now, just add a rubber tube for the overflow to go to under the car rather than not. Then, when you are comfortable with how things work, put a non-lever cap on the radiator, if desired.

Take care,
72 was a transition year, some cars had overflow tanks but most did not, two different radiator caps were used depending on which you had, here is a photo of my 72 Polara with overflow tank and correct one year only cap.