Carefully fill up the plastic tank, put the lid back on it, start the engine, and then go over all of the coolant lines with a paper towel. It is possible you have a crack in the plastic coolant tank or a leak in the line going from the tank to the radiator. Be careful not to overtighten the clamps on the coolant lines where they attach to the radiator - if they are not leaking, don't tighten them.
If your paper towels remain dry, check the inside of the car under the dash. Usually, if there is a leak on the inside, you will smell it first when the heat is on.
Good comedians never stay on one subject for a very long time, so don't spend all of your worries on the radiator itself :)

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98 V70Rawd(101Kmi), 95 854T(85K mi), 88 245(165K mi)