check your bib cock on the bottom of the radiator. they are usually palstic and going in to an aluminum radiator when it gets cold often times the plastic will contract more than the aluminum and cause a leak, as a mechanic i hate that stop leek stuff, however pepper like T said doesn't usually cause much of a problem i have also seen an egg work, just crack it open in to the radiator the white will cook and fill in some small holes until you can fix it right the rest will get broken up and flushed out.

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