Awhile back I had a woman traveling through to stop at the shop.
Her radiator, the one in her car, had a leak.
It was a small leak but she had lost a lot of water, in the car radiator.
Now, as I'm not a radiator repair shop, and the nearest one was 20 miles, in the opposite direction, I did what I do to my old 8N Ford tractor radiator.
I put a small can of black pepper in it. Yeah, I did! No sugar, salt, or any other ingredients, just black pepper.
If the hole in a radiator is not too large, black pepper will stop it up, temporarily, and it's better than egg-white. You can store a can of black pepper in your dash compartment better than you can an egg, and it will last longer.
Black pepper will not dissolve, deteriorate, or digest. That's why I don't eat it...plus, it burns my mouth. :-)
I say it is a temporary stop leak tool, but I've used in before and the customer drove his vehicle for over a year before he sold it.
Go to the grocery store, get one of those 2" cans, brand doesn't matter, and put it in the compartment on the dash, or the console.
Just don't use it all up at the drive-in eating places...keep it until you create a leak in your radiator.