Will it work with a soaking wet radiator?
I would of thought you would need to drain coolant and get it all dry before applying? If not then I really should get some of that stuff!
The answer is yes if you can stop it dribbling out. But ideally you need to key the damaged area if the paint is loose. It's only as good as the surface it's being stuck to obviously. in this case you need to make sure a lump of the putty doesn't drop into the radiator and start circulating round. Again simple really.
https://youtu.be/6Ko7r7pveBQ
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