Originally Posted by JimBlake
That tool helps you look for leaks. It doesn't test whether the inside is full of crud; which would block the heat transfer but maybe not cause a leak.
True, true..., but the man said he replaced his coolant out and put in a new t-stat. I imagine he flushed out the radiator in the process.
I guess the question should be did you find particles or "crud" in your coolant when you drained the radiator?