I have a small coolant leak at the top accessory side of the block/manifold after cool down. One possibility I thought of was the freeze plug at the top of the block below the manifold, but I can't see down there to confirm it, though. Sometimes these leak with temp changes. It won't leak under a pressure test or a normal operation temp. with the engine running. No leak from the water pump, hoses, cross pipe, head gasket or hex plug that I could see. I may try a UV tracer dye. Any other ideas?

 

You seem to have come up with the best solution. Over time keep an eye on the coolant level. That will at will tell you how drastic it is.

 

only thing i can think of is hoist the car up, spray the area the coolant leaks from with brake cleaner so it dries out quickly, and sit there for a bit with a light and watch where its dripping from

any rust on your car? generally from what ive seen its rust over time that makes frost plugs start to leak

 

I would just trace the trail back to the area it came from then narrow it down there.