Technical Is It Nice To Be Seeing Green?

Dear H.A.M.B.-ers
Started doing some maintenance on my 1940 Ford Coupe. While I was crawling around underneath checking the front end I noticed my radiator was showing some greenish color. Almost the same color as old copper flashing. The radiator was not wet and no antifreeze residue was on the floor. It has shown no signs of using antifreeze unless it is over filled then it pukes out what it does not like. The level is about an 1-1 1/2 below the filler neck. The car runs at just over 185 degrees most of the time unless the a/c is running and then it will climb to 195 in traffic, but drops to 190ish during cruise. .I had the radiator rebuilt in 2011 as it had a crack in the upper tank at the bottom where it fits to the radiator core. The shop rodded it out, re-soldered the tank, and pressure tested it. I think it is an American Radiator Co. brand? not sure as it was painted body color. It is not aluminum so i am guessing copper/brass( sure looks like brass in side the tank during fills) I choose to rebuild it as I know it fit into a very tight space. Just one of the issues with a bought rod I guess. Here are a couple of pictures.
Any explanation or suggested course of action would be greatly apprecaited as always, this knowledge base is incalculable.
Thx
MrPhat40

 

Same color as the Statue Of Liberty, and she's made of copper!
Hose it off, let it dry over night, blow it off with low pressure air, give it a light coat of cheap black spray paint(the cheaper the better) as you don't want a high film build up.
KK

 

Patina is IN these days, but Will cause problems down the line. Chemicals misbehaving.

 

Could be a area where acid residual opened the surface to the elements and did not get properly rinsed/painted

 

Thank you all.
It looks like something I will need to keep an eye on.