Some guessed correctly. It was a clamp.
When I stopped at the store a puddle of coolant formed on the ground under the passenger’s side end of the radiator. I had no smells as symptoms because coolant did not steam or land on any hot engine parts.
At the golf course, after the car cooled for about 5 hours there was more coolant under the radiator, but surprisingly the leaking had stopped when the car cooled.
I noticed the recovery reservoir was nearly empty so I took off the radiator cap and the radiator was full to the top of the neck. I carry “make-up” fluids (oil & Dex-Cool coolant) in the trunk and although it wouldn’t necessarily help me I added coolant to the reservoir so I’d feel more normal .
I was sure that the radiator was shot and decided to drive home (I have a temperature gauge and a “low coolant” message in the driver information center.) where I could install a radiator myself. I checked and Rock Auto could get one to my house for $107.
When the car was cold I snaked my hand (tight fit) to the bottom of where the lower radiator hose attaches to the radiator (above the leak). It was wet underneath, but dry above! Could it be just a hose that went bad? I bought a hose and started to remove the old one. When I squeezed the factory installed radiator clamp to remove it the clamp offered no resistance and fell apart! The clamp consist of 2 bands and 1 band was very rusty like it had been broken for a long time (see pictures).
This picture shows that the clamp was a little hard to access. The golf tee is pointing to my all stainless replacement clamp.
Have you ever heard of somebody driving down the street and had a catastrophic hose clamp failure? I have not experienced this. I tried to figure what caused it. Believe it or not I don’t think it was rust, but I’m not impressed with the quality of the steel in the clamp. And, “yes” I checked the motor mounts to be sure the engine didn’t pull on the hose. Could one of the bands on that clamp been broken when originally installed at the factory?