1995 Acura Integra coolant leak, clanging sound

My car runs hot when I'm driving slower or idling. It has all new hoses, I got a new radiator in 2005, it's current on water pump and timing belt, and I got a new thermostat about a month ago.

I have to frequenly add coolant to the radiator before extended drives of more than an hour or two. Today while driving some curvy, mountain roads, the temperature gauge went very fast to about 85% hot. I put the car in neutral and pressed the gas enough to bring the temperature back down.

When the car cooled, I added about 7 oz of coolant to the radiator. And about an hour later, I heard a new sound - a "clanging" sound like something was about to fall off from the bottom of my car.

This was not the case, as I looked and didn't see anything. As of the time I'm typing this, my car is still hot so I don't know how much coolant is left. It didn't run hot, just made a clanging noise.

I have my car scheduled for a diagnostics test for $120 at the Acura dealership. I was hoping to have a quick fix instead of getting into another car payment. But it sounds like my car is on its last legs.

Thank you for any diagnosis you can give me.

Wendy