'04 Chrysler Sebring - Antifreeze leaking around a screw when hot

I have a 2004 Chrysler Sebring V6 convertible. I first noticed the expanding pool of antifreeze/coolant mix underneath the car on a hot day a week ago. I could not find the source and after refilling the reservoir to the proper level, the leak did not start again until yesterday. I drove it in about 100 degree heat and when I parked it, the antifreeze puddle was back. When I opened the hood, I could hear a boiling sound and noticed that antifreeze was boiling/bubbling up from underneath a screw that is on top and to the left of the engine. This screw is on some piece of equipment that connects the antifreeze reservoir hose with hoses to the radiator and back of the engine. This is where I am losing my antifreeze. I tried tightening the screw, but I really can’t see what it is there for, so I don’t want to remove anything. Any suggestions on how to fix this thing (or what the screw is holding there?) Thanks!

OK, took another look now that things are cooled down. The coolant is leaking between an upper and lower plastic piece screwed down by 4 screws. I believe the heat sensor is what is sticking out of the top of it. In May, I had to have the upper plenum gasket replaced along with the spark plugs. No idea what a plenum gasket is…

Using a bright light, look VERY closely at the area of the leak. Are you SURE the plastic part you mentioned is not cracked?? It almost sounds like the thermostat housing or cover but those are seldom made of plastic, even on Chryslers.

Chrysler’s Got Plastic Ones With A Little Brass Insert That The Bleeder Screw Screws Into.

I’ve even seen them leak around the insert which is a permanent part of the housing.

CSA