Why coolant coming out of overflow tube from expansion tank?

What is your question?

Got this car from original owner in 2013. It had 50,000 original miles in the first 21 years. In last 2 years I put 24,000 on it. I noticed some coolant was coming out of overflow tube on expansion tank(and coolant was boiling/bubbling in expansion tank.) Car was also making a "marbles rolling around in coffee can" noise at this time and it hadn't been before. I took it to be a failing water pump. I replaced, water pump, thermostat, radiator cap, all coolant, flushed coolant system. Electric fan seems to work, at least when a/c is on. No issue for three weeks. Today car is expelling coolant again from expansion tank overflow hose. And "coffee can with marbles noise" is still there-leading me to think timing chain/guides are beginning to fail. So, Any guesses on coolant issue? How about coffee full of marbles noise issue? Thanks!