Straight plastic connector between two heater hose sections failed catastrophically shortly after turning off ignition. Noticed some temp gauge fluctuations while driving, but nothing in the overheat range. Seemed to take a long time to come up to temp (thermostat?). Wondering if failure was likely just due to old plastic part, or could there be a more serious root cause. Didn't steam very long so I couldn't locate the problem until I tried filling radiator after cool down. It was dark by then, so I couldn't feel or see what water level was in radiator. No coolant leak problems previously except for bottom radiator hose and water pump failures. Both have been replaced.

Thanks in advance for any helpful advice.

 

If the plastic connector was original, it more than likely was just old age and time for it to fail. The flowing coolant can be corrosive and just eat the plastic away.