4 liters heat up quickly. That seems a little quick for a 4.7 though. Flush it, maybe you’ve got a plug somewhere
As to the dinging: does your dash computer display show anything? My 5.9 ZJ has a bad solder joint in the dash computer and it’ll ding and try to tell me the hatch is open. Sometimes the screen goes bad and it’ll still ding an alert but not show anything. Any fluctuations in the gauges? Could be indicating a drop in oil pressure, voltage or a faulty reading of low fuel.
Sent from my pay phone in Chechnya