Hi guys,

Please help me out.

My Quest suddenly overheated in one day. And then the thermostat got changed. But now, I got a puzzle to figure out. The scenario has lasted for a few days as follow:- I parked my quest outdoors. it is about -5C ~ -10C in the night- in the morning, after 5 minutes the quest got overheating- keeps driving slowing or let engine running in idle, or shut down/restart the engine, the temperature keeps increasing- when it is overheating, the upper hose is warm, but not hot, and the lower hose is cold. the radiator is cold. the coolant is enough.- after a few minutes, the temperature will suddenly drop to normal.- in the rest of the day, the car won't get overheating until the next morning.- after the temperature is back to normal, the lower hose is warm, the radiator is warm, and the fan will be running on/off.

please help!

don't really understand what you're saying...

how did it overheat all of a sudden?

when you replace the T-stat, did you purge the cooling system of air bubbles?

there's a wacky way to do that when you go look into the service manual of your vehicle (maintenance section) http://www.nicoclub.com/FSM/quest

so what was it...

the new/ replacement thermostat was stuck closed?