I got home to find a trail of coolant down the driveway and puddles forming under the car (1991 Toyota MR2 - 5SFE). Concerned that I blew a hose, I checked them all. Nothing. Finally decided to see if I had anything left in the overflow to see how much I'd lost on the drive home. It was overflowing!
Here's the weird things: Temperature gauge was perfectly normal the entire drive home, not high, not low. The coolant in the overflow was cold (room temperature), I expected it to be hot. No smell of coolant burning/cooking off either.
Once the engine cools down I plan on checking the oil cap for residue and the dipstick for level/residue, but if it was a headgasket the coolant should be hot. Ditto for thermostat & fans. Water pump failure and the gauge should have either gone high or low, not stayed normal.
I'm baffled. No prior indication of any problems. Seemed to happen out of the blue. Ideas?