Originally Posted by BroncoHound
I'm in the same boat. Coolant was a little low when I got the car back from a local guy walnut blasting and replacing the oil filter gasket. I added some Preston 50/50 that I've had on the shelf for a while and, about 100 miles later while cruising on the highway at 65mph, yellow to red to park on the shoulder. I let it cool off for about 5 minutes, started the car back up and all was good, no more temperature alarms. Drove it the 4 miles home and parked it. No leaks, no evidence of coolant splashing against anything I can see. I haven't driven the car or checked for codes since (been out of town for work) and was literally JUST about to order a new water pump and thermostat when you posted about a fluid difference.
Just speculation, but I wonder if a fluid flush and fill, all with the same type of fluid, would solve yours and my particular issues.
And, a little rant about how piss poor a design this is. A part that can cause catastrophic failure of the engine if not immediately diagnosed has no way to diagnose failure except with replacement and crossing ones fingers. Absolutely shameful.
So my car consistently warms up after about 4 miles or 10 mins running, then fans kicks on high, then yellow to red - every time. Tray was taken out, no leaks, splashes evident - under car or from the top. So the only thing I have are the codes, which state those two conditions, water pump on/off due to fluid difference. Wonder if it's a sensor now or again if the water pump is to blame.