850t coolant temps

Post by **rguzz** » 19 Sep 2021, 14:51

Coolant temp all day long in town is between 187-205, you can idle for a long time with very little variation. Heater core is new Behr in maybe 6 months. But there is considerable and almost immediate temp increase under load driving in the hills. After just a minute of uphill driving temps get to 220-225, max out there. They drop immediately when you begin to coast downhill. I have no memory of this ever in the past, seeing 30F degree fluctuations brought on by load, then corrected almost immediately when coasting, or running downhill. Radiator is Nissens, maybe 12 years old. Is it plugged up? Should I replace it, just because of it's age and behavior? Thermostat is fine I believe, and newish, operates as it should warming up, etc. But the slightest sustained incline will quickly increase coolant temps, which can drop equally quickly. Replace radiator or not?

Post by **abscate** » 19 Sep 2021, 19:21

Totally normal. Your engine will make 10-25x more heat working up a hill than Idling. Coolant temperatures can run up to 235F

Post by **rguzz** » 19 Sep 2021, 20:20

Yes. Just can't quite understand why, over many years now, I've never noticed this degree of fluctuation.

Post by **abscate** » 20 Sep 2021, 06:47

Somewhere buried in the forum is my photos of being stuck at the US CAN border and watching my coolant temps cycle between 87 and 105C at idle as the fans cycled

105C roughly 221F for reference