Originally Posted by Savannah Buzz

Nope, it is supposed to come on at 212F even if AC is off, turns off at like 202F. Also can come on if underhood temp is too high 10 seconds after key off.

Originally Posted by Savannah Buzz

That is the throttle body heater plate, it starts to leak, you don't notice, coolant is low, bad things happen. The purpose of the plate is to keep the throttle valve from icing up and sticking open, a runaway Rover on an icy road is revolting.

You have taken on all the cooling system, but many items may be OK now. The water pump usually wobbles and leaks out front when bad. The radiator, when clogged, shows a temperature difference across the fins, from to to bottom, of 10F or greater. That is because the lower rows clog up first. The coolant cap can start venting at lower PSI, secretly while driving, which can be detected by a paper towel zip tied around the overflow tube from the coolant jug. Fan clutch test is spin and release. Should feel like peanut butter inside, not coast more that a partial revolution. Do both cold and hot. If it freewheels, the silicone fluid inside is gone, and you will have poor cooling at idle or slow traffic. Electric fan is opposite, drag on it indicates bearing siezing up, frequently blows fuse, and people don't notice it until overheating.

The thermostat is a good thing to change because a lower temp one will cool engine about 10F.

The plastic rad has a screw boss in the top of the tank. Too much force, wrong size screw, and small crack is formed that will leak.

The bleeder valve is prone to break, BMW dealers sell a brass replacement. Or people home brew the whole T. When bleeding air, don't stop at first few bubbles, ther will be more. Air in coolant makes a sound like water rushing thru pipes nder the dash. Could be air, could be exhaust gas in coolant from head gaskets.

The dash heat gauge is built to show 50% from 130 -240F, so watching it is not a good indicator of making incremental improvements on cooling. That is where the Ultra Gauge comes in.