So, over the last few months, the cooling fan will turn on a minute or two after starting the car and stay on the entire time and finally turn off a few minutes after turning the car off.

Last week, I started having issues with my R53 overheating and had to keep the heat on full blast to keep the temp gauge at the half way point for my drive home and I haven't driven it since.

A few things to note:
- I am losing coolant and have had to fill the expansion tank a few times
- I know that my expansion tank is leaking and I will be replacing that this weekend
- the problem still remains if the expansion tank is properly filled
- there is no coolant dripping to the ground

Other than the expansion tank, should I look at making any other repairs?

TIA

 

Get your tank fixed. The R53 cooling system requires pressure to work properly. I am OCD so if my car was overheating I would refresh the whole cooling system. Check the fan resistor, known problem for the mini. Get a scanguage or similar and make sure low and high speed kick on at the right temps.

 

Yeah, I am planning on doing a full flush of the system so hopefully that will solve everything.

 

Yes, once tank replaced, check the fan resistor for sure (wiring on mine was shot), it's a very cheap fix, maybe $20 for new resistor.
Also check thermostat, another very easy and cheap fix, the plunger on mine would get stuck at random points of time and would then cause overheating. Sourced one from my LPS and installed 20 mins later.

Other than that, as long as no leaks anywhere-- the tank, radiator, hoses, thermostat housing, etc.-- send a quick prayer up and hopefully it should be resolved.

 

Beware of false diagnoses.

If your coolant system overheats like in your case the expansion tank is design to do its job, not to explode into pieces by releasing the overpressured and thus overheated (super heated if you like to call it), and the release at the cap will always lead the untrained eyes that the tank is leaking. A case in point. Driving my Mini hard on track on hot days will invariably leave coolant residue on the tank, and is totally normal even if I didn't overfilled.

Your symptoms is a failing or outright failed thermostat. The water pump is likely fine if you are getting heat by turning on the fan. That loop bypasses the thermostat.

 

Very good explanation of the system and symptoms.

 

Ok, so after replacing the expansion tank and doing a full coolant flush, the overheating continues.

i have a new thermostat and housing on order, so we will see if that solves it.