Hello,
A week back, my 2008 standard mini cooper’s, lower radiator hose got loose and was touching the ground (supporting clamps got loose). This developed a leak as it was touching the ground as I was driving the car while this happened. All of the cars coolant ran out, a local service mechanic replaced a new lower radiator hose and also completed the process with off the shelf 50-50 antifreeze coolant. ($200 in total) (Always serviced car at the dealership/Mini Mechanics. However I live in the country and could not get to a dealership which is 75 miles away).
Few days post repair things were fine and now the coolant has started to leak again. I believe the coolant is pushing itself out from the coolant cans “cap”. Low coolant alarm came one day and I topped off the coolant. However most of the coolant got drained from the system. I even have a video with coolant pushing itself inwards in the coolant can. The earlier mechanic mentioned, this could be an air pocket.
Another mechanic will look into it tomorrow. As a symptom of this issue, the heater is blowing cold air.
My question, is how serious is this issue ?I am driving the car in current conditions for 10 miles today work and back home. How major a repair am I looking at ?

 

Cooper or Cooper S? It could be a bad seal on the coolant tank cap. It sort of looks like the smoke is coming from the seam area of the tank. If it is indeed the tank, it's relatively inexpensive to replace.

2008 Mini Cooper S Hatchback - Radiators - Page 3

 

I know this is an old post but I have the same issues with my 2007. Bad news is the engine is done. Exhaust is leaking (warped head or warped engine bock. The exhaust is leaking into the cooling system and causes the coolant to boil and push out the overflow tank. Well at least that is the cause of mine doing the same.

I thought it was my tank as well and replaced it but still the same issue. The tank is about $100 so def worth a shot