First post, searched around the threads and not sure anyone has had this exact problem with a CM yet. Last week on my 2012 CMS fwd w/ 5200 miles noticed that coolant was below the minimum. Added Zerex G-05 up to the max line and took the car on a 250 mile road trip over the 4th. Got back last weekend and coolant was about half-way between the min and max marks (cold). I've also been experiencing an intermittent rough idle at cold start, as well as on very hot days with the A/C at max and idling at stop lights.

Took it into passport Mini in Alexandria today, and awaiting the results. I've yet to have the coolant temperature sensor replaced, but I'm not sure it actually applied to my build or not (dealer didn't seem to know either). They're also going to take a look at a bunch of rattles/squeaks that have developed since about 4,000 miles.

 

Got my car back from the dealer. SA says that they could not duplicate the rough idle. The source of the coolant "leak" was that the system was in fact never bled properly and had air bubbles. So whenever topping off the coolant, you're never going to get it completely full. They also did end up replacing the coolant temp sensor.

They also claimed they couldn't duplicate the various NVH problems--plugged the two rear seatbelts into their holders and said they were the source of the rattling against the plastic housing on the side.

I'm due for service in about 800 miles, so we shall see how the rattling, and coolant level hold up.

 

Glad they took care of the radiator. My coolant temp sensor needed to be replaced too.

So what's going on with your idle? Is it just a noise or are the RPMs bouncing up and down too? Power loss off the line? Could be a symptom of clogged intake valves, but 5000 miles seems way early to need walnut blasting.

 

Had this problem with my all4. Rough idle and tendency to sputter when engine was cold. Cold temps <45F exacerbated the problem. Brought it to dealers attention almost every time it was in and only got the run around.

 

Hey So what was happening to your Rad Fluid? mine is going somewhere...... I don't know where... I am at 27k never had anything replaced or done to my 2012CM.

 

if yours has the plastic water pump and not the updated 'metal' ones, then it's probable that the coolant slowly leaks and the dealer will not even detect it with a pressure test. my r56 had this issue - coolant slowly disappears - until the plastic water pump finally leaked drops on my garage floor. dealer replaced it with updated metal water pump and no more disappearing coolant.

 

Thanks I will take note of that.... I have no idea what I have.... My overflow is plastic (I doubt that is what you are talking about)

 

my main water pump (located on passenger side) was replaced with the metal version. i read MINI started using the metal ones somewhere in 2012...