R53 cooper s overheating...help!!

I seem to be in a big spot of bother and could really do with some help. The missus bought a '04 cooper S a couple of months ago - smashing car to drive and handy run. But about 3 weeks ago it just randomly started to over heat. Kept getting more and more frequent, happening with absolutely no warning.

So I checked a few things and noticed that the expansion bottle seemed to be leaking a slight bit of water, but a losing a lot of pressure. Did a bit of research , turns out the expansion bottle and cap give big trouble on this model. So ordered a bottle and cap from conlans and fitted. Bit of trouble bleeding it but got there eventually. That was two weeks ago. Car drove like a dream after that.

Then last when she was driving home and heard "a loud bang" - I can't confirm this yet as I haven't seen the car yet, but started to overheat again. Without warning. It seems to still draining it's expansion bottle every time and I can't find what the problem is.

- I've checked the water pump , no noises , abnormal play or leaks

- no leaks or weeps from the rad , all the piping is fine and connections fine

- old expansion bottle was leaking from the seem where the top and bottom were joined. New bottle is perfect, no leaks or hissing

- the temperature usually fly's from halfway to the red in literally a second , no warning

- the high and low fans are working when they should , seemingly a issue with them too .

If anyone has any experience with this problem can you please help this has been wrecking my head for weeks and I need it sorted

Thanks in advance,

Adam

Did you check under the oil cap? Any sign of mayonnaise? Is it the head gasket that's gone?

No mayo at all.. no smell of oil from the coolant.. car starts are drives perfect apart from this. No sign of head gasket failure from what I can see..

Just drove the car home , 10 miles and not a peep out of it. I just topped it up with water (it took 1.5 litres) with the blowers on full belt on hi temp. Left the blowers on driving back.

I'm so confused , where did the water go? It's not leaking anywhere and there's no real symptoms of head gasket failure.

I also left it running for 10 mins with no blowers on when I got home and the gauge didn't move a inch.

Had more or less the same issue with her cooper s awhile back. Turned out to be a hairline crack in the thermostat housing.

If its just water and no coolant it can use water which may explain that. Any damage to fins on the rad. Also a compression tester is 30 quid from an auto factors and would rule out a head gasket. How is the car performing? Any loss of power? Could the loud crack have been the water pump letting go? I hope not

Are these Cooper C a bad buy? I was thinking of getting one as a run around when the M6 next breaks down!