i have a 2008 mini r56 base model that is over heating. there are no visible signs of coolant leaking from anywhere. nor does the oil show signs of contamination from coolant. i have thus far installed a new thermostat and sensor and a new water pump. which leads me to a head gasket or block crack. but just came across what i thought to be an unrelated issue but have been told it could be related.

i was installing a new breather hose and to do so had to remove the intake manifold while doing so i found that the 6th and lower bolt used to mount manifold was missing. i loosened the top 5 bolts and the manifold came free. 

could that missing bolt be the cause of my overheating???

i should also mention there is intermittent white plumes of smoke from tail pipe and no determinable evidence of coolant at plugs

thanks