Hi! I am in the middle of trying to figure out what has caused the oil and the engine coolant to mix of my 2009 cooper. After removing the cylinder head cover I found the timing chain guide broke off and a 1 inch cap was wedged down in the timing chain compartment where that orange plastic guide is in the pictures below. Any idea what would cause the guide to break, and what this cap is?

 

Sorry to say they main reason for oil and coolant to mix is a blown head,or a Crack in the block,can't see what the part is but would look at a good engine rebuild or a replacement engine from a insurance loss car.good luck keep us posted