I recently bought my 2009 Mini Cooper hatchback. It overheated due to coolant not being bled properly, we got that fixed, immediately changed the oil and filter. After overheating it had a knocking noise, thought it was the timing chain, removed the cover and discovered chain is fine, but two rocker arms on the exhaust side of the cam are completely loose, will come off, this is what caused the knocking. The valve springs below these seem to be a bit shorter. Can anyone direct me further?

 

It might not be related to the overheat, but it feels like the valves are bent! do a compression test and DO NOT drive the car because these rockers might actually come off and cause some damage.