hole in right bank valve cover? on 2002 Ford Explorer

This morning was a cold start.The engine rpm's went high for a brief second.Started smelling oil and found a hole in the rocker cover.Looks like a timing chain in that location.What do you think caused the hole in the right bank rocker cover?

Asked by for the 2002 Ford Explorer
Is it clean hole or do you mean the cover is cracked/broken?
If it looks like the hole is meant to be there, look for a dangling vacuum hose or PCV valve. Is there a grommet on the hole still? Were there any extra noises when it was running?
If you lost a tensioner, your check engine light would most likely be on with some kind of cam sensor code. Something may have come loose but it's hard to say without pulling it apart. A used cover will work but it is a good idea to do a thorough inspection when you pull it apart. A bolt from one of the guides may have backed out and you may have correct time. Pull the covers and do a check for anything missing and check tension or slack in the chain.
Something you can try is change your oil, and look for any debris or metal pieces when it drains. Putting a screen under the drain should catch any large pieces. hope this helps
1 more answer , 1 more comment
Are you missing your oil filler cap?
no, the filler cap is comment #2- not a clean hole,irregular shape about the size of a quarter. Yes there is a noise coming from the front side of the engine. The noise is a slight ticking,not hammering or a knock. I'm thinking some sort of timing chain tensioner came loose to create the hole in the rocker cover. The engine runs fine. I'm wondering if I get a used cover I might be ok