My daughter has a 2011 Ford Ka Mk2.  I noticed lots of oil patches under the car where it was parked and checking under the car can the bottom of the engine is wet with oil.  Looking down from the top of the engine I can see a crack which looks like it is the gearbox.  See attached picture.  Is this the gearbox?

I also read the ODB2 codes and it shows a misfire on cylinder 2 and 3.  If that is the gearbox then how could that cause a misfire?

The part you refer to is the bellhousing . The bell housing has the clutch inside. On some cars the bell housing is part of the same lump of metal as the gearbox but on this one it looks like the bell housing is a separate casting which bolts onto the gearbox.

I can’t see how that crack can relate to oil leak or misfire. Fault codes can remain in the memory even if not occurred for a while. Clear the codes and see if the code comes back. 

Thanks @isetta.  I guess the oil is from the gearbox and seaping out of the crack.  It seems much cleaner than what I see on the dipstick. 

I looked up one pictures of the bellhousing and it looks like there should be a cover over that gap to the left of the crack.  I wonder if something has got in there and that is what caused the crack.

I will clear the codes as you suggested and see if they appear again.  The engine itself sounds like it is running normal.

 

I am wondering where the lower end of crack is. I would be a bit worried that something is going to break off and leave you stranded. Put your finger on the top end of the crack and get someone to push clutch pedal up and down fully. I am thinking that every push on the clutch pedal is stressing that crack.  But it’s a lot of work to get it out and replace it.  Just unlucky I guess that it happened to you. That piece of metal with the crack should not have any oil in it.  If there is oil in it then it is leaking from somewhere else eg crankshaft rear seal behind flywheel or gearbox input shaft seal

Ps, be careful when your finger is on the crack as that rusty lever will move towards your finger when clutch pedal operated. So don’t get your finger squashed/ trapped