Let's diagnose an oil leak
 

Newly rebuilt short block installed. Included new timing chain cover, oil pump, new oil pan gasket.

I have a 2-3" diameter drip on the floor overnight. Once it's dried up it doesn't drip again until car is run.

Drip falls, from right side rear oil pan bolt.
https://cimg2.ibsrv.net/gimg/www.nor...1d88cc5eaa.jpg
Back of block above pan is dry. Timing chain cover is dry.

Bottom corner of block is wet
https://cimg1.ibsrv.net/gimg/www.nor...d579d88ac6.jpg
Gap between pan and timing chain cover appears to have oil in it at least back to belt.
https://cimg4.ibsrv.net/gimg/www.nor...71e9f8e8b9.jpg

I'm guessing either pan gasket (pretty hard to screw up), timing chain cover gasket (new with new cover) or one of the oil pump seals (also new, but I didn't specifically check them).
https://cimg2.ibsrv.net/gimg/www.nor...fd8e27c408.jpg

Where would you start?

I'd prefer to do the pan gasket since I don't have a puller at the house to pull the crank dampener, but I think it's more likely something to do with the timing chain cover/oil pump assembly.

Any wisdom to share?

Loose oil cooler torx bolts. Give them another snugging up.

I would have expected anything to do with the cooler or filter housing would have left tracks down the block? The whole back of the block is dry. The only oil is on the top edge of the pan on the back and passenger side.

Sounds like the pan wasn't torqued properly and/or in the right sequence.

I hope that's the answer, as that will be the easiest to fix!

Does anyone know how high the oil level is in the pan when engine is not running? Car had been sitting for over 24 hour last night when I posted and I wiped everything down.

I had a 1"puddle on the floor this morning-more than 36 hour since engine last ran. I woukd think if it was a pan gasket I wouldn't be dripping again because I assume the oil level isn't above the pan at rest?
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have you tried uv dye? that's where i like to start. it'll work great, too, with your clean engine

Quest Multiple Use Leak Detector UV Dye Oil ATF PS Fuel 1oz

Get this @ Autozone or Oreilly autoparts , this works great for pinpointing leaks …

I used the UV dye on my N12 R56 cooper engine; I easily found all my oil leaks.

Realized I never updated this. I ended up pulling the timing chain cover. Oil pump outlet seal had gotten tweaked when I installed the cover. FIxed that, put it back together, and it still leaked.

Pulled the cover, ordered new inlet and outlet seals and a new cover gasket. Scraped everything and cleaned the surfaces, added the RTV at the joints on the block face (did this at initial assembly as well). Everything sealed up and car is running great.