First off, you are welcome! I am glad it is being put to good use.

As for the coolant loss, lets reverse this.

So how are you seeing coolant on the floor and knowing it is from the back of the motor?

When you took the top end apart, did you securely fasten the bolts to the water accumulator?

What about the O-rings? Did you lubricate them before putting them in? Did they go into the grooves and seat properly?

I am assuming using the Black RTV, you reused your valley pan. Scraped the gasket off, reapplied the thin bead, let it set for an hour and then se seated it correct? Did the gasket, after you torqued it spill out the sides a bit.. did it squeeze out evenly?

Get back to us.

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2011 E70 50i M Sport