I turned off every option in System Settings but I can't add any drive to the exclusion list. I'll always get an empty window.
If disabled in Terminal this way I still can search in Finder:
	
	
	
		Code:
	
	
		sudo mdutil -d /Volumes/"Macintosh HD"
	 
 
It says "Indexing and searching disabled."
You can also use 
	
	
For all Volumes at once. For TimeMachine drives only searching can be disabled, not indexing.
Before I turned it completely off with:
	
	
	
		Code:
	
	
		sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
	 
 
What is only working with SIP disabled anyway.
Then I got a message in Terminal that the Spotlight server is turned off when I wanted to use mdutil and searching in Finder didn't work.