embroil vs throw a spanner in the works

embroil

verb
  • To implicate in confusion; to complicate; to jumble. 

  • To draw into a situation; to cause to be involved. 

throw a spanner in the works

verb
  • To introduce a problem, dilemma or obstacle, something unexpected or troublesome. 

How often have the words embroil and throw a spanner in the works occurred in a corpus of books? (source: Google Ngram Viewer )