There were some posts on flying in heavy rain some time ago and whether or not this might affect the engine performance or cause stoppage.

Whilst browsing through an old POH for the C 172 I noted in the normal ops section that "the use of carburettor heat in heavy rain is recommended both to prevent build of of carby ice and to avoid engine stoppage"

It seems Lycoming (or Cessna) consider engine stoppage due to rain a strong possibility

Gerard